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SCIENCE • HISTORY • NATURE • FOR THE CURIOUS MIND

HOW DO WE

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R.N.I.MAHENG/2010/35422

www.knowledgemagazine.in Volume 4 Issue 1 December 2013 `100

SCIENCE • HISTORY • NATURE • FOR THE CURIOUS MIND

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On the coverhe nature of the Sun, and why it was glowing hot, remained unquestioned until the middle of

the 19th Century, when scientists started wondering how heat related to the power of steam engines. The French engineers Nicolas Léonard Sadi Carnot and Émile Clapeyron studied steam engines and were the first to create a new branch of physics: thermodynamics.

In the 1840s, the British scientist James Prescott Joule performed his famous experiments that supported Hermann von Helmholtz’s idea that mechanical motion, heat, and radiation are different manifestations of what he called ‘force’, which now corresponds to the modern concept of energy. With it came the realisation that any source of power, is finite, and scientists started to wonder what was the seemingly infinite source that powered the Sun.

Solar powerHelmholtz agreed with the views of philosopher Immanuel Kant and mathematician/astronomer Pierre-Simon Laplace that the Sun was formed by the

physicists Ernest Rutherford and Frederick Soddy soon identified it as radioactivity: atoms decaying by splitting up into smaller atoms. The mass of the newly formed atoms is less than that of the original atoms splitting up, and this tiny difference in mass is transformed into energy according to Einstein’s formula for the equivalency of mass and energy: E=mc2. Therefore, it was not surprising that Rutherford thought that nuclear fission, that produces heat inside the Earth and in nuclear reactors, could also heat up the Sun.

In the meantime, to astronomers, the Sun appeared as a huge ball of hydrogen with small amounts of elements, such as helium, oxygen and carbon. There was insufficient uranium or other heavy elements present in the Sun to enable nuclear fission reactions.

If atomic nuclei can split into smaller nuclei, why would smaller nuclei not be able to ‘fuse’ into bigger ones?

This was what the American chemist William Draper Harkins asked himself, and in 1915, proposed that the fusion of hydrogen atoms, forming helium atoms,

contraction of a huge gas cloud – a theory viewed as correct today. He argued in 1854 that the compression of the gas cloud caused the Sun to heat up, an idea defended by the British Physicist William Thomson (Lord Kelvin) until the 1890s.

Kelvin figured out that the Sun could not be more than 40 million years old, and he clashed with the geologists and biologists of the time. For example, Charles Darwin’s views on evolution required the Earth to be much older. By the end of the 19th Century, geologists had sufficient evidence that the Earth had to be more than a billion years old.

The first glimpse of a possible solution came American geologist Thomas Chrowder Chamberlin. He suggested in 1899 that “unrecognised sources of heat” may exist inside the Sun, energies of an “atomic or ultra-atomic nature”. Kelvin rejected this idea, but the discovery in 1903 of a weird property of the chemical element radium, recently isolated by the French physicists Marie and Pierre Curie, made Chamberlin’s idea acceptable.

The material had a mysterious heat source that kept it hot. The British

> IN A NUTSHELLFind out how scientists made the

intellectual journey from believing that the Sun was powered by an endless

meteor bombardment, to discovering a nuclear reaction that stretched our

understanding of physics to its limits.

The Sun provides Earth with abundant energy, produced by a nuclear reaction that took physicists decades to figure out

WHAT POWERSTHE SUN

Until the 19th Century, no one had any idea how the Sun produced energy. Understanding the atomic nucleus and the chameleon-like nature of an elusive

particle finally resolved the mystery

BY ALEXANDER HELLEMANS

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From the first investigations involving cooling spheres of iron over 200 years ago, to exact measurements of isotopes in meteorites, the quest to fathom the age of the Earth has been a difficult path for generations of scientists. With a cast of characters as diverse as its many types of experiment, find out about geology’s finest hour.

THE

AGE OF THE EARTH

BY DR CHERRY LEWIS

oday we know that the Earth is 4.54 billion years old, plus or minus one per cent. It’s a number

that has changed little since it was first determined 57 years ago, back in 1956 – only the error has got smaller. But how can we be so certain that it is accurate and why did it take so long to find it? To answer those questions we must turn the clock back three centuries.

Archbishop James Ussher was just one of many scholars in the 17th Century attempting to establish the exact day on which God had created the Earth. Starting with Adam, Ussher developed a chronology for all the significant people in the Bible. He then added up their ages to determine that heaven and Earth were created on 23 October 4,004BC, which was a Saturday. This date would have remained as unknown as all the others had it not been for an enterprising bookseller called Thomas Guy who recognised a demand for cheap, mass-produced Bibles. In 1675 Guy began printing a version that included Ussher’s chronology in the margins.

different places, ages calculated using these rates produced a broad range – from 3 to 2,400 Ma.

The second hour-glass method attempted to measure the rate at which salt accumulated in the sea. Rivers hold dissolved salts in solution, derived from decomposition of the rocks over which they pass. Assuming that the sea had originally been pure water, they thought it should be possible to measure the time it had taken to accumulate present levels of salt. But this method was fraught with difficulties and also led to a wide range of ages.

Then in 1862, Lord Kelvin, a renowned physicist argued that the Earth had originally been molten and considered it ‘obvious’ that if the temperature at which rocks melted and the rate at which they had cooled down was known, then it should be possible to calculate the time at which the Earth’s crust had consolidated. Given these unknowns, Kelvin gave his estimate to between 20 and 40 Ma. There was uproar from the geologists.

The decade that straddled the turn

Spheres of timeAs knowledge about geology gradually accumulated, geologists began to realise that a few thousand years was just not long enough. In particular, a French Count, George-Louis Leclerc de Buffon, believed that the Earth and the planets had all originated simultaneously from a plume of intensely hot material torn from the Sun. Over a period of 11 years, Buffon conducted extensive experiments with spheres of iron and rock of varying sizes, and published his results in 1775, giving the age of the Earth as 74,832 years since its formation to its current temperature. Over the following century, evidence for the aeons of time needed for geological processes began to emerge from studying the rates at which they could be seen to be operating, and by the middle of the 19th Century two of these ‘hour-glass’ methods prevailed. The first attempted to estimate both the total thickness of rocks in the world and the rate at which sediments were deposited, which gave the time taken to deposit all the rocks. But because deposition rates are different in

It’s taken three centuries for scientists to pin down the age of our home planet, a complex task with a

cast of characters as diverse as its many experiments

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From controversial beginnings to irrefutable evidence, it’s taken over 200 years to reveal Earth’s Ice Ages

BY JOHN GRIBBIN

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HOW DO WE KNOW?

or hundreds of years, European people were aware of large lumps of rock, some as big as a house,

lying around in places where they didn’t belong, far from the strata where such material originated. They became known as erratic boulders, shortened to ‘erratics’, and until late in the 18th Century the accepted story was that they had been dumped by the great Biblical Flood.

But in 1787 a Swiss preacher, Bernard Kuhn, suggested that these boulders had been carried to their present locations by ice, not by water. In the 1790s the Scottish pioneer of geology, James Hutton, reached the same conclusion after a visit to the Jura Mountains of France and Switzerland. But the idea languished until it was taken up and vigorously promoted by another Swiss, Louis Agassiz, who was born in 1807.

Agassiz picked up the Ice Age idea from a geologist, Jean de Charpentier, who gave a talk on the topic in Lucerne at the 1834 meeting of the Swiss Society of Natural Sciences. He reported how heaps of rocky debris, known as moraines, are left behind by retreating glaciers, and speculated that the Swiss glaciers had once been joined

across the surface of that huge ocean of ice.’

Such language attracted attention, but in scientific terms a much more important event also occurred in 1840, when Agassiz presented his ideas to a meeting of the British Association for the Advancement of Science, held in Glasgow in September. The great geologist Charles Lyell, who was a big influence on Charles Darwin, was in the audience, and like many who heard the Ice Age theory for the first time, was unconvinced. But as a good scientist, soon after the meeting he headed into the Highlands to look for evidence in the form of ‘terminal moraines’ left behind by long-melted glaciers, and found them.

Before the year was out, the Ice Age theory had been presented to the Geological Society in London, endorsed by Lyell, and established as fact. But this raised more questions. When had the Ice Age occurred? And why?

The seeds of the modern theory of Ice Ages (note the plural) were sown in a book published in 1842. The author was Joseph Adhémar, a mathematician who worked in Paris, and his book was called

in a single ice sheet extending across the mountains and perhaps reaching into the nearby lowlands of Europe.

Controversial findingsBy the time the next annual meeting of the Society came around, at Neuchâtel on 24 July 1837, Agassiz was its president. The audience settled into their seats expecting a dull presidential address on fossil fishes, and were astonished when he let rip with an impassioned lecture on the Ice Age, in which that very term was introduced (in German, as ‘Eiszeit’).

In 1840, Agassiz presented the evidence in a book, Étude Sur Les Glaciers, written in language that could not be ignored: ‘Europe, previously covered with tropical vegetation and inhabited by herds of great elephants, enormous hippopotami, and gigantic carnivora became suddenly buried under a vast expanse of ice covering plains, lakes, seas and plateaus alike. The silence of death followed… springs dried up, streams ceased to flow, and sunrays rising over that frozen shore… were met only by the whistling of northern winds and the rumbling of the crevasses as they opened

> IN A NUTSHELLFrom solving the mystery of giant boulders

left scattered across Europe, to intricate calculations describing the motion of the Earth around the Sun, it’s taken over 200

years for scientists to discover when and why Earth has periodic frozen epochs.

Erratic boulders, left by great glaciers of the Ice

Age on Bealach na Gaoithe near Torridon, Scotland

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How do we know?

ncient Greek mathematician Euclid believed that sight occurs because the eye emits

light. Hero of Alexandria pronounced that light must travel at infinite speed as distant stars appear at the instant one’s eyes open. And in the 11th Century, the Basran mathematician Alhazen wrote his Book Of Optics, where he argued that light moves from object to eye, with a finite speed that varies depending on the medium through which it passes. Ideas continued to flow. In the 13th Century, Roger Bacon used the ideas of Alhazen to support the idea that light travels at a very high speed, faster than sound but finite.

As late as the 17th Century, luminaries such as Kepler and Descartes insisted that light travels infinitely fast. In 1629, the Dutch philosopher Isaac Beeckman proposed an experiment wherein the flash of a cannon was reflected by a mirror, about a mile away, and the time lapse measured. Galileo independently proposed a similar experiment, in 1667. No time delay was detected.

With our modern knowledge of light’s

Dutch mathematician Christiaan Huygens used this to estimate a speed for light of about 220,000km/s, about 70 per cent of the modern value.

The next step in the story again involves astronomy, and the aberration of light. Rain that is falling vertically when you are at rest appears to be falling from a point in front of you as you walk forwards – you have to tip your umbrella to keep dry. Walk in the opposite direction and the origin of the raindrops now also appears to be in the opposite direction. Now think of the falling rain as light travelling from a distant star, and your motion being that of the Earth through the heavens. The apparent position of a star varies during the year due to this phenomenon, known as aberration.

James Bradley, the Astronomer Royal, discovered this phenomenon in 1729. He deduced that light travels about 10,200 times faster than the Earth in its orbit, 295,000km/s, an estimate that is within about two per cent of the modern value.

Back down to Earth To determine high speed requires either

How fast light can travel is a question that scientific minds

have been grappling with since ancient Greece. Today we can

measure the speed of light very precisely but, as this article

explains, it took hundreds of years and lots of theories to

get to where we are now.

THE

speed, we know it would have taken about one hundred-thousandth of a second for it to make the round trip. That’s less than the reaction time of the observers, hence their inability to measure any delay – the distances involved were simply too small. By contrast, the distances between the planets are so large that light takes several minutes to travel between them.

In Paris, Giovanni Cassini had been observing the moons of Jupiter, which in their orbits disappear behind the planet and reappear later. His measurements varied, and he attributed this to light having a finite speed. Danish astronomer Ole Rømer joined Cassini, and in 1676 noticed that the time that Io, Jupiter’s innermost moon, takes to reappear is less when the Earth is approaching Jupiter than when it’s receding from it. This confirmed Cassini’s conjecture – when Earth is approaching Jupiter, it has moved nearer while the light is en route, and the total distance for the light to travel is less. Hence it arrives relatively early. Rømer’s measurements and his discovery of the correlation with Earth’s motion cause him to be credited with the discovery. In 1690,

> IN A NUTSHELL

SPEED OF LIGHT

It’s the universal speed limit and the key to making sense of the Cosmos, but how did scientists discover how fast light can travel?

BY PROF FRANK CLOSE

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40 Earth’s Frozen PastUncover the mysteries surrounding the chilling Ice Age theories

36 The Speed Of LightIf you can see it then you’ll understand that the speed of light measures 299,792,458 metres per second

28 What Powers The SunWhat is the secret behind the Sun’s endless source of energy?

32 The Age Of The EarthHow old do you think the Earth really is? Read on to learn about the magical number

44-55 More Of How Do We KnowInside accounts on unravelling the mysteries of The Missing Elements, The Structure Of The Atoms and How The Continents Formed

hroughout the history of chemistry, the discovery of a new element has been regarded as an important

event and much credit has been granted to those who made such a find. Two major scientific breakthroughs then placed important constraints on the search for new elements, while still leaving plenty of scope for controversy.

The first of these major discoveries was the periodic table, that wonderful system of classification that serves to bring order to the elements while placing them into families of groups with similar properties. The periodic table was independently formulated by at least six scientists in different countries. The most famous of these was the Russian chemist, Dimitri Mendeleev, who in 1869 succeeded in accommodating the 63 elements that were known at the time into a coherent system.

In addition, Mendeleev had the audacity to predict the existence, and even the properties, of several new elements that would fill the empty spaces in his periodic table. His three best-known predictions were for elements that he called eka-boron, eka-aluminium and eka-silicon.

after tellurium. As a result of such irregularities it was not

clear whether any more elements existed between, for example, hydrogen and helium.

This brings us to the second major discovery, which resolved most of the outstanding issues about missing elements. In 1913 an English physicist, Henry Moseley, found that a better means of ordering the elements was provided by an ordinal number derived from his experiments with X-ray spectra (see ‘The key experiment,’ pxx) that ran from 1 for hydrogen to 92 for uranium. Each element had its own ordinal number, that soon became known as its ‘atomic number’. Unlike the atomic weights for each element, there were no fractional values and so there were no longer any ambiguities.

At this point the hunt for missing elements became more focused and it became clear that precisely seven elements remained to be discovered between the original boundaries of the periodic table from elements 1 to 92. The missing elements had atomic numbers of 43, 61, 72, 75, 85, 87 and 91.

Once discovered, they were given the names scandium, gallium and germanium respectively.

Weight problemsHere was the first signpost for how we know if elements are missing. If gaps were present in the periodic table, it meant that certain elements still awaited discovery. But things are not quite that simple, especially when dealing with the heavier elements.

The problem was that the periodic table originally ordered the elements according to their increasing atomic weights. But it turns out that subsequent elements in the table do not differ by a constant value of atomic weight. For example, the atomic weight of hydrogen is 1.008, that of the next element helium is 4.003 and the next element lithium has atoms with a weight of 6.941. There are even some ‘monster cases’ where two elements actually fall in the wrong order according to their atomic weights. For example, the element iodine has a lower atomic weight than tellurium and yet according to its chemical and physical properties it should appear

Once the periodic table had been discovered, the race was on among scientists to find the missing pieces in the puzzle…

BY DR ERIC SCERRI

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MISSINGELEMENTS

Elements are the building blocks of the natural world. The first periodic

table, a system describing all known elements, was produced in 1869,

revealing that a number were yet to be discovered – and scientific glory

awaited those who could isolate them.

> IN A NUTSHELL

Building the periodic table we know today involved a certain amount of filling in the gaps

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HOW DO WE KNOW?

> IN A NUTSHELLToday, the concept that the

continents sit on moving plates – and that earthquakes and

tsunamis are caused by those plates shifting – is common

knowledge. But while such ideas were first put forward in the 1500s,

it wasn’t until the 1960s that the theory of continental drift was

conclusively proven.

Once scientists discovered that the continents were once joined together, the race began

to explain how they drifted apart

BY DR CHERRY LEWIS

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CONTINENTS FORMED

HOW DO WE KNOW?

90

that Wegener’s mechanism to explain this was physically impossible. The British geologist, Arthur Holmes, was one of the few who favoured continental drift. In December 1927 he wrote a ground-breaking paper, postulating that differential heating of the Earth’s interior, generated by the decay of radioactive elements within it, caused convection in the substratum beneath the crust. Although the substratum appeared solid, Holmes believed that over vast periods of time it behaved like a very thick, hot liquid; as hot material reached the top of a convecting cell beneath a continent it would travel horizontally, producing a force that was sufficient to slowly drag the continents apart, allowing the substratum to rise into the gap and form new ocean floor. This convection, Holmes claimed, was the mechanism that drove continents around the globe.

Underwater worldIn the 1950s, groups collecting magnetic data from the ocean floors found a surprise beneath the Pacific: a pattern of linear magnetic stripes on the ocean floor that mirrored each other either side of

determined to start looking for evidence to support it.

In 1912 he felt confident enough to give his first lecture on the subject, publishing The Origin Of The Continents And Oceans in 1915. The book stated that during the late Palaeozoic era (about 350 million years ago) all the continents had been grouped together in one vast supercontinent he called Pangaea. As Pangaea started to break up, the continents slowly drifted apart, eventually arriving at their current positions. Some of the most convincing evidence was the palaeontological data. Not only did the tropical flora of the coal measures demarcate the equator of Pangaea, but Glossopteris ferns of the Permian era, which grew in a polar climate, were shown to cluster around Pangaea’s South Pole. In both Britain and America, Wegener’s ideas were received with incredulity and disbelief.

Although most geologists saw the logic of Wegener’s arguments, there was one question that could not be answered. Just how did the continents move?

Geophysicists in particular complained

ver since maps were made, people have noticed how the east coast of the Americas looks like it once

fitted snugly into the west coast of Africa and Europe – it isn’t a perfect fit, but it’s good enough to make many wonder whether they had once been joined together. As early as 1596, Dutch map-maker Abraham Ortelius considered that the Americas had been ‘torn away from Europe and Africa… by earthquakes and floods’.

But it was Antonio Snider-Pellegrini who in 1858 first reconstructed the continents as they might have looked before the split.

The Earth movesAlfred Wegener was a German meteorologist who, in 1910, was working at Marburg University in Frankfurt. On Christmas, as he and his roommate poured over the latest edition of a colour atlas, a thought occurred to him: “Does not the east coast of South America fit the west coast of Africa as though they had been contiguous in the past?” Wegener was so inspired by this revelation that he

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ome 400 years BC, in Ancient Greece, Democritus asserted that all material things are made from

tiny basic objects – atoms – that cannot be divided into smaller pieces. This was until Aristotle rejected atomic theory and the idea was ignored for nearly two millennia.

The Ancient Greeks also believed that everything was made from a few basic elements. Today we know that everything is made from chemical elements, such as hydrogen, carbon and oxygen. Today we also know that an atom is not the smallest thing: atoms are themselves divisible.

If you cut into an atom of any element, you will find its common constituents: lightweight, negatively charged electrons in the outer regions and a positively charged nucleus, dense and massive, at the centre. The only difference between the atom of one chemical element and another is the amount of electric charge on its nucleus, and the number of electrons that can be ensnared by the rule: ‘opposite charges attract’.

An atom of hydrogen, the lightest element, has a nucleus with one unit of charge, encircled by one electron. Helium,

had discovered that the weights of the various elements involved in chemical reactions were always in simple numerical proportions. The simplest example involved the gases, hydrogen and oxygen, combining to make water.

Careful measurements showed that if all of the gases were to be used and none left over, the weight of the oxygen would need to be eight times as much as that of hydrogen. As two hydrogen atoms and one oxygen atom have combined to make a molecule of water – H

2O –

this implies that one oxygen atom must weigh eight times as much as two atoms of hydrogen. Relative to hydrogen, atoms of oxygen, carbon, calcium and iron weighed 16, 12, 40 and 56 times as much. This tantalising numerology was a hint that the atoms of the heavier elements having ‘more’ of the mystery material than the lighter ones. In other words: atoms are made of something even smaller.

With hindsight, by the middle of 19th Century two discoveries held the clue that atoms have an inner structure. First was the phenomenon of atomic

> IN A NUTSHELL

From the first philosophical forays into the make-up of matter in Ancient Greece to the 20th Century’s exploration of quantum theory, find out about the pioneering physicists and the ground-breaking experiments that have shown us the workings of the atom.

THE

STRUCTURE OF THE ATOM

Throughout history, we’ve endeavoured to find out what things are made of at the smallest scales of matter. Thanks to great scientists we now know the answer…

BY PROF FRANK CLOSE

S the next, has two, and the heaviest naturally occurring element, uranium, has 92. Obtaining this knowledge took scientists on a remarkable journey of discovery.

Atomic alchemyIn the 17th Century, Robert Boyle founded the atomic theory of matter; he was the first to recognise that substances are compounds of basic elements, and to propose that these elements are composed of basic particles: atoms. Boyle’s ideas were descriptive only. Quantitative chemistry came about in the late 18th Century when Antoine Lavoisier showed that the masses of individual elements stay the same – are ‘conserved’ – during chemical reactions. This led to the idea that basic elements were rearranging themselves in such processes.

Mass effectIn early 19th Century England, John Dalton suggested that all atoms in a given chemical element are exactly alike: the atoms of different elements being distinguished by their mass. He

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94 Puzzle PitPuzzles, brain teasers and more that will entertain and boggle your mind

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FEATURESOn THE cOVEr

26 How Do We Know Unlocking the answers to the known and the unknown in the Universe

56 Portfolio: The Private Life Of GannetsThe calm outward appearance camouflages the spirited nature of the Gannets

63 Breakthroughs Of 2013 Know about never-before-seen innovations as 21st Century scientists reveal groundbreaking revelations that are set to change the world

70 Milestones That changed The World Tracing the most revolutionary inventions and ideas from the beginning of time

74 Measure Of All ThingsRuling the thermometer and clocking the weight, scientists re-define precision with these new-age measuring instruments

80 Game changers Recount the works of influential Indians that went down in history as the foundations of modern India

84 inside The PagesAn excerpt from Abhimanyu Singh Sisodia’s Ravana - Roar Of The Demon King tells the tale of how Ravana came to be known as the 10-headed rakshasa

88 The Big ideaDavid Norman investigates the events that made us bid adieu to the dinosaurs

Contents

18 SnapshotShort circuit of a high power laboratory

80 Game changersIndividuals who shaped modern India

4 December 2013

98 Gadgets10 gadgets that made our must buy list of 2013

14 updateGet ready to welcome Apple’s

new touchscreen car dashboard

REgUlARS

8 Q&AEvery question needs an answer. You have a question? We help satiate your curious appetite

18 SnapshotFactual, engaging and informative insights into three magnificent photographs

92 in EducationChief Education Officer of Aditya Birla Public School, Shayamlal Ganguli, talks about reforms needed in the education system

94 Puzzle Pit A veritable buffet of brain teasers guaranteed to test your mind

97 Edu Talk Dr N C Wadhwa, Vice Chancellor of Manav Rachna International, talks about moral education and Indian values

98 Gadgets Read and buy! The have-to-have gadgets

of 2013

UPDATE14 Latest intelligenceHave scientists found a way to make humans levitate?

RESoURcE100 reviewsWebsite picks from the world of science, history and nature

101 Games reviewWe look into the gaming world and bring you the latest picks

102 The Last WordOlympic winner and youth icon, Saina Nehwal talks about her can-do spirit

88 Big ideaWhat killed the dinosaurs? Investigating the events that led to their extinction

91 Happiness WallRead what makes our readers happy

84 inside The PagesAn excerpt from the graphic novel, Ravana - Roar Of The Demon King that explores the origins of the Lanka king

74 Measure Of All ThingsThe gen-next innovation of the common precision tools

56 PortfolioPoised predators - The Gannets70

MilestonesRetrace your steps through history’s game changing innovations

industrial revolution

telephone

zero

democracy

internet

DEcEMBEr 2013

wheel

money

Have you ever wondered if it is important to ‘know’ a lot of stuff about the world, or is it more important to be curious about it? Interestingly, our 3rd Anniversary issue holds the answer.

This edition is a celebration of the curious minded and their insightful journeys. It is a celebration of the innovators, inventors, discoverers who just wanted to know what lay ahead. Risk-takers who dared convention and searched for that something ‘more’. And it is their unease with the status quo that lead to the fundamental knowledge of what constitutes our world…What Powers The Sun, The Structure of The Atom, Earth’s Frozen Past, How The Continents Formed, The Missing Elements etc.

But this Anniversary issue is also a digest – of knowledge learned over centuries crunched into a few pages. So brace yourself. For the How Do We Know? specials. For the Milestones That Changed the World (pg 70) that show you how the world progressed - from the invention of the wheel to the advent of mobile banking. For India’s Game Changers (pg 80) whose decisions keep shaping our daily lives today. And for the Breakthroughs of 2013; big movements in the field of science that are set to shape our daily lives in the future.

As I said, brace yourselves.

Enjoy.

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From the editor

ENjOY YOUR FAvOURITE MAgAzINE wHEREvER YOU AREinDiA • Editor: Preeti Singh • www.knowledgemagazine.in ASiA • Editor: Ben Poon • www.regentmedia.sg/publications_bbc.shtml BrAziL • Editor: Cáren Nakashima • www.revistaconhecerbbc.com.br BuLGAriA • Editor: Hristo Dimitrov • www.knowledge.bg SWEDEn • Editor: Jonas Berg • www.bbcknowledge.se TAiWAn • Editor: Hui-Wen Lan

6 December 2013

Knowledgemagazineindia KnowledgeMagIND

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Send uS your letterSHas something you’ve read in BBC Knowledge Magazine intrigued or excited you? Write in and share it with us. We’d love to hear from you and we’ll publish a selection of your comments in the forthcoming issues.

Email us at : edit.bbcknowledge@wwm.co.inWe welcome your letters, while reserving the right to edit them for length and clarity. By sending us your letter you permit us to publish it in the magazine. We regret that we cannot always reply personally to letters.

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Experts this issueAlexander Hellemans writes about physics, astronomy, and science policy in various international journals. in this issue, he sheds light on What Powers The Sun. See page 28

Dr cherry Lewis, is an award-winning geologist and author of The Dating Game: One Man’s Search for the Age of the Earth. in this issue, she talks about The Age Of

The Earth and How The continents Formed. See page 32

Frank close is the best-selling author of the Antimatter, and the winner of the Kelvin Medal of the institute of Physics, uK. in this issue, he traces The Speed Of Light and de-constructs The

Structure Of The Atom. See page 36

John Gribbin is a writer, an astrophysicist and a visiting fellow in astronomy at the university of Sussex, uK. He has written a book, In Search of Schrödinger’s Cat: Quantum Physics and Reality.

in this issue, he reveals Earth’s Frozen Past. See page 40

Dr Scerri is a chemist, a leading philosopher of science specialising in the history and philosophy of the periodic table. in this issue, he helps you connect the dots to The Missing

Elements. See page 44

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SCIENCE • HISTORY • NATURE • FOR THE CURIOUS MIND

7February 2013

HERE’S HOw TO gET IN TOUCH

Team IndIaChief Executive Officer Tarun rai

Editor Preeti SinghFeatures Editor Kamna Malik

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KnoW SPot

The first planet to orbit to stars, like Luke Skywalker’s home of Tatooine in Star Wars is Kepler-16b.

8 December 2013

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bbcknowledge@wwm.co.inQA& Your Questions Answered

experT paneLStuart Blackman A zoologist-turned-science writer, Stuart is a contributor to BBC Wildlife Magazine. Susan Blackmore (SB) A visiting professor at the University of Plymouth, UK, Susan is an expert on psychology and evolution. Alastair Gunn Alastair is a radio astronomer at Jodrell Bank Centre for Astrophysics at the University of Manchester, UK. robert Matthews Robert is a writer and researcher. He is a Visiting Reader in Science at Aston University, UK. Gareth Mitchell As well as lecturing at Imperial College London, Gareth is a presenter of Click on the BBC World Service. Luis Villazon Luis has a BSc in computing and an MSc in zoology from Oxford. His works include How Cows Reach The Ground.

ASK the exPertS?Email our panel at bbcknowledge@wwm.co.in We’re sorry, but we cannot reply to questions individually.

How do climbing plants climb?Climbing is a parasitic behaviour that saves a plant the effort of making a strong trunk or stems of its own. There are several distinct strategies. Ivy uses specialised roots that work into tiny fissures in tree bark or a wall, while clematis has leafstalks that twist around the stems of another plant to anchor it as it grows. Cucumber plants have tendrils that wrap around another stem and then pull the plant up by coiling up the tendrils.

Climbing plants normally start by creeping along the floor until they reach a stem. Although the point of climbing is to escape the shade, some tropical climbers begin by growing away from the light, because this makes them more likely to reach a tree trunk. Once they touch something, the physical contact triggers chemical changes that stimulate the climbing behaviour and the plant begins to grow against the direction of gravity. LV

bbcknowledge@wwm.co.in

HIgHlIgHTS E Do ants have feelings? p9 E How do sinkholes form? p10 E Does a full e-book weigh more than an empty one? p12 E Can the world’s tallest skyscraper be built in 90 days? p13

What eventually happens if you’re not much of a gardener

Do ants have feelings? Ants don’t have complex emotions such as love, anger, or empathy, but they do approach things they find pleasant and avoid the unpleasant. They can smell with their antennae, and so follow trails, find food and recognise their own colony. Their exoskeleton has sensory hairs on the outside but they probably cannot feel damage on the inside, which is why parasites can destroy them if they can get in without touching the sensors.

Each ant’s brain is simple, containing about 250,000 neurones, compared with a human’s billions. Yet a colony of ants has a collective brain as large as many mammals’. Some have speculated that a whole colony could have feelings. SB

Earth is losing 50,000 tonnes of weight a year

Is Earth gaining or losing mass?Scientists estimate that the Earth gains about 40,000 tonnes of material each year in the form of dust from space. They also estimate that about 95,000 tonnes of hydrogen gas are lost from the Earth’s atmosphere each year. The Earth is therefore losing at least 50,000 tonnes of mass every year.

While this might seem a lot, with a total mass of about 6 septillion kg (6x1024kg), it would take about 120 thousand trillion (1.2x1017) years for the Earth to disappear with that rate of mass loss. That’s more than 8 million times the age of the Universe! AG

Is my brain more active at night or during the day?

A sleeping brain is not resting. A 2010 study at Harvard found that the levels of ATP (the chemical used to provide energy to cells) in the brain remain fairly constant while you are awake, but briefly surge when you fall asleep. Rather than resting the brain back to full strength, sleep provides it with an initial energy boost.

This increased energy is used up through the night to create and rearrange the connections between neurones. So while some regions may be less active, your brain uses more energy overall while you sleep. LV

You may be up to more when you’re asleep

than you think…

It’s lucky that ants don’t experience

annoyance at overcrowding

9December 2013

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10 December 2013

How do sinkholes form? There are two main processes. Either a cave gradually enlarges until the roof falls in, or a top layer of sand and soil is washed by rainwater into fissures in the underlying rock, eroding it away before it collapses leaving a hole.

Both kinds are normally found in limestone areas because limestone is slightly water soluble and forms the kind of caves and fissures that are required. Sinkholes can be triggered by sudden storms or flash floods and are also sometimes the result of old mine works.

Florida is particularly prone to sinkholes because of an underlying system of limestone caverns, while in 2010 a sinkhole in Guatemala City was big enough to swallow a road and an accompanying three-floor building. LV

Why are solar eclipses rarer than lunar eclipses?

Solar eclipses are not actually rarer than lunar eclipses – in fact, they occur in about equal numbers, usually about two of each per year. For example, between 2000BC to 3000AD there will be 11,898 solar eclipses and 12,064 lunar eclipses. However, at any one location on Earth, it is much less common to see a solar eclipse than a lunar one. And the reason for this is entirely due to geometry.

A lunar eclipse, when the Moon moves through the shadow of the Earth, is visible from wherever the Moon is above the horizon, which is over half of the Earth. However, when the

Moon appears to move in front of the Sun during a solar eclipse, the shadow cast by the Moon is much smaller than Earth. It’s only about 480km (300 miles) wide when cast onto the Earth’s surface.

What colour is the Martian sky?

On earth, the sky appears blue because atmospheric molecules scatter blue light more than other wavelengths. If the Martian atmosphere were clear like Earth’s, the Martian sky would also appear blue or indigo – though it would be deeper in colour than Earth’s, due to Mars’s much thinner atmosphere.

But Mars’s atmosphere contains a permanent haze of dust particles composed mainly of iron oxides such as limonite and magnetite, the same minerals that give the planet’s surface its characteristic red colour. This haze preferentially absorbs blue light and results in a yellow-brown sky, often described as ‘butterscotch’. At sunset and sunrise the sky can appear pinkish-red because there is more absorption of blue light due to the increasing hickness of atmosphere through which sunlight is travelling. AG

Mars’s sky is a ruddy brown, as this image from

NASA’s Curiosity rover reveals

Solar eclipses are therefore only visible from within a narrow path across the Earth, making it difficult to get to a location to see one. This is why they are visible less often from any given location. AG

A sinkhole in Guatemala

City Should have had a

survey done…

A total solar eclipse only casts a shadow about

480km wide across the face of the Earth

Your Questions Answered

bbcknowledge@wwm.co.inQA&

Nasa’s asteroid Catcher

hOw it wOrks

If you’ve ever struggled to cram all your shopping into a bag to get it home again, then spare a thought for NASA, which is going to need a very big bag indeed for its latest purchase.

In April NASA announced a mission to capture an asteroid and tow it back to Earth, parking it near the Moon. But how do you go about capturing a 500-tonne spinning lump of rock and ice?

The plan is to send a small, unmanned, solar-powered probe to intercept the asteroid, a journey that will take nearly four years. Once there a high-strength inflatable bag will be deployed around the space rock, held open by four or more inflatable arms linked together with hoops. Cinching cables would then be used to pull the bag up against a ring that constrains the asteroid’s position and attitude. This would

bring the space rock’s centre of mass close enough to the probe’s thrusters that they can then be used to stop the asteroid spinning.

The probe will then park the asteroid at a Lagrangian point (an area of space where the gravity between two masses is balanced) between the Earth and the Moon, to prevent it from wandering off. The asteroid will then be studied by astronauts using an Orion spacecraft, which should be ready to launch by 2021 to meet President Obama’s target of landing man on an asteroid by 2025. The craft will have a robotic arm to attach to the asteroid, as the space rock is too small to land on directly.

The project will also allow NASA to test measures for diverting future asteroids on a collision-course with Earth.

THRUSTERS

15m

MAIN SPACECRAFT

CAPTURE BAG DEPLOYED

1. Following launch the aster-oid catcher starts a 2.2 year journey before a slingshot from the Moon sends it into deep space.

3. …before engulfing the asteroid.

4. The asteroid is parked in a stable orbit around the Moon after a 2-6 year journey.

2. After an-other 1.7 years the capture bag is deployed…

SOLAR ARRAY

A human (to scale) would be dwarfed by the asteroid capture

10m

Your Questions Answered

bbcknowledge@wwm.co.inQA&

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12 December 2013

Is Einstein the smartest person who has ever lived?

Your instinct would be to say no. Electrons have mass, but when they’re used to store data, only their arrangement changes. The number of electrons remains the same. However, the University of California, Berkeley professor John Kubiatowicz refers to the way that electrons are trapped through a mechanism called tunnelling. Each cell of memory in an e-book contains two gates separated by an oxide layer. When data is stored a charge is applied, unleashing a torrent of electrons flowing from one side of the layer to the other, where they remain lodged until another charge is applied. Being trapped increases the electrons’ energy. From Einstein’s E=mc2 in which energy and mass are equivalent, the e-book becomes slightly heavier.

A full Kindle would be an un-measurable billionth of a billionth of a gramme heavier than a brand new one. GM

Does a full e-book weigh more than an empty one?

Einstein has become synonymous with brilliance, and he’s certainly one of the greatest scientists of all time. But it’s hard to claim he’s the smartest person who ever lived. It’s often said (with scant evidence) that his IQ was 160; even if true, that would make him less intelligent than thousands of people alive today. In terms of mathematical ability, Einstein would not come close to matching today’s leading physicists like Stephen Hawking.

The depth and range of his achievements are not without precedent, either. Far less well-known scientists such as Carl Gauss and Leonhard Euler made fundamental contributions in many more fields. The person with perhaps the strongest claim to being the smartest person of all time is the Victorian polymath Sir Francis Galton, whose work on everything from statistics and evolution to the ‘wisdom of crowds’ is still used every day by researchers a century after his death. RM

Einstein: not so smart after all?

How do USB flash drives hold so much data?Flash storage devices are based on chip technology called Electronically Erasable Programmable Read Only Memory (EEPROM). USB flash sticks use a refined version of

EEPROM. In its earliest incarnation, individual bits of data on the chip had to be erased separately. It was like a vertically stacked library where getting at one book at the

bottom of a pile meant having to move the books above it one at a time. But now multiple memory cells can be addressed simultaneously, allowing entire blocks to be written and rewritten in one go, like moving a pile of books, rather

than one book, at a time. It requires considerable on-chip processing and is a feat that has come about through recent advances in chip design and

miniaturisation, ushering in USB drives capable of storing gigabytes of data. GM

Flash drives, thumb drives, pen drives… whatever they’re called they store a lot of data

E-readers have replaced heavy tomes, but are they heavier when full?

13 June 2013

hOw it wOrks

OctOber 2012 / FOcUS / 13

World’s Tallest Building When it’s complete the Chinese skyscraper Sky City will be the tallest structure on the planet, but this isn’t the behemoth’s most remarkable fact. The current tallest building in the world, the 829.8m-high Burj Khalifa in Dubai, took six years to build; China wants to throw up a building nearly twice as high as the Empire State Building in just three months!

The feat is being attempted by Broad Sustainable Building, which will erect Sky City in the city of Changsha, starting in January. The company will employ the same techniques it previously used to construct a 15-storey hotel in just 48 hours. Modules containing the floors, pillars, walls and tools are put together in a factory, before being carried to the site (two per lorry), where they’re put together like a giant Meccano set.

Once complete, it will dwarf the surrounding buildings at 838m high and have a hospital and apartments to house 30,000 people.

FLAT-PACKED SKYSCRAPERA module consists of a floor section with flat-packed walls and the columns needed to support another module placed on top. Plus bolts that stick it all together.

copy in here copy in here copy in here copy in here copy in here copy in here copy in here copy in here copy in here copy in here copy in here copy in here

Modules are hoisted up on a crane and put together. To build Sky City in 90 days, modules will be stacked on top of each other to build five storeys a day, reaching a grand height of 220 storeys.

14 December 2013

E Can you grow your own teeth using your own urine? p15 E Are humans evolving to fight off an attack of cholera? p16 E Is Apple Inc in the process of making an iCar? p16

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loating coffee beans, dancing water droplets, flying

toothpicks – if you walked into one Swiss laboratory, you’d be forgiven for thinking you were seeing things. For the first time, scientists have found a way to move and manipulate objects in mid-air using sound waves. The breakthrough means ‘acoustic levitation’ can be used to create new materials, carry out delicate experiments, and even, in theory, levitate humans.

Acoustic levitation was invented by NASA in the 1980s but until now, scientists could only hold an object in place or rotate it on the spot. Now researchers at the Swiss Federal Institute of Technology in Zurich have developed a way to move objects and handle more than

F one at the same time.The system uses vibrating

square platforms, each about the size of a thumbnail, that send out sound waves and reflect them off a surface above. At certain frequencies, the reflected waves combine with the upwards-moving waves to create a pattern known as a ‘standing wave’. This has certain points, or ‘nodes’, that stay fixed even as the wave oscillates. An object placed at one of these sweet spots can float in mid-air, with the force from the sound waves balancing the downwards pull from gravity.

By lining up a series of platforms and varying the strength of the sound waves from one to the next, the researchers can carry objects from platform to platform. To demonstrate, they dissolved

a floating coffee granule by moving it into a droplet of water and even levitated a toothpick. “Our idea was to pack levitators close together, and then try to ‘pass the ball’ from one to the other,” says Dr Daniele Foresti, who led the research.

To generate enough lift, the system blasts out sound waves at 160 decibels – about the same volume as a jet engine at close quarters. That’s why the researchers use ultrasonic waves with a frequency of 24,000Hz, which is too high for humans to hear.

The acoustic levitator could allow scientists to move hazardous chemicals without touching them, handle cells without risk of contamination, and manipulate liquids that have been cooled below their freezing point. “Supercooled liquids tend to start freezing as soon as they touch a container,” says Foresti. “By levitating them, we can keep them as liquids. For example, we could use our system to bring together two supercooled metals and create new kinds of alloys.”

Technique uses sound waves to float objects and carry out experiments

Coloured drops of fluid are levitated by the

revolutionary sound wave experiment

A toothpick is moved around in the air on top of sound wave platforms

A sound new way to levitate

Floating coffee beans, dancing water droplets, flying toothpicks – if you walked into one Swiss laboratory, you’d be forgiven for thinking you were seeing things. For the first time, scientists have found a way to move and manipulate objects in mid-air using sound waves. The breakthrough means ‘acoustic levitation’ can be used to create new materials, carry out delicate experiments, and even, in theory, levitate humans.

Update THe lATesT InTellIgenCe

15 December 2013

D

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Strongest signs yet of life in Antarctic lake

Vostok Station doesn’t look like much, but it’s

discovered an ecosystem under the Antarctic ice

Direction of ice flow

Vostok Station

Core drilled down to 3,623km

Lake Vostok

Direction of ice flow

espite being cut off from the rest of the world for millions of years, there are

strong signs that Antarctica’s Lake Vostok is teeming with life. Samples of ice from just above the subglacial lake have been analysed, revealing traces of thousands of species. But researchers are stopping short of saying that this provides definitive proof of life in the lake.

Lake Vostok is the largest of hundreds of Antarctic lakes and is covered by 4km of glacier ice. Last year, Russian scientists succeeded in drilling down through to the lake for the first time, collecting water samples which are currently being analysed.

In the meantime, biologists at Bowling Green State University in Ohio analysed a sample of ‘accretion ice’ extracted in 1998 that would have formed as the lake froze. They have identified 3500 unique genetic sequences. Most are from bacteria,

though some belong to multicellular organisms. The research, published in the journal PLOS ONE, has led to criticism that the samples may have been contaminated.

“I don’t think you can assure with 100 per cent certainty that you don’t have some contamination,” says Dr Scott Rogers, who was involved with the research. “[But] we used very stringent procedures, and just looking at the organisms that we had in our sample, I think it’s nearly impossible that they could have come from contamination.”

Earlier this year, life was discovered in another Antarctic lake, Lake Whillans, although that one is buried under just 800m of ice. Scientists searching for life on other planets, where the conditions may be similar to those in Lake Vostok, will take a keen interest in this new research. “Planetary scientists should be encouraged by what we’ve found,” says Rogers.

South Pole

Lake Vostok

ANTARCTICA

grow your own teeth…with urine

entists may one day be able to grow you a replacement tooth using a very unlikely source – your urine. Researchers in China

have transformed cells discarded in urine into stem cells that can grow into tooth-like structures. The technique could provide a source of new teeth built from a patient’s own cells.

Researchers led by Duanqing Pei, an expert in regenerative medicine at the Chinese Academy of Sciences in Beijing, harvested cells from human urine and then converted them into pluripotent stem cells – cells that have the potential to develop into any other cell.

These stem cells were mixed with molar dental tissue from mouse embryos and then transplanted into the kidneys of a different group of mice. After three weeks, tiny structures that resembled teeth had grown inside the mice’s kidneys. What’s more, their structure was similar to human teeth, containing the central part of a tooth (pulp), the layer between the pulp and the enamel (dentin), and the hard surface (enamel). The researchers say that if human dental tissue was used instead of mouse tissue in the development process, the technique could, in theory, be used to develop a wholly human tooth bud that could be transplanted into the jawbone of a patient.

On the downside, the experiment only had a success rate of around 30 per cent and the artificial gnashers weren’t as hard as real human teeth. “So far, the researchers have only been able to grow tiny teeth in mice,” says Professor Anthony Hollander, Head of the School of Cellular and Molecular Medicine at the University of Bristol. “Functional human teeth need to be full-size and matured.”

So, for now at least, we should be trying to preserve the set we already have.

Missing a tooth? Soon you may just have to supply a

urine sample at the dentist’s to get a new one

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KEEPInG ABREAST Of THE TOP ScIEncE, HISTORy AnD nATURE RESEARcH fROM AROUnD THE WORLD

THe lATesT InTellIgenCeUpdate

Inhabitants of the Ganges Delta are

evolving resistance to cholera

HumaN EvoluTioN iN aCTioN

Cholera may cause thousands of deaths a year, but the human body is evolving to fight back. The genomes of people from the Ganges River Delta region in Bangladesh, where the disease is rife, have been compared with people from northwestern Europe. Over time, cholera appears to be changing the genetic code of Bangladeshis so people are more resistant to it.

Having revolutionised the computers in our homes, Apple now wants to redesign the dashboards in our cars. The technology giant has come up with a ‘Digital Dash’ in which the usual cluster of knobs and dials in front of the driver is replaced with a large touchscreen.

But this won’t simply be an iPad embedded in the dashboard. To keep the driver’s eyes on the road, the tactile display will allow the driver to ‘feel’ whatever they’re touching by sending pulses of acoustic waves to their fingertips. The

system may also include a head-tracking camera so the driver can nod up and down to make selections.

The patent, which has been granted, lists a plethora of possible functions that could be controlled or displayed on the screen. These include interactive maps, parking aids, voice access to email, an infrared night vision display, climate control, games for the passengers and even a maintenance screen featuring performance data and photos of key parts of the vehicle.

Taking photos with a handheld camera is all well and good, but landscapes sometimes look a lot more interesting from the air. The Squito could be the answer. When this ball-shaped camera is tossed skywards, it can capture aerial shots of your surroundings.

Inventor Steve Hollinger in Boston, USA, came up with the design, which uses three cameras to take photos while it’s airborne. Onboard orientation and GPS sensors tag each photo with the ball’s precise location and position and a processor then automatically rotates and stitches the shots together into one seamless panoramic image or fly-by video. This is then sent wirelessly to your smartphone, tablet or desktop.

But the Squito isn’t just about improving

your holiday snaps – it could also be used in emergency situations. The device could be thrown into an unstable building, for example, to scout for earthquake survivors. The patent application has been granted.

APPLE’S DIGITAL DASHBOARD THE THROWABLE cAMERA

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16 December 2013

Snapshot

a school of tadpoles weaves its way through lily stalks in Cedar lake in central Canada.

“Tadpoles tend to school more in the presence of predators because individually they have a higher chance to survive an attack,” says

Dr Robert Jehle at the university of salford, a specialist in amphibians. But it isn’t just

about safety in numbers. “They are able to smell a food source so with their collective

sense of smell, they are more likely to find it,” says Jehle. Tadpoles are mostly herbivorous, scraping algae from hard surfaces. But they

are also happy to nibble on a dead animal. “schools are usually comprised of sisters and

brothers who come from the same egg clutch,” says Jehle. “There is evidence that they can recognise their own kin using their sense of

smell.” soon these tadpoles will lose their tails and develop legs and lungs to hop on land. as frogs they will lose their ability to

recognise their siblings.

Amphibian swarmSAFETY IN NUMBERS

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December 2013

Spheres of influenceGENERATING POWER

These huge orbs form part of a facility in ludvika, sweden developing the next generation of power transmission technology. at aBB’s High voltage laboratory, new pieces of equipment such as circuit breakers and transformers are put through their paces to test whether they can cope with high voltage transmission.

made of aluminium, the spheres sit on top of the test circuit. “They even out the electrical field preventing flashovers – short circuits through the air between different pieces of equipment,” says Björn Jacobson, an engineering manager. The spheres are part of an alternating current (aC) test circuit where equipment can be exposed to over one million volts. xx

x

SciEncESNAPSHOT

nATurESNAPSHOT

These turquoise gems rising up through the snowy landscape are shards of ice

above lake Baikal in siberia – the most voluminous freshwater lake in the world.

Fierce winds cause the ice to move, resulting in these stunning ‘hummocks’.

When ice has many imperfections, the full spectrum of light, or white light, is

scattered and reflected, giving it a white hue. But here, there are no bubbles to

interfere with the passage of light, so it penetrates undisturbed. “The red and

yellow parts of the spectrum tend to be absorbed by ice and water more than

the blues,” says climatologist Dr ignatius Rigor from the university of Washington’s

Polar science Center. “That’s why we see this brilliant blue colour.”

“This fresh water ice is much clearer than sea ice, which tends to trap salts in a

crystal lattice,” adds Rigor.

Icing on the lakeHUES OF BlUE

23December 2013

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www.knowledgemagazine.in Volume 4 Issue 1 December 2013 `100

SCIENCE • HISTORY • NATURE • FOR THE CURIOUS MIND

The SOF Challenge

To know more log on to Knowledge Magazine India

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SciEncE

How do we

know?find out how we solved the greatest

mysteries of our world

he nature of the Sun, and why it was glowing hot, remained unquestioned until the middle of

the 19th Century, when scientists started wondering how heat related to the power of steam engines. The French engineers Nicolas Léonard Sadi Carnot and Émile Clapeyron studied steam engines and were the first to create a new branch of physics: thermodynamics.

In the 1840s, the British scientist James Prescott Joule performed his famous experiments that supported Hermann von Helmholtz’s idea that mechanical motion, heat, and radiation are different manifestations of what he called ‘force’, which now corresponds to the modern concept of energy. With it came the realisation that any source of power, is finite, and scientists started to wonder what was the seemingly infinite source that powered the Sun.

Solar powerHelmholtz agreed with the views of philosopher Immanuel Kant and mathematician/astronomer Pierre-Simon Laplace that the Sun was formed by the

physicists Ernest Rutherford and Frederick Soddy soon identified it as radioactivity: atoms decaying by splitting up into smaller atoms. The mass of the newly formed atoms is less than that of the original atoms splitting up, and this tiny difference in mass is transformed into energy according to Einstein’s formula for the equivalency of mass and energy: E=mc2. Therefore, it was not surprising that Rutherford thought that nuclear fission, that produces heat inside the Earth and in nuclear reactors, could also heat up the Sun.

In the meantime, to astronomers, the Sun appeared as a huge ball of hydrogen with small amounts of elements, such as helium, oxygen and carbon. There was insufficient uranium or other heavy elements present in the Sun to enable nuclear fission reactions.

If atomic nuclei can split into smaller nuclei, why would smaller nuclei not be able to ‘fuse’ into bigger ones?

This was what the American chemist William Draper Harkins asked himself, and in 1915, proposed that the fusion of hydrogen atoms, forming helium atoms,

contraction of a huge gas cloud – a theory viewed as correct today. He argued in 1854 that the compression of the gas cloud caused the Sun to heat up, an idea defended by the British Physicist William Thomson (Lord Kelvin) until the 1890s.

Kelvin figured out that the Sun could not be more than 40 million years old, and he clashed with the geologists and biologists of the time. For example, Charles Darwin’s views on evolution required the Earth to be much older. By the end of the 19th Century, geologists had sufficient evidence that the Earth had to be more than a billion years old.

The first glimpse of a possible solution came American geologist Thomas Chrowder Chamberlin. He suggested in 1899 that “unrecognised sources of heat” may exist inside the Sun, energies of an “atomic or ultra-atomic nature”. Kelvin rejected this idea, but the discovery in 1903 of a weird property of the chemical element radium, recently isolated by the French physicists Marie and Pierre Curie, made Chamberlin’s idea acceptable.

The material had a mysterious heat source that kept it hot. The British

wHAT PoweRSTHe SUn

Until the 19th Century, no one had any idea how the sun produced energy. Understanding the atomic nucleus and the chameleon-like nature of an elusive

particle finally resolved the mystery

By ALExAnDER HELLEMAnS

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HoW Do WE KNoW?

28 December 2013

> In a nUTsheLLFind out how scientists made the

intellectual journey from believing that the Sun was powered by an endless

meteor bombardment, to discovering a nuclear reaction that stretched our

understanding of physics to its limits.

wHAT PoweRS

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The Key experImenTMAJOr nEW SciEnTiFic BrEAKTHrOuGHS OFTEn rEQuirE HuGE ExPEriMEnTS. THE SuDBury nEuTrinO OBSErVATOry iS A LArGE PiEcE OF EQuiPMEnT TO DETEcT SOMETHinG incrEDiBLy SMALL

The equipment that detected neutrinos from the Sun was the Sudbury Neutrino Observatory (SNO) in Ontario, Canada. It consisted of a ball-shaped container filled with 1000 tonnes of heavy water, in which hydrogen atoms are replaced by atoms of deuterium – a type of hydrogen having a proton and a neutron in its nucleus. The container was surrounded by a sphere consisting of 9500 photomultiplier tubes.

The neutrinos interacted with the deuterium nuclei, producing electrons. In one interaction, a neutrino hits a deuteron (a proton and a neutron forming the nucleus of a deuterium atom), and ejects an electron. In a second type of interaction, a neutrino kicks an electron out of an atom. These electrons travel in the liquid at speeds faster than the light does. In doing so they give off what’s called Cherenkov radiation, a cone of light that’s comparable to the sonic boom heard when an airplane breaks the sound barrier.

The photomultiplier tubes detected the light cones and their orientation. The fact that light radiated in the opposite direction from the Sun was proof that the neutrinos came from the Sun. The SNO not only distinguished between the three flavours of neutrino but also confirmed the results obtained by Raymond Davis.

Alexander Hellemans is the co-author of The History Of Science And Technology.

What Powers The sun

would also produce heat according to Einstein’s energy formula.

neutron bombIt was difficult to explain the stability of atomic nuclei heavier than hydrogen by assuming that they’re made up only of protons. They would repel each other, due to their electric charge. In 1920, Harkins, and independently Rutherford, predicted the existence of the neutron, an electrically neutral particle that had to be holding the protons inside the nucleus.

James Chadwick discovered this particle in 1932. This discovery made it possible to develop a theory for fusion reactions, and in 1939 the German physicist Hans Bethe developed nuclear fusion mechanisms that convert hydrogen into helium in the Sun and stars.

For low-mass stars, such as the Sun, Bethe developed the proton-proton mechanism. Protons (hydrogen nuclei) in the Sun’s core would collide with each other, due to the extremely high temperature. A quantum effect, called ‘tunnelling’, would help to overcome the electrostatic repulsion between the protons. The helium nuclei formed, consisting of two protons, would not survive. But Bethe found that if one of the protons changes into a neutron, the

nuclei, consisting of two protons and two neutrons, would not fly apart. The resulting helium nuclei would be lighter than the hydrogen nuclei that formed it, with the difference in mass being converted into heat.

However, this was only a theory. But then a new kid arrived on the block: the neutrino. It was found that a mysterious particle was carrying energy away in certain types of radioactivity, called beta decay. In the reaction, a neutron in an atomic nucleus converts into a proton and emits a beta particle. The energy of this beta particle was not constant, something had to be carrying energy from it.

Austrian physicist Wolfgang Pauli, one of the pioneers of quantum theory, suggested in 1930 that yet another unknown particle, this time with no mass, was emitted along with the beta particle. The Italian nuclear physicist Enrico Fermi christened this particle the neutrino – ‘small neutron’ in Italian. But unlike the neutron, neutrinos hardly interact with matter. Their existence was only confirmed experimentally in 1955.

Looking inside the SunOne type of beta decay, converting protons into the neutrons required to form helium nuclei, was thought to take place in a chain reaction inside the Sun. Neutrinos

should therefore be formed abundantly. Raymond Davis, an American physical chemist, decided to use a neutrino capture idea proposed in 1946 by the Italian-British physicist Bruno Pontecorvo. And in 1967, completed a huge neutrino detector in South Dakota. The first results, published in 1968, were puzzling: Davis detected three times fewer radioactive argon atoms than predicted by Bahcall. The problem became known as the ‘solar neutrino deficit’. In 1967, Bruno Pontecorvo predicted that solar neutrinos could change type (flavour). The Homestake experiment could only detect electron neutrinos, and Pontecorvo argued that a good number would go undetected.

Scientists started seriously questioning Bahcall’s computations. He finally got off the hook in 2001, when data from the Sudbury Neutrino Observatory (SNO) (see the key experiment below) in Canada, became available. The SNO used a huge tank with heavy water in which all three types of neutrinos could be detected. Not only did it confirm Bahcall’s neutrino flux computations, it also proved that neutrinos have mass.

Photomultiplier tubes at the Sudbury Neutrino Observatory surround a vast chamber filled with water to detect a fleeting glimpse of a neutrino

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December 2013

1906-2005 1934-20051824-1907 1913-1993 1914-2006

G William Thomson (Lord Kelvin) was a British physi-cist and one of the founders

of thermodynamics. He argued that the Sun was heated by the contraction

of a gas cloud, and was not more than 40 million years old, which was counter to mounting geological and

evolutionary evidence that the Earth was much older.

G Bruno Pontecorvo proposed the use of

chlorine atoms that would transmute into radioactive

argon atoms for the detection of neutrinos.

The Italian physicist also predicted that the three types of neutrino would

continuously change from one type into another.

Hans Bethe a German and American nuclear physicist, he received the Nobel Prize for Physics in 1967 for his research into the nuclear

reaction mechanisms in the Sun and stars. It resulted in

the accurate description of two different fusion reactions by

which stars convert hydrogen to helium.

G John Bahcall was an American theoretical physicist who predicted the production rate of neutrinos in the Sun.

The predicted neutrino flux was larger than that

measured by Davis’s Homestake Experiment but was confirmed in 2001 by results from the Sudbury

Neutrino Observatory.

raymond Davies set up the Homestake Experiment to detect

the neutrinos emitted by the Sun in collaboration

with John Bahcall. The American physical chemist detected fewer neutrinos than predicted

by John Bahcall, detecting only electron neutrinos.

iT TOOK THE BEST PArT OF A cEnTury TO Pin DOWn THE ExAcT MEcHAnicS BEHinD THE Sun’S EnDLESS SOurcE OF EnErGyTImeLIne

Wolfgang Pauli postulates the existence of an as-yet unknown neutral and massless particle, the neutrino. It would be emitted in certain nuclear reactions.

Hans Bethe and Carl von Weizsäcker (pictured) work out the two nuclear fusion mechanisms occurring in stars: the proton-proton reaction for smaller stars like the Sun and the CNO reaction cycle for larger stars.

Bruno Pontecorvo advances the idea that neutrinos change from one ‘flavour’ into another, a phenomenon known as neutrino oscillation. In 2001, data from the Sudbury Neutrino Observatory proved he was right.

Raymond Davis publishes his first results with his underground solar neutrino detector in the Homestake Mine in South Dakota. He detects only a third of the number of neutrinos predicted by John Bahcall in 1964.

19391930 1957 1968 2001

THE BiG-HiTTErS OF PHySicS WHO MAnAGED TO unrAVEL THE MySTEriOuS FOrcE POWErinG THE Sun CasT of CharaCTers

Data from the Sudbury Neutrino Observatory (pictured) confirms the existence of neutrino oscillations, showing that neutrinos have mass, and also confirms the results obtained by Raymond Davis and the computation of the neutrino flux by John Bahcall.

HoW Do WE KNoW?

THe

Age of THe eARTH

By DR cHERRy LEWIS

oday we know that the Earth is 4.54 billion years old, plus or minus one per cent. It’s a number

that has changed little since it was first determined 57 years ago, back in 1956 – only the error has got smaller. But how can we be so certain that it is accurate and why did it take so long to find it? To answer those questions we must turn the clock back three centuries.

Archbishop James Ussher was just one of many scholars in the 17th Century attempting to establish the exact day on which God had created the Earth. Starting with Adam, Ussher developed a chronology for all the significant people in the Bible. He then added up their ages to determine that heaven and Earth were created on 23 October 4004BC, which was a Saturday. This date would have remained as unknown as all the others had it not been for an enterprising bookseller called Thomas Guy who recognised a demand for cheap, mass-produced Bibles. In 1675 Guy began printing a version that included Ussher’s chronology in the margins.

different places, ages calculated using these rates produced a broad range – from 3 to 2400 Ma.

The second hour-glass method attempted to measure the rate at which salt accumulated in the sea. Rivers hold dissolved salts in solution, derived from decomposition of the rocks over which they pass. Assuming that the sea had originally been pure water, they thought it should be possible to measure the time it had taken to accumulate present levels of salt. But this method was fraught with difficulties and also led to a wide range of ages.

Then in 1862, Lord Kelvin, a renowned physicist argued that the Earth had originally been molten and considered it ‘obvious’ that if the temperature at which rocks melted and the rate at which they had cooled down was known, then it should be possible to calculate the time at which the Earth’s crust had consolidated. Given these unknowns, Kelvin gave his estimate to between 20 and 40 Ma. There was uproar from the geologists.

The decade that straddled the turn

Spheres of timeAs knowledge about geology gradually accumulated, geologists began to realise that a few thousand years was just not long enough. In particular, a French Count, George-Louis Leclerc de Buffon, believed that the Earth and the planets had all originated simultaneously from a plume of intensely hot material torn from the Sun. Over a period of 11 years, Buffon conducted extensive experiments with spheres of iron and rock of varying sizes, and published his results in 1775, giving the age of the Earth as 74,832 years since its formation to its current temperature. Over the following century, evidence for the aeons of time needed for geological processes began to emerge from studying the rates at which they could be seen to be operating, and by the middle of the 19th Century two of these ‘hour-glass’ methods prevailed. The first attempted to estimate both the total thickness of rocks in the world and the rate at which sediments were deposited, which gave the time taken to deposit all the rocks. But because deposition rates are different in

It’s taken three centuries for scientists to pin down the age of our home planet, a complex task with a

cast of characters as diverse as its many experiments

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December 2013

From the first investigations involving cooling spheres of iron over 200 years ago, to exact measurements of isotopes in meteorites, the quest to fathom the age of the Earth has been a difficult path for generations of scientists. With a cast of characters as diverse as its many types of experiment, find out about geology’s finest hour.

> In a nUTsheLL

The age of The Earth

34 December 2013

Trial and errorIn 1938, the young American physicist Alfred Nier, working with a new mass spectrometer at Harvard University, tried to identify all the known isotopes of lead (chemical symbol Pb). As expected, he quickly saw the three known isotopes – 206Pb, 207Pb and 208Pb – but at the end of the spectrum a tiny blip was seen. The minute spectrum of primordial lead was finally visible and identified as 204Pb. The missing piece in the uranium-lead jigsaw had at last been found.

As the technology progressed, another American, Claire Patterson, succeeded in determining the vanishingly small amounts of lead in iron meteorites. Patterson spent the next three years trying to prove the relationship and in 1956, he demonstrated that the Earth, planets and meteorites had a common ancestry. Furthermore, samples from the Earth (and later, the Moon) also fell on that line. This proved that the Earth and the meteorites were formed at the same time from the same solar material around 4.5 billion years ago.

In 1910, Arthur Holmes set out to determine the uranium/lead (U/Pb) ratio of 17 different minerals in a rock, in order to both date the rock and prove that lead was the stable decay product of uranium.

He spent days separating the minerals from the rock, the resulting powder being ‘fused with borax in a

platinum crucible, and the resultant glass dissolved in dilute hydrochloric acid. After boiling and standing for several days in a corked flask [1], [radon] was boiled out, collected in a gas-holder [2], and ultimately transferred to an electroscope [3], which measured the amount of radon.

The known rate at which uranium decayed to radon gave the amount of uranium present. While waiting for the radon to accumulate, the lead was measured using delicate chemical techniques. In order to verify results, analysis of each mineral was repeated up to five times.

At one point Holmes discarded all the data and started again because radon leaked into the room, contaminating his results. He calculated the average U/Pb ratio from these minerals to be 0.045 and the rock to be 370 million years old.

Furthermore, the U/Pb ratio increased consistently with age, demonstrating the reliability of the uranium-lead dating method. This technique was eventually used to date the age of the Earth.

1) A solution of the dissolved mineral is boiled

2) Radon is collected here

3) The amount of radon present is measured with an electroscope

The apparatus used by Arthur Holmes to determine the ratio of uranium to lead in minerals. A mineral solution is boiled (1) and the resultant gas stored (2) before the amount of radon is measured by an electroscope (3)

Water condenser

To vacuum pump

The Key experImenT By MEASurinG THE rATiO OF urAniuM TO LEAD in rOcKS, ArTHur HOLMES FOunD A rELiABLE DATinG METHOD AnD PAVED THE WAy FOr THE AGE OF THE EArTH TO BE DETErMinED

of the 20th Century must have been thrilling. The excitement over the discovery of X-rays in 1895 and the realisation in 1896 that uranium emitted similar ‘mysterious rays’ (termed ‘radioactivity’ by Marie Curie), triggered an explosion of activity in labs around the world.

In 1897, JJ Thomson discovered the electron and in 1902 Ernest Rutherford and Frederick Soddy revealed radioactive decay. They astounded the world with their announcement that in the process of radioactive decay, one element changed into another: uranium decayed to radium, which in turn decayed to the gas radon.

Shortly afterwards, Soddy demonstrated that not only radon was produced, but helium as well, and that radon was also unstable and went on to decay to other elements.

rock of agesHaving identified that helium was a by-product of uranium decay, it was but a short step for Rutherford to realise that if the rate of helium production could be established, a relatively simple calculation would show how long it had taken for the helium to accumulate, and the age of the rock could be established. A year later, Rutherford

became the first person ever to date a rock by radioactive decay – obtaining an age of 40 Ma.

Unfortunately, there was a flaw in his method and it was Robert Strutt, a physics lecturer at the Royal College of Science in London, who recognised it: because helium is a gas, it can escape from the rock. In 1907, Bertram Boltwood, an American chemist, analysed rocks containing uranium and noticed that along with helium, large amounts of lead were present. He concluded that lead was indeed the final decay product of uranium and that a reliable technique had been found for dating rocks – it has been used ever since.

The oldest date in his dataset was 1,640 Ma, showing that the Earth must be at least that age. Progress was slow and the discovery of isotopes by Frederick Soddy in 1913 complicated things considerably. Furthermore, Arthur Holmes argued, some lead had probably been around since the Earth first formed – called primordial lead – but if he could not identify which isotope of lead was the result of the decay from uranium and which isotope was that of primordial lead, his dates would be inaccurate.

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Dr cherry Lewis is an honorary research Fellow in the School of Earth Sciences at the university of Bristol, uK.

1877-1956 1922-19951824-1907 1911-1994 1890-1965

G William Thomson, (Lord Kelvin) was a mathematician and physicist at the University of Glasgow. He regarded his work on the age of the Earth as his most important contribution to science.

G Alfred nier American physicist at Harvard University who pioneered the development of mass spectrometry. He discovered 204Pb and provided Arthur Holmes with data to calculate Earth’s age.

Frederick Soddy English chemist whose discoveries of radioactive decay (with Ernest Rutherford at McGill University) and isotopes at the University of Glasgow revolutionised the science of radioactivity.

G claire PattersonAmerican geochemist who finally dated the age of the Earth at the California Institute of Technology, by isolating microgram quantities of lead from meteorites. He later changed his first name to Clair.

Arthur Holmes English physicist and geologist who devel-oped the uranium-lead dating technique. Hol-mes worked at Durham University building the geological time scale.

THrEE HunDrED yEArS OF inVESTiGATinG THE PrOPErTiES OF ELEMEnTS HAS SHOWn uS HOW OLD EArTH iSTImeLIne

Following Alfred Nier’s discovery of a 2,480 million-year-old rock, Holmes uses Nier’s data to develop a model for calculating the Earth’s age, which he determines to be 3,015 million years old.

Count Buffon calculates the age of the Earth to be 74,832 years by heating spheres of iron and timing how long they took to cool, then scaling up his results to the size of the Earth.

Lord Kelvin determines that the Earth was a molten globe between 20 and 400 million years ago, but by 1899 had revised the time downwards to between 20 and 40 million years ago.

Ernest Rutherford and Frederick Soddy discover radioactive decay; two years later Rutherford dates the first rock determined by radioactive decay. It is found to be 40 million years old.

Arthur Holmes develops the uranium-lead dating technique and calculates the Earth must be at least 1,640 million years old. Two years later, Soddy discovers isotopes which greatly improve the accuracy of dating.

18621775 1902 1911 1946

THE SciEnTiSTS WHOSE EFFOrTS FOrGED A BriGHT FuTurE FOr GEOLOGyCasT of CharaCTers

Claire Patterson analyses the lead content of five meteorites and a sample from Earth, which defines the age of the Earth, Moon and meteorites to be 4,550 ± 70 Ma.

1956

HoW Do WE KNoW?

ncient Greek mathematician Euclid believed that sight occurs because the eye emits

light. Hero of Alexandria pronounced that light must travel at infinite speed as distant stars appear at the instant one’s eyes open. And in the 11th Century, the Basran mathematician Alhazen wrote his Book Of Optics, where he argued that light moves from object to eye, with a finite speed that varies depending on the medium through which it passes. Ideas continued to flow. In the 13th Century, Roger Bacon used the ideas of Alhazen to support the idea that light travels at a very high speed, faster than sound but finite.

As late as the 17th Century, luminaries such as Kepler and Descartes insisted that light travels infinitely fast. In 1629, the Dutch philosopher Isaac Beeckman proposed an experiment wherein the flash of a cannon was reflected by a mirror, about a mile away, and the time lapse measured. Galileo independently proposed a similar experiment, in 1667. No time delay was detected.

With our modern knowledge of light’s

Dutch mathematician Christiaan Huygens used this to estimate a speed for light of about 220,000km/s, about 70 per cent of the modern value.

The next step in the story again involves astronomy, and the aberration of light. Rain that is falling vertically when you are at rest appears to be falling from a point in front of you as you walk forwards – you have to tip your umbrella to keep dry. Walk in the opposite direction and the origin of the raindrops now also appears to be in the opposite direction. Now think of the falling rain as light travelling from a distant star, and your motion being that of the Earth through the heavens. The apparent position of a star varies during the year due to this phenomenon, known as aberration.

James Bradley, the Astronomer Royal, discovered this phenomenon in 1729. He deduced that light travels about 10,200 times faster than the Earth in its orbit, 295,000km/s, an estimate that is within about two per cent of the modern value.

Back down to Earth To determine high speed requires either

THe

speed, we know it would have taken about one hundred-thousandth of a second for it to make the round trip. That’s less than the reaction time of the observers, hence their inability to measure any delay – the distances involved were simply too small. By contrast, the distances between the planets are so large that light takes several minutes to travel between them.

In Paris, Giovanni Cassini had been observing the moons of Jupiter, which in their orbits disappear behind the planet and reappear later. His measurements varied, and he attributed this to light having a finite speed. Danish astronomer Ole Rømer joined Cassini, and in 1676 noticed that the time that Io, Jupiter’s innermost moon, takes to reappear is less when the Earth is approaching Jupiter than when it’s receding from it. This confirmed Cassini’s conjecture – when Earth is approaching Jupiter, it has moved nearer while the light is en route, and the total distance for the light to travel is less. Hence it arrives relatively early. Rømer’s measurements and his discovery of the correlation with Earth’s motion cause him to be credited with the discovery. In 1690,

SPeed of LIgHT

It’s the universal speed limit and the key to making sense of the Cosmos, but how did scientists discover how fast light can travel?

By PROf fRAnK cLOSE

a

36 December 2013

How do we know?

How fast light can travel is a question that scientific minds

have been grappling with since ancient Greece. Today we can

measure the speed of light very precisely but, as this article

explains, it took hundreds of years and lots of theories to get

to where we are now.

> In a nUTsheLL

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accessing a large distance, as in astronomy, or the ability to measure very small time intervals. The French physicist Louis Fizeau in 1849 found a way to do this on Earth. He shone light between the teeth of a rapidly rotating wheel. A mirror five miles away reflected the light back. He was able to infer the speed of light, some 313,000km/s. In 1862, Leon Foucault used a similar idea, and found a speed of 299,796km/s, which is remarkably close to the modern value of 299,792.46km/s.

In 1865 James Clerk Maxwell published his work on electromagnetic waves, in which light is a wave of electric and magnetic fields. In any electromagnetic wave, an electric field disappears and a magnetic field emerges, and vice versa, over and over. The resistance or ‘stiffness’ of free space to the former is called its electric permittivity, while its resistance to the magnetic field is called its magnetic permeability. In Maxwell’s theory, the speed of light is related to these quantities. The ease with which the electric and magnetic fields can oscillate back and forth determine the speed at which the electromagnetic wave travels. It turns out that the product of these quantities is proportional to the inverse of the square

of the speed of light. So in a sense Kepler was right,

centuries ago. If space offered no resistance – in Maxwell’s theory, if the electric or magnetic ‘stiffness’ were zero – the speed of light would indeed be infinite. But in reality, the electric and magnetic ‘stiffness’ are not zero, and when their values were inserted into Maxwell’s equations at the end of the 19th Century, they gave a value of 299,788km/s, then the most accurate estimate of the speed of light available.

Onwards to Einstein In 1887, Albert Michelson and Edward Morley in the USA attempted to measure the speed of the Earth through the ‘ether’ – a medium then believed to permeate all space – by measuring the difference in the speed of light in two perpendicular directions. Michelson and Morley’s setup proved highly sensitive and, to their surprise, demonstrated that the speed of light is universal, independent of direction. In turn, this led Einstein to insist that the ether does not exist (at least in the form then believed), and to propose his theory of Special Relativity in 1905. In particular, Einstein’s theory implies that the speed

of light in a vacuum is nature’s speed limit: no object that has mass can ever attain the speed of light in a vacuum, while any particles that have no mass must travel through a vacuum at this universal speed. However, light is slowed when it passes through a transparent medium, such as water or glass; it is possible for particles such as an electron to travel through the medium faster than light, but still below the absolute speed limit.

Today, advanced highly stable lasers, and the measurement of time intervals using atomic clocks, enable the most accurate value of 299,792,458m/s, with an uncertainty of just 1m/s.

Consequently, since 1983 it has been agreed to ‘fix’ the speed of light at the above value, and to define the metre so that there are exactly 299,792,458 of them in the distance that light travels in a vacuum in one second. So today, instead of measuring the speed of light relative to the space-time of the Universe, as physicists struggled to do for centuries, we determine the latter from the speed of light.

The Key experImenTHOW OBSErVinG THE MOVEMEnT OF THE MOOnS OF JuPiTEr PrOViDED 17TH cEnTury ASTrOnOMErS cASSini, røMEr AnD HuyGEnS WiTH An EArLy inDicATiOn OF THE SPEED OF LiGHT

Io, the innermost moon of Jupiter, orbits that planet every 42.5 hours. Viewed from Earth, Io periodically disappears behind Jupiter and reappears later. It was thought that the time between eclipses would be the same.

However, when Giovanni Cassini made measurements around the year 1671, the results kept changing. He had the insight that this could be due to light taking time to travel from Jupiter to Earth, during which period the Earth had moved. Therefore the distance travelled from Jupiter to Cassini’s telescope would vary from one eclipse to another, depending on whether the Earth was moving towards or away from Jupiter.

Strangely, Cassini seems not to have trusted his intuition, and his assistant, Ole Rømer, performed his own measurements. When these were combined with Cassini’s, Rømer realised that the variations correlated with the relative motion of Earth and Jupiter. He made a long series of measurements, which established this, and which led to an estimate of light’s speed to be over 220,000km/s. For many, this was so unimaginably fast as to be regarded as infinite, and Rømer’s ideas were not universally believed.

It was not until James Bradley measured the speed of light by means of stellar aberration that Rømer’s theory was accepted.

Frank close is a professor of Physics at the university of Oxford, uK and the author of The Infinity Puzzle.

The speed of light

Distance light travels

Distance light travels

Earth

Earth

Sun

Jupiter

Jupiter

Io

Io

In the top diagram, Earth is nearer to Jupiter in its orbit around the Sun. Later in the orbit, it’s closer (bottom). Light has less distance to travel, shortening the interval between eclipses of Io

Diagram not to scale

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December 2013

1564 –1642 1831-1879 964-1040 1644-1710 1819- 1868

G Alhazen based in Cairo, the Basra-born

mathematician wrote the seven-volume Book Of Optics

from 1011-1020. This was translated into Latin in the

12th Century, and influenced western thought regard-

ing the rainbow and optics in general. This inspired

Roger Bacon (1214-1294), an English philosopher who is often wrongly credited for

Alhazen’s ideas.

G Ole rømer during his time as assistant to Giovanni Cassini

(1625-1712) in Paris, the Danish astronomer observed the moons of

Jupiter. Although Cassini had the idea that the

data showed that light travels at finite speed,

it was Rømer who demonstrated this.

Galileo Galilei often regarded as the father of

modern science, the Italian polymath’s work led to the theory of mechanics. He

also made improvements to the telescope and founded

observational astronomy. He proposed that the planets

orbit the Sun, which is at the centre of the Solar System.

G James clerk Maxwell the Scotsman is credited

with uniting all known phenomena of electricity

and magnetism in a theory that predicted the existence of electromagnetic waves. The speed of these waves agreed with that of light.

This established light, radio waves, x-rays and more as all being electromagnetic

waves that differ in frequency and wavelength.

Leon Foucault in addition to his work on

the speed of light, including showing that it travels more slowly through water than

through air, the French physicist is known for the Foucault pendulum. This

offers a practical way of seeing the effects of

Earth’s rotation.

HOW SciEnTiSTS SPEnT 300 yEArS DEViSinG EVEr MOrE AccurATE WAyS OF MEASurinG THE SPEED OF LiGHTTImeLIne

After Ole Rømer shows that light travels at a finite speed, fellow Dane Christiaan Huygens calculates this speed to be around 220,000km/s.

French physicist Léon Foucault uses rotating mirrors to calculate the speed of light at 299,796km/s.

James Maxwell shows light to be an electromagnetic wave, enabling its speed to be calculated from known properties of space.

The concept that the speed of light is universal, independent of the speed of the source or of the observer, forms the basis of the Special Theory of Relativity developed by Albert Einstein.

18621690 1865 1905 1972

SOME OF THE GrEAT MinDS THAT POnDErED THE SPEED OF LiGHT THrOuGH THE AGESCasT of CharaCTers

1983

A laser (below) is used to measure the frequency of a particular spectral line of a krypton atom. By combining this information with the definition of the metre, the speed of light in a vacuum is measured to a precision of one part in a billion: 299,792,458m/s, to an accuracy of 1m/s.

Light speed made absolute at the 17th General Conference on Weights and Measures. As a result, a metre is now defined as 1/299,792,458th the distance travelled by light in a vacuum in one second.

From controversial beginnings to irrefutable evidence, it’s taken over 200 years to reveal earth’s Ice Ages

By JOHn GRIBBIn

F

eARTH'S

fRoZen PAST

HoW Do WE KNoW?

or hundreds of years, European people were aware of large lumps of rock, some as big as a house,

lying around in places where they didn’t belong, far from the strata where such material originated. They became known as erratic boulders, shortened to ‘erratics’, and until late in the 18th Century the accepted story was that they had been dumped by the great Biblical Flood.

But in 1787 a Swiss preacher, Bernard Kuhn, suggested that these boulders had been carried to their present locations by ice, not by water. In the 1790s the Scottish pioneer of geology, James Hutton, reached the same conclusion after a visit to the Jura Mountains of France and Switzerland. But the idea languished until it was taken up and vigorously promoted by another Swiss, Louis Agassiz, who was born in 1807.

Agassiz picked up the Ice Age idea from a geologist, Jean de Charpentier, who gave a talk on the topic in Lucerne at the 1834 meeting of the Swiss Society of Natural Sciences. He reported how heaps of rocky debris, known as moraines, are left behind by retreating glaciers, and speculated that the Swiss glaciers had once been joined

across the surface of that huge ocean of ice.’

Such language attracted attention, but in scientific terms a much more important event also occurred in 1840, when Agassiz presented his ideas to a meeting of the British Association for the Advancement of Science, held in Glasgow in September. The great geologist Charles Lyell, who was a big influence on Charles Darwin, was in the audience, and like many who heard the Ice Age theory for the first time, was unconvinced. But as a good scientist, soon after the meeting he headed into the Highlands to look for evidence in the form of ‘terminal moraines’ left behind by long-melted glaciers, and found them.

Before the year was out, the Ice Age theory had been presented to the Geological Society in London, endorsed by Lyell, and established as fact. But this raised more questions. When had the Ice Age occurred? And why?

The seeds of the modern theory of Ice Ages (note the plural) were sown in a book published in 1842. The author was Joseph Adhémar, a mathematician who worked in Paris, and his book was called

in a single ice sheet extending across the mountains and perhaps reaching into the nearby lowlands of Europe.

controversial findingsBy the time the next annual meeting of the Society came around, at Neuchâtel on 24 July 1837, Agassiz was its president. The audience settled into their seats expecting a dull presidential address on fossil fishes, and were astonished when he let rip with an impassioned lecture on the Ice Age, in which that very term was introduced (in German, as Eiszeit).

In 1840, Agassiz presented the evidence in a book, Étude Sur Les Glaciers, written in language that could not be ignored: ‘Europe, previously covered with tropical vegetation and inhabited by herds of great elephants, enormous hippopotami, and gigantic carnivora became suddenly buried under a vast expanse of ice covering plains, lakes, seas and plateaus alike. The silence of death followed… springs dried up, streams ceased to flow, and sunrays rising over that frozen shore… were met only by the whistling of northern winds and the rumbling of the crevasses as they opened

40 December 2013

> In a nUTsheLLFrom solving the mystery of giant boulders

left scattered across Europe, to intricate calculations describing the motion of the Earth around the Sun, it’s taken over 200

years for scientists to discover when and why Earth has periodic frozen epochs.

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42 December 2013

Earth’s Frozen Past

Révolutions De La Mer. It contained one golden nugget. This was the idea that the climate on Earth is modulated by changes in the orbit of our planet around the Sun.

Seasonal effects In the 17th Century, Johannes Kepler had realised that the orbit of our planet is slightly elliptical. So Northern Hemisphere summers are a tiny bit cooler than they would otherwise be, and Northern Hemisphere winters are a tiny bit warmer. But the cycle of the seasons itself is, of course, explained by the tilt of the Earth, which brings us short, cold winter days and long, hot summer days, completely overwhelming this small orbital effect. But Adhémar thought longer term.

Because the Earth travels more swiftly when it is nearer to the Sun, it spends seven days less traversing the (Northern Hemisphere) winter half of its orbit than it does traversing the summer half. In the south, winters are longer than summers. Adhémar argued that over thousands of years this extra length of winter had allowed the vast Antarctic ice sheet to grow. But he also knew that because of a wobble of the spinning Earth (like the wobble of a spinning top), the pattern of the seasons slowly shifts around the orbit

of the Earth as the millennia go by. Some 11,000 years ago, Northern winter was seven days longer than summer. And 11,000 years before that, the pattern was the same as today.

Voilà! An explanation of not one but many Ice Ages, alternating in the Northern and Southern Hemispheres. The only snag is, the idea was wrong. The actual amount of heat ‘lost’ during the seven extra days of winter is nowhere near enough to make great ice sheets grow. But it did set people thinking about the orbital influence on climate.

Enter James Croll, born in Scotland on 2 January 1821. Croll published his first paper on Ice Ages in 1864. He developed his ideas over many years, but the final version can be summed up simply. Croll suggested that when Northern Hemisphere winters were particularly cold, snow and ice would spread across the continents, making an Ice Age.

cold, hard mathsBy the end of the 19th Century, researchers tested Croll’s theories and showed that he was wrong.

Croll calculated that between 100,000 and 80,000 years ago the world should have been thawing out of an Ice Age. In

fact, the geological evidence showed that at that time it was plunging into an Ice Age. He had got it exactly backwards. And nobody had realised the significance – the implication that what you need to start an Ice Age is not cold winters, but cool summers. The person who made this clear was a Serbian mathematician, Milutin Milankovic.

It took Milankovic two years to come up with a model describing how the insolation had changed over the millennia for each band of latitudes on Earth. His results were published in 1920, and soon after reading them Wladimir Köppen, a Russian-born German meteorologist, realised that they showed how Ice Ages are associated with cool summers.

What we now know is that Ice Ages roughly 100,000 years long are separated by slightly warmer ‘interglacials’ about 10,000 years long, and that the present interglacial began about 10,000 years ago. If it were not for global warming, the next Ice Age would be just around the corner.

The key moment in the Ice Age story came in 1836, when de Charpentier took a skeptical Agassiz up into the Alps. Before then, Agassiz was firmly convinced that erratics were the result of rocks being left by a Biblical Flood. But in the best tradition of science, when confronted with evidence to the contrary he recanted. As the famous physicist Richard Feynman later said: “If it disagrees with experiment, then it is wrong.” This applies to observations as well as to experiments.

Agassiz spent several years studying erratics in the Alps, discovering that some boulders in the area came from as far afield as Scandinavia. This is what led him to the idea that a vast area of Europe had once been blanketed in a sheet of ice.

In 1840, history was repeated when the British geologist Charles Lyell set out to see the evidence for himself after hearing Agassiz speak about the Ice Age theory. Once again, he found irrefutable evidence for the previous existence of a great ice sheet, this time covering Scotland. It came in the form of scars, known as ‘parallel roads’, along the sides of the valley of Glen Roy, just south of the Great Glen. The ‘roads’ mark the shorelines of former lakes trapped in the valley by glacial dams.

Agassiz’s ‘Hôtel de Neuchâtelois’, which he built in the Swiss Alps around a huge boulder on a glacier during an expedition in 1840

The Key observaTIon A WALK TAKEn By TWO MEn in THE ALPS – OnE A SKEPTic, THE OTHEr EnTirELy cOnVincED OF HiS iDEAS – WAS THE DriVinG FOrcE BEHinD THE SciEncE THAT rEVEALED THE icE AGES

John Gribbin is a science writer and co-author of Ice Age (Allen Lane).

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1807-1873 1879-19581786-1855 1797-1875 1821-1890

G Jean de charpentier was a mining engineer, born in Germany as Johann von Charpentier. He adapted his name when he moved to Switzerland to take charge of the salt mines at Bex. His interest in geology led him to study the moraines scattered in the valleys there.

G charles Lyell was the pre-eminent geologist of his time. He promoted the ‘uniformitarian’ idea that the same processes we see today (volcanoes, earthquakes and so on) explain the changes that have occurred during Earth’s history. This implied a very long history, allowing time for evolution to work.

Louis Agassiz travelled to North America in 1846 to study the local geology and natural history and give a series of lectures. These were so successful that he was offered a permanent job, and stayed in the USA, where he was a major influence on the development of American science.

G Milutin Milankovic also calculated solar radiation data for Mercury, Venus, Mars and the Moon. He worked in civil engineering before taking up a post in Belgrade, where he returned after the War. In 1948 he became Vice President of the Serbian Academy of Sciences.

James croll worked as a carpenter in Glasgow, a travelling salesman, and proprietor of the only temperance hotel in a town with 16 hostelries selling alcohol. After his caretaking job, he became a full-time scientist, receiving honorary degrees, and was elected Fellow of the Royal Society in 1876.

iT TOOK OVEr 200 yEArS OF OBSErVATiOnS FOr GEOLOGiSTS TO rEVEAL THE TruTH ABOuT EArTH’S FrOzEn PASTTImeLIne

Milutin Milankovic calculates how the ‘insolation’ of the Earth at different latitudes has changed over thousands of years because of the effects discussed by Croll.

Bernard Kuhn unsuccessfully tries to convince geologists that erratics seen at low altitudes far down Swiss valleys had been dumped there by retreating glaciers, implying that the valleys were once full of ice.

Jean de Charpentier gives a talk to the Swiss Society of Natural Sciences on the idea that glaciers had once covered Switzerland, the Jura mountains and other parts of Europe. Louis Agassiz is in attendance.

Louis Agassiz (pictured) publishes a book dramatically expounding a much bigger vision of ice stretching from the North Pole to the Mediterranean. The same year he convinces British geologists including Charles Lyell that the theory is right.

James Croll publishes his first paper on climate change, the start of the development of his idea that very cold winters, produced by cyclical changes in the Earth’s tilt, are responsible for the onset of Ice Ages.

18341787 1840 1864 1916

THE SciEnTiSTS WHO PuT THEir HEADS ABOVE THE PArAPET TO PrOVE THAT icE AGES TOOK PLAcECasT of CharaCTers

hroughout the history of chemistry, the discovery of a new element has been regarded as an important

event and much credit has been granted to those who made such a find. Two major scientific breakthroughs then placed important constraints on the search for new elements, while still leaving plenty of scope for controversy.

The first of these major discoveries was the periodic table, that wonderful system of classification that serves to bring order to the elements while placing them into families of groups with similar properties. The periodic table was independently formulated by at least six scientists in different countries. The most famous of these was the Russian chemist, Dimitri Mendeleev, who in 1869 succeeded in accommodating the 63 elements that were known at the time into a coherent system.

In addition, Mendeleev had the audacity to predict the existence, and even the properties, of several new elements that would fill the empty spaces in his periodic table. His three best-known predictions were for elements that he called eka-boron, eka-aluminium and

after tellurium. As a result of such irregularities it was

not clear whether any more elements existed between, for example, hydrogen and helium.

This brings us to the second major discovery, which resolved most of the outstanding issues about missing elements. In 1913 an English physicist, Henry Moseley, found that a better means of ordering the elements was provided by an ordinal number derived from his experiments with X-ray spectra (see ‘The key experiment,’ pxx) that ran from 1 for hydrogen to 92 for uranium. Each element had its own ordinal number, that soon became known as its ‘atomic number’. Unlike the atomic weights for each element, there were no fractional values and so there were no longer any ambiguities.

At this point the hunt for missing elements became more focused and it became clear that precisely seven elements remained to be discovered between the original boundaries of the periodic table from elements 1 to 92. The missing elements had atomic numbers of 43, 61, 72, 75, 85, 87 and 91.

eka-silicon. Once discovered, they were given the names scandium, gallium and germanium respectively.

Weight problemsHere was the first signpost for how we know if elements are missing. If gaps were present in the periodic table, it meant that certain elements still awaited discovery. But things are not quite that simple, especially when dealing with the heavier elements.

The problem was that the periodic table originally ordered the elements according to their increasing atomic weights. But it turns out that subsequent elements in the table do not differ by a constant value of atomic weight. For example, the atomic weight of hydrogen is 1.008, that of the next element helium is 4.003 and the next element lithium has atoms with a weight of 6.941. There are even some ‘monster cases’ where two elements actually fall in the wrong order according to their atomic weights. For example, the element iodine has a lower atomic weight than tellurium and yet according to its chemical and physical properties it should appear

Once the periodic table had been discovered, the race was on among scientists to find the missing pieces in the puzzle…

By DR ERIc ScERRI

T

THe

MISSIngeLeMenTS

44 December 2013

HoW Do WE KNoW?

Elements are the building blocks of the natural world. The first periodic

table, a system describing all known elements, was produced in 1869,

revealing that a number were yet to be discovered – and scientific glory

awaited those who could isolate them.

> In a nUTsheLL

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First bloodThe first element to be bagged was actually the heaviest one, element 91, which was claimed by two teams of researchers before being credited to Lise Meitner and Otto Hahn in 1917, who were to achieve even greater fame when they discovered nuclear fission in 1938. Not surprisingly, in view of its close proximity to uranium in the periodic table, element 91 is also radioactive. It was decided that the new element should be called prot-actinium, an element that forms actinium (element 89) upon radioactive decay.

A few years earlier, the Polish radiochemist Kasimir Fajans had discovered a very short-lived isotope of this element that he named brevium but to his credit, was quick to relinquish his claim when he heard of Meitner and Hahn’s discovery of a different isotope with a half-life of about 32,500 years. This was due to a rule that maintained that the discovery of a new element should be assigned to whoever discovered the longest-lived isotope of an element.

The second element of the missing seven was element 72, which was named hafnium by its discoverers George de Hevesy from Hungary and Dirk Coster from Holland. This discovery was bitterly disputed however, especially by the French chemist Georges Urbain who thought he had discovered the element as early as 1911.

The third missing element was first claimed in 1908 by a Japanese chemist,

Masataka Ogawa, who was working at University College, London. His advisor William Ramsey, who had discovered a number of noble gas elements, suggested that they might name it nipponium. This element could not be produced again. To this day another Japanese chemist, Kenji Yoshihara, maintains that Ogawa had in fact discovered element 75, but discovery of the element now called rhenium is generally attributed to the husband and wife team of Ida and Walter Noddack, in 1925.

The fourth elementPerhaps the most controversial of all the missing seven elements to be discovered is the fourth. The element now called technetium was also first claimed by the Noddacks, who called it ‘masurium’, but nobody was able to reproduce their results. The official discovery of the element is attributed to two Italian scientists, Emilio Segrè and Carlo Perrier, a physicist and chemist respectively.

The fifth element also involved a good deal of controversy. A chemistry professor in Alabama, called Fred Allison claimed in 1930 that he had invented a new method for measuring what he called a magneto-optical effect, and that this had led him to discover not only element 87, but also element 85. The genuine element 87 was discovered in 1939 by a French woman, Marguerite Perey. She had been an assistant of Marie Curie in Paris. Perey named the element francium in honor of her homeland.

Emilio Segrè also synthesised the sixth element after relocating to the University of California, Berkeley, where he teamed up with Dale Corson and Kenneth MacKenzie. In 1949, they bombarded a sample of bismuth-209 with alpha particles to produce astatine-211. The final discovery in this ‘tale of seven elements’ involved an equally tortuous route. First there was a team of Italians that included Luigi Rolla and Lorenzo Fernández, who claimed to have detected some X-ray lines at just the frequencies expected for element 61. Next, a couple of teams in the US made independent claims for the element: Charles James and his co-workers believed they had recorded the X-ray lines of the element, as did Smith Hopkins at the University of Illinois. But none of this stood the test of time. Like technetium and astatine, element 61, promethium, had to be synthesised artificially. It was a task carried out in 1945 by Jacob Marinsky and Lawrence Glendenin by the irradiation of uranium in a graphite reactor.

Curiously perhaps, even before all the seven elements had been discovered, an element beyond uranium, neptunium, was produced. Since then a remarkable 26 elements have been artificially synthesised, up to and including element 118. But that’s another story…

The Key experImenT BOuncinG x-rAyS OFF DiFFErEnT TyPES OF METAL PrOViDED THE KEy TO A MOrE cOnSiSTEnT METHOD OF cLASSiFyinG THE ELEMEnTS - THEir ATOMic nuMBEr

Henry Moseley in the Balliol-Trinity laboratory at the university of Oxford, c. 1910

Henry Moseley’s key experiment, carried out a century ago in 1913, was based on the reflection of X-rays. It had been discovered that when X-rays strike a metal target, they emit secondary rays that are characteristic of the metal in question.

Moseley adapted this experiment so that he could change the target metal without having to dismantle the apparatus each time. The secondary rays from each metal were then reflected from a crystal and the image was recorded on a photographic plate. In this way, Moseley was able to measure the frequencies of the reflected X-rays and found a simple relationship between the square root of the frequency and an ordinal number to represent each metal.

The graph that Moseley obtained showed that in terms of its X-ray frequency, the metal cobalt came before nickel. This agreed with the chemical order of the elements and confirmed that Moseley’s ordinal number – or atomic number, as it soon became known – provided a better means to order the elements than their atomic weight.

Moseley’s initial experiments only considered a sequence of 10 elements, between calcium and zinc, but he soon expanded his study to most of the elements lying between aluminium and gold.

Dr Eric Scerri teaches chemistry at ucLA and is the author of A Tale Of Seven Elements. For more on his writing, see ericscerri.com.

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The missing Elements

1887-1915 1909-19751897-1907 1878-1968 1896-1978

G Dimitri Mendeleev was perhaps the most famous Russian scientist of any epoch. He discovered the periodic table of the ele-ments, which he first pub-lished in 1869. He arrived at his arrangement of the elements while in the process of writing a book on inorganic chemistry for students.

G Lise Meitner discovered the element protactinium as well as nuclear fission with Otto Hahn. Fission became the basis of nuclear weapons and nuclear power. An Austrian-born physicist, she was forced to flee Germany in 1936 because of her Jewish heritage, settling in Sweden and eventually the UK.

Henry Moseley published eight scientific articles during his lifetime. In one of these the English physicist found a simple relationship between the frequencies of reflected X-rays and an integral value for each element — its atomic number. He was tragically killed while fighting at the battle of Gallipoli in WWI.

G Marguerite Perey discovered francium, the last naturally occurring element. A French radiochemist, she began as a technician working with Marie Curie and made her key discovery before obtaining an undergraduate degree. She was the first woman to be elected to France’s Académie des Sciences.

ida noddack was a German chemist and physicist who was co-discoverer of the element rhenium along with her husband Walter Noddack. They also claimed to have discovered another element that they named masurium, but that turned out to be spurious.

MEnDELEEV’S 1869 PEriODic TABLE SPArKED A SciEnTiFic rAcE THAT WOuLD LAST FOr OVEr 100 yEArSTImeLIne

Marguerite Perey discovers the last naturally occurring element in Paris. There are only about 30g of this element, francium, in the whole of the Earth’s crust.

Mendeleev publishes the first of his periodic tables and uses it to correct some atomic weights and to correctly predict the existence of several previ-ously unknown elements.

Henry Moseley conducts the first of his two classic studies on the frequency of X-ray lines emitted from a se-quence of 10 elements, thereby establishing the experimental basis for the property of atomic number.

Lise Meitner and Otto Hahn discover the first of the seven ‘missing elements’ in the periodic table. The isotope of the element later called protactinium has a half-life of 32,500 years.

Emilio Segrè (pictured) and Carlo Perrier discover technetium, the first of the seven missing elements to be artificially created. Technetium would go on to find important applica-tions, such as in medicine.

19131869 1917 1937 1939

A rOLL-cALL OF SciEnTiSTS WHO DiScOVErED THE MiSSinG ELEMEnTSCasT of CharaCTers

Once scientists discovered that the continents were once joined together, the race began

to explain how they drifted apart

By DR cHERRy LEWIS

E

How THe

conTInenTS foRMed

HoW Do WE KNoW?

48

that Wegener’s mechanism to explain this was physically impossible. The British geologist, Arthur Holmes, was one of the few who favoured continental drift. In December 1927 he wrote a ground-breaking paper, postulating that differential heating of the Earth’s interior, generated by the decay of radioactive elements within it, caused convection in the substratum beneath the crust. Although the substratum appeared solid, Holmes believed that over vast periods of time it behaved like a very thick, hot liquid; as hot material reached the top of a convecting cell beneath a continent it would travel horizontally, producing a force that was sufficient to slowly drag the continents apart, allowing the substratum to rise into the gap and form new ocean floor. This convection, Holmes claimed, was the mechanism that drove continents around the globe.

underwater worldIn the 1950s, groups collecting magnetic data from the ocean floors found a surprise beneath the Pacific: a pattern of linear magnetic stripes on the ocean floor that mirrored each other either side of

determined to start looking for evidence to support it.

In 1912 he felt confident enough to give his first lecture on the subject, publishing The Origin Of The Continents And Oceans in 1915. The book stated that during the late Palaeozoic era (about 350 million years ago) all the continents had been grouped together in one vast supercontinent he called Pangaea. As Pangaea started to break up, the continents slowly drifted apart, eventually arriving at their current positions. Some of the most convincing evidence was the palaeontological data. Not only did the tropical flora of the coal measures demarcate the equator of Pangaea, but Glossopteris ferns of the Permian era, which grew in a polar climate, were shown to cluster around Pangaea’s South Pole. In both Britain and America, Wegener’s ideas were received with incredulity and disbelief.

Although most geologists saw the logic of Wegener’s arguments, there was one question that could not be answered. Just how did the continents move?

Geophysicists in particular complained

ver since maps were made, people have noticed how the east coast of the Americas looks like it once

fitted snugly into the west coast of Africa and Europe – it isn’t a perfect fit, but it’s good enough to make many wonder whether they had once been joined together. As early as 1596, Dutch map-maker Abraham Ortelius considered that the Americas had been ‘torn away from Europe and Africa… by earthquakes and floods’.

But it was Antonio Snider-Pellegrini who in 1858 first reconstructed the continents as they might have looked before the split.

The Earth movesAlfred Wegener was a German meteorologist who, in 1910, was working at Marburg University in Frankfurt. On Christmas, as he and his roommate poured over the latest edition of a colour atlas, a thought occurred to him: “Does not the east coast of South America fit the west coast of Africa as though they had been contiguous in the past?” Wegener was so inspired by this revelation that he

December 2013

> In a nUTsheLLToday, the concept that the

continents sit on moving plates – and that earthquakes and tsunamis are caused by those plates shifting – is common knowledge. But while

such ideas were first put forward in the 1500s, it wasn’t until the 1960s that the theory of continental drift

was conclusively proven. sc

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How The Continents Formed

50 December 2013

The Key experImenT A DATinG METHOD uSinG DEEP-SEA cOrE SAMPLES PrOVED THAT THE THEOry OF cOnTinEnTAL DriFT WAS cOrrEcT

the mid-ocean ridge with almost perfect symmetry.

Since the early 20th Century it had been recognised that when rocks such as basalt (lava) cooled from their molten state, the magnetic particles within them become ‘fossilised’, pointing in the direction of the Earth’s magnetic field. And it was not until the ’50s that people realised this was caused by the polarity of the Earth’s magnetic field periodically flipping over, such that the South Pole became the magnetic pole.

In 1962, Harry Hess, then Head of Geology at Princeton University, put forward a startling proposal. Seafloor spreading, as Hess’s theory became known, predicted that as ‘rising limbs of mantle-convection cells’ welled up from the depths beneath the mid-ocean ridges, the new material pushed the previous flow apart so that half would move to either side of the ridge, slightly widening the ocean each time. The two continents, once part of the same landmass, would be thousands of kilometres distant. Furthermore, instead of continents ploughing through oceanic crust as Wegener had proposed, Hess had them riding on a conveyor belt of convecting mantle.

Earth’s barcodeThe significance of the ocean floor’s magnetic stripes then dawned on two British geophysicists, Fred Vine and his PhD supervisor at Cambridge, Drummond Matthews. In 1963 they proposed that if spreading of the ocean floor occurred as Hess suggested, the stripes must represent the periodic ‘flipping’ of the Earth’s magnetic field, fossilised in basalts as they oozed out from the mid-ocean ridge.

In 1965, a new magnetic survey of the Juan de Fuca Ridge in the northeastern Pacific was made. It was immediately evident that the youngest rocks were nearest to the ridge, while the oldest were furthest away and adjacent to the continent. The following year, samples from deep sea cores from the Pacific showed that the timing and pattern of magnetic reversals in the core samples matched those determined from lava flows on land. This verified Vine’s work and the theory of continental drift at long last became indisputable.

Tectonics todayToday’s lithosphere is divided into eight large plates and many smaller ones. Their average rate of movement is about 4cm

a year – about the rate your fingernails grow. What’s still not entirely clear, however, is why some plates move faster than others.

The process generally starts with heating at the base of the continental crust, which causes it to become more plastic and less dense. Because less dense objects rise in relation to denser objects, the heated area becomes a broad dome. As the crust bows upward, fractures occur that gradually grow into rifts which start to break up the continent. Eventually basaltic material wells up between the continental fragments, pushing them further and further apart until an ocean such as the Atlantic forms.

By the end of the 1960s, a revolution had occurred in geology, comparable to that caused by Darwin a hundred years earlier in biology, when he proposed his theory of evolution. Today, the great unifying theory of plate tectonics, as continental drift is now called, explains just about every geological feature you care to imagine.

A method for dating certain rocks, known as potassium-argon dating, was pioneered in the 1950s, when geologists wanted to know how frequently magnetic reversals occurred. By the early 1960s, a geomagnetic reversal timescale was developed to allow Fred Vine to correlate onshore reversals with sea floor reversals and demonstrate that the ocean floors were youngest close to the ridge and oldest next to continents. It appeared to confirm Harry Hess’s theory of seafloor spreading and continental drift.

Verification of Vine’s work was provided by palaeomagnetic investigations of 650 samples from sediments in seven deep-sea cores taken from the Antarctic. Comparing the age and geomagnetic stratigraphy of the marine sediments with the onshore lavas provided an excellent correlation, thus linking the continents and oceans. The study also confirmed that at least 11 geomagnetic reversals had occurred over the last 3.5 million years. Vine used this enhanced timescale of reversals to predict the magnetic profile that would be expected across the central regions of mid-ocean ridges. By varying the estimated spreading rate, it was possible to obtain a very close simulation of all the observed anomalies and consequently determine the actual spreading rates at individual ridges. The theory of plate tectonics was born.

The process of potassium-argon

dating, as seen here, was crucial in helping

to prove theories of continental drift

Dr cherry Lewis is a geologist and the author of The Dating Game: One Man’s Search For The Age Of The Earth.

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1880-1930 b. 19391802–1885 1890-1965 1906-1969

G Antonio Snider-Pellegrini was an Italian-American

geographer who was the first to illustrate the continents as a single

landmass, citing fossils and matching rock

formations on opposing sides of the Atlantic to

support his ideas.

G Arthur Holmes proposed convection

currents in the mantle as a mechanism for driving continents around the

globe. But like Wegener, the British physicist’s ideas were ignored

for decades.

Alfred Wegener was the German meteorologist who first proposed the theory of

continental drift. He compiled a database to support his theory that the continents were slowly

drifting around the Earth and had once been joined in a

single landmass. He died on a polar expedition and did not live to see his theory revolutionise

the Earth sciences.

G Fred Vine proposed, along with Drummond Matthews (pictured to the right of Vine), that

magnetic stripes either side of mid-ocean ridges recorded the orientation of the Earth’s magnetic

field. He went on to provide evidence that

verified continental drift.

Harry Hess was a geologist at

Princeton University who suggested that the Earth’s

crust moved laterally away from volcanically

active mid-ocean ridges. His theory of seafloor

spreading made him one of the ‘founding fathers’ of

modern plate tectonics.

cOnTinEnTS MOVE OVEr THOuSAnDS OF yEArS – AnD iT TOOK uS nEArLy 400 TO FiGurE OuT HOW THE PrOcESS WOrKSTImeLIne

Mapping the ocean floor reveals vast mid-oceanic ridges that circumnavigate the globe, and a pattern of magnetic stripes that mirror each other either side of the ridges.

Harry Hess proposes ‘seafloor spreading’, whereby convection within the mantle brings molten material to the surface at mid-ocean ridges, slowly pushing the continents apart.

Abraham Ortelius suggests in print, having studied the first modern maps of the whole world, that the Americas had at some point in history been “torn away from Europe and Africa”.

Antonio Snider-Pellegrini depicts the continents as a single landmass on the first day of Creation, in a book entitled The Creation And Its Mysteries Unveiled.

Alfred Wegener proposes his theory of continental drift in which a single landmass, Pangaea, existed during the Carboniferous era. When Pangaea broke up, the fragments drifted slowly to their present positions.

Arthur Holmes suggests convection currents in the mantle as the mechanism for driving continents around the globe. Lack of a mechanism was hitherto a major obstacle preventing the acceptance of continental drift.

18581596 1912 1927 1950

THE SciEnTiSTS WHOSE EFFOrTS FOrGED A BriGHT FuTurE FOr GEOLOGyCasT of CharaCTers

1962

ome 400 years BC, in Ancient Greece, Democritus asserted that all material things are made from

tiny basic objects – atoms – that cannot be divided into smaller pieces. This was until Aristotle rejected atomic theory and the idea was ignored for nearly two millennia.

The Ancient Greeks also believed that everything was made from a few basic elements. Today we know that everything is made from chemical elements, such as hydrogen, carbon and oxygen. Today we also know that an atom is not the smallest thing: atoms are themselves divisible.

If you cut into an atom of any element, you will find its common constituents: lightweight, negatively charged electrons in the outer regions and a positively charged nucleus, dense and massive, at the centre. The only difference between the atom of one chemical element and another is the amount of electric charge on its nucleus, and the number of electrons that can be ensnared by the rule: ‘opposite charges attract’.

An atom of hydrogen, the lightest element, has a nucleus with one unit of charge, encircled by one electron.

had discovered that the weights of the various elements involved in chemical reactions were always in simple numerical proportions. The simplest example involved the gases, hydrogen and oxygen, combining to make water.

Careful measurements showed that if all of the gases were to be used and none left over, the weight of the oxygen would need to be eight times as much as that of hydrogen. As two hydrogen atoms and one oxygen atom have combined to make a molecule of water – H2

O – this implies that one oxygen atom must weigh eight times as much as two atoms of hydrogen. Relative to hydrogen, atoms of oxygen, carbon, calcium and iron weighed 16, 12, 40 and 56 times as much. This tantalising numerology was a hint that the atoms of the heavier elements having ‘more’ of the mystery material than the lighter ones. In other words: atoms are made of something even smaller.

With hindsight, by the middle of 19th Century two discoveries held the clue that atoms have an inner structure. First was the phenomenon of atomic

THe

STRUcTURe of THe AToM

Throughout history, we’ve endeavoured to find out what things are made of at the smallest scales of matter. Thanks to great scientists we now know the answer…

By PROf fRAnK cLOSE

s Helium, the next, has two, and the heaviest naturally occurring element, uranium, has 92. Obtaining this knowledge took scientists on a remarkable journey of discovery.

Atomic alchemyIn the 17th Century, Robert Boyle founded the atomic theory of matter; he was the first to recognise that substances are compounds of basic elements, and to propose that these elements are composed of basic particles: atoms. Boyle’s ideas were descriptive only. Quantitative chemistry came about in the late 18th Century when Antoine Lavoisier showed that the masses of individual elements stay the same – are ‘conserved’ – during chemical reactions. This led to the idea that basic elements were rearranging themselves in such processes.

Mass effectIn early 19th Century England, John Dalton suggested that all atoms in a given chemical element are exactly alike: the atoms of different elements being distinguished by their mass. He

HoW Do WE KNoW?

52 December 2013

> In a nUTsheLLFrom the first philosophical

forays into the make-up of matter in Ancient Greece to the 20th

Century’s exploration of quantum theory, find out about the pioneering physicists and the ground-breaking

experiments that have shown us the workings of the atom. s

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The Key experImenT in HiS MAncHESTEr LABOrATOry, THE PHySiciST ErnEST ruTHErFOrD AnD HiS cOLLEAGuES FOunD A WAy TO PrOBE THE HEArT OF An ATOM

Early in the 20th Century, Ernest Rutherford noticed that thin sheets of mica could deflect alpha particles (see ‘Need to know’ p101), which were moving at 15,000km/s. This could only have happened if they felt electric and magnetic forces far greater than anything known. He mused that these forces might be present within atoms.

Rutherford suggested that his colleague, Ernest Marsden, look to see if any alpha particles were deflected through very large angles. Instead of mica, Marsden used gold leaf that was only a few hundred atoms thick, and a scintillating screen to detect the scattered alpha particles. To everyone’s amazement he discovered that about one in 20,000 alphas were turned back in their tracks. Rutherford famously exclaimed: “It was as though you had fired a 15-inch shell at a piece of tissue paper and it had bounced back and hit you”.

Rutherford realised that the positive charge in an atom is concentrated in a massive and exceedingly compact central ‘nucleus’, and that it was the repulsion of like charges that was deflecting the relatively lightweight alpha (the nucleus of a gold atom being some 50 times more massive than an alpha particle).

The size of the nucleus relative to an atom was famously compared to being like a “fly in a cathedral”.

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spectra - when light emitted by hot elements was split into component colours, characteristic sets of lines showed up, like an atomic barcode unique to each element. Second, Dmitri Mendeleev discovered that when he listed the atomic elements in order of their atomic weights, elements having similar chemical properties periodically reoccurred. His celebrated Periodic Table Of The Elements contained gaps, which led him to predict that further elements must exist to fill them. In addition to spectra, and the periodic table, radioactivity showed that one element could transform spontaneously into another by emitting particles, a process known as transmutation. This raised two questions: what were the constituent parts of atoms and how were they arranged?

Answers came in 1897, when JJ Thomson found that electric current is carried by negatively charged particles: electrons. American Robert Millikan measured the electric charge of the electron and it led to two inferences: as electrons are so light, there must be other more massive particles in there too. And as atoms have no overall electric charge, the massive particles must be positively charged in order to neutralise the electrons’ negativity.

Scintillating screen

Large deflection

Radioactive source

Gold foil

Beam deflected

Beam of alpha particles

Beam transmitted with little or no

deflection

Science is goldenWhen Ernest Rutherford and his assistants Hans Geiger and Ernest Marsden bombarded atoms of gold with alpha particles – massive, positively charged particles emitted in radioactivity – they found that most of them passed through, but occasionally one would recoil violently (see ‘Key experiment’, p99). In 1911, Rutherford deduced that the gold atom must be mostly empty space, but with a dense central region, capable of deflecting the alpha particles. He called this the nucleus.

When Rutherford’s discovery of the positively charged atomic nucleus and Thomson’s discovery of the lightweight, negatively charged electron were married with the rule that opposite electrical charges attract, a seductively simple picture emerged of the atom as a miniature Solar System.

Quantum leapBut something was missing. It was the discovery of quantum theory: very small things, such as atoms, follow different laws from those of Newton, which explain the behaviour of objects that are large enough to see. Instead of an electron being able to go anywhere in an atom, it is limited, like someone on a ladder who can step only on

individual rungs. Danish physicist Niels Bohr articulated the idea in the summer of 1912. When an electron drops from a rung with high energy to one that is lower down, the excess energy is carried away by a photon of light. Conversely, if an atom is hit by a photon whose energy matches the gap between two rungs, the atom absorbs that photon, lifting the electron up the ladder.

Quantum theory goes one step further to explaining where electrons can be around a nucleus. Any particle can take on a wave-like character. What is familiar for electromagnetic waves occurs for electrons too. A single wave corresponds to the lowest rung of the energy ladder; two waves puts the electron on the second rung and so on.

The energies of the various waves are unique to atoms of a given element. The spectral lines that result when electrons jump from one rung to another are therefore like a barcode, identifying the elements present in the Sun and other stars. So although we can’t directly ‘see’ the electron waves within atoms, this hypothesis describes a host of historical phenomena and has led to a wealth of technological applications.

Frank close is a professor of Physics at the university of Oxford, uK and the author of The Infinity Puzzle.

54 December 2013

The structure of The atom

1834-1907 1885-1962 1766-1844 1856-1940 1871-1937

G John Dalton an English chemist and founder of

modern atomic theory. Born in Cumberland, he moved to Manchester where he taught mathematics and

natural philosophy. He stud-ied the behaviour of gases, and the atmosphere, but his most famous insights were with the atomic theory of chemistry, with which his

name is associated.

G Joseph (JJ) Thomson born in Manchester, he joined Trinity College,

Cambridge, in 1876. He spent the rest of his life there, becoming Master

in 1918. His work on the properties of gases

and atomic structure led to his discovery of the

electron, in 1897, and a Nobel Prize in 1906.

Dmitri Mendeleeva Russian chemist, most

famous for his Periodic Table Of The Elements, which he discovered while writing a textbook on chemistry in

1869. He was twice nomi-nated for the Nobel Prize, in 1906 and 1907, but this was rejected after claims that his

discovery was too old.

G niels Bohr a Danish physicist who made

major contributions to the foundations of quantum mechanics and to the

theory of atomic structure. His planetary model was

the forerunner of the modern picture of the atom. He won the Nobel Prize for

physics in 1922.

Ernest rutherfordthe New Zealand-born

British physicist is famous for discovering the atomic

nucleus, identifying forms of radioactivity, and fathering the field of nuclear physics.

Although he is best known for his discovery of the nuclear atom, his 1908 Nobel Prize was for chemistry and his

discovery of transmutation of the elements.

iT HAS TAKEn TWO cEnTuriES FOr SOME OF THE GrEATEST PHySiciSTS TO GET TO THE HEArT OF THE ATOMic WOrLDTImeLIne

John Dalton proposes that all matter is made of indestructible atoms; that atoms of different elements are distin-guished by their weights, and that chemical reac-tions occur when atoms are rearranged.

Joseph John (‘JJ’) Thomson (pictured) discovers the electron, and identifies it as a constituent of all atomic elements. It is negatively charged, which suggests that there must also exist positively charged constituents to neutralise the atom.

Ernest Rutherford discov-ers the positively charged atomic nucleus following experiments by Hans Gei-ger and Ernest Marsden. He realises the nucleus is massive and compact, and that an atom is mostly empty space.

Niels Bohr creates a conceptual picture of the atom like a miniature Solar System, where ‘planetary’ electrons orbit a central nuclear ‘Sun’.

18971803 1911 1913 1925

THE PiOnEErS THAT HAVE PEELED BAcK THE LAyErS OF THE ATOMic OniOn CasT of CharaCTers

1932

Erwin Schrödinger produces a quantum theory of electron behav-iour in the hydrogen atom in 1925. In 1928, Paul Dirac completes the theory, making it consistent with the theory of Special Relativity.

Atomic nucleus established to consist of protons and neutrons. The proton and neutron are today known to be made of more funda-mental seeds: quarks. The electron still appears to be indivisible.

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SciEncEnATurE

Por t folio

Andrew’s fascination with gannets culminated in three months camping alongside them at the northernmost tip of the Shetland Islands. His daily commute involved a 90m abseil down sheer cliffs, then a tortuous traverse along their rapidly eroding base to reach the heart of the gannets’ colony.

Matt and Richard set themselves the challenge of taking underwater images of gannets in the seas off Shetland, near Richard’s home. The coast here is picturesque but exposed, the weather unpredictable; despite attempts spanning several weeks, only a few days of photography were successful.

Photographs by Andrew Parkinson, Richard Shucksmith and Matt Doggett

the PrivAte liFe oF gAnnetS

THE CAlM SEMBlANCE Britain’ largest seabird, the gannet’s body and wings are white, with black on the outer wings. The head has a yellowish tinge and the bill is strong and spear-shaped. Gannets live for much of the year at sea, arriving at their breeding grounds between February and April and leaving in September.

TEENAGE CHICKSThe transition of a gannet from chick to subadult, here depicted over a period

of eight or nine weeks, sees a dramatic shift in character. As their down is blown away they become like human teenagers: noisy, aggressive and demanding – and frequently sporting ridiculous hairstyles!

Then, on the threshold of adulthood, a preoccupation with flight seems to

distract them, though this is perhaps the most dangerous time: the waters below are littered with the carcasses of those

that leapt too soon. Only when their dark juvenile plumage has been replaced by

feathers of a silvery hue, as in the final picture, are they truly ready

to take flight. AP

59December 2013

nATurEPORTFOLIO

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DIVING TESTThe gannet’s athletic hunting technique is

a spectacle to behold – and a test of skill to which the bird is supremely well adapted. Flying

directly into a headwind, the gannet will wing-brake and stall, up to 15m above the surface; peering down, its binocular vision fixed on a

mackerel below, it makes minute adjustments to its wings, tilting slightly to move incrementally

left or right. Then, with a final glance, it turns sharply and lets gravity take over. The bird folds its wings tighter and tighter until, at the point of impact with the water, it becomes arrow-like in

shape, reaching 100kph. AP

60 October 2013

SWEET AND TENDER HOOlIGANS

In contrast with their aggressive responses to intruding neighbours, the gannets’ exquisite, elaborate courtship rituals are the epitome of tenderness. I watched this pair

one May morning, fascinated by the varied moves in their

romantic repertoire: head bowing, allopreening, sky pointing and billing (shown) are just a few of the ways in which a couple communicates with

each other, reinforcing a pair bond that can last a lifetime. AP

DEEP IMPACT G Dozens of gannets circled above our boat, watching as we tossed mackerel over the side. When a single bird took the plunge, the others followed suit, with 20, 30, 40 birds diving around us. Gannets have evolved adaptations for this foraging method: air sacs in their head and neck inflate to minimise impact injuries, and they do not have external nostrils, so water is prevented from surging into the sinuses. Once in the ocean, we could hear the birds hitting the surface above our heads. A collision could have been dangerous for both bird and photographer – but as they were aiming for the fish so accurately, we never felt at risk. RS

SINK AND SWIM E

A gannet’s plunge-dive carries it only a few metres below the surface, but it is an adept swimmer, using both wings and feet to pursue fish to depths of approximately 30m. Two dive types have been described: V-shaped, shallower and lasting only a few seconds, and the more successful U-shaped dive, during which the bird may be submerged for about 20 seconds. Despite their large size, gannets are often victims of kleptoparasitism – we watched several above the water being harassed by skuas until they regurgitated their meals. MD

nATurEPORTFOLIO

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61December 2013

THE PHOTOGRAPHERS Andrew Parkinson is one of Britain’s foremost wildlife and nature photographers, and among BBC Wildlife Magazine’s most prolific contributors.

Richard Shucksmith and Matt Doggett have taken wildlife images together since university. They now form half of the Earth in Focus group.

FInD oUT moRE

Enjoy more of Matt and Richard’s amazing photographs of the underwater acrobatics of Shetland’s gannets at our website: E www.discoverwildlife.comE www.andrewparkinson.comE www.earthinfocus.com

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THE BIG FOOD FIGHTGannets often swallow prey underwater – to maximise consumption on each dive, to prevent other gannets from stealing their food and to avoid mugging by skuas or gulls at the surface. But there are other threats to the gannet’s food supply. Healthy stocks of mackerel – a favoured prey – are imperilled by a dispute between Scotland, Norway, Iceland and the Faroe Islands over fishing quotas, and potential overfishing would be a massive problem. Intelligent long-term management of fish stocks would go some way to securing the future of these magnificent hunters. RS

PORTFOLIOnATurE

62 December 2013

From printing DNA to buildings that heal themselves, science’s biggest names predict the most influential

discoveries of 2013

BReakthROUghs Of

2013

SciEncE

e’re getting better at manipulating materials at the nanoscale – creating tools from individual atoms and

molecules. As a result, nanotechnology is being used in things like LED lighting, silicon and plasma technology. But we’re going to see it applied to whole buildings.

There’s a lot of interest in harvesting the energy from the Sun in big structures. If you can get every building to act as a solar collector, you’ve solved the global energy problem. There are already solar cell paints. At the University of Notre Dame, they have a solar paint that uses semiconducting nanoparticles to produce energy.

At Oxford, Cambridge and Cornell universities, they have developed semiconductors whose molecules self-organise into the optimal shape to collect light and transmit the resulting electrical charge. In their so-called ‘gyroid-structure’ solar cells, the semiconductors incorporate molecules that are hydrophilic and others that are hydrophobic – water-loving and water-hating respectively. These molecules want to pull apart, but the molecular links between them prevent this. So instead, they spontaneously form a 3D structure that is good for light collection and conversion to an electrical current.

The fact that the semiconductor forms the optimal structure spontaneously means it

could be applied to large areas – including whole buildings. The big challenge now is to figure out how you cover a building with loads of wires so you can use that absorbed energy. The answer isn’t going to be people wiring up buildings with tiny wires. It’s going to be conductive material that will self-organise into wires, a vein structure, and collect energy from the paint.

But the use of nanomaterials in architecture won’t just be about energy capture. Buildings will also sense things and self-heal as part of what they are. After all, the reason we are so responsive – that we feel pain and heat – is that we have functional ‘nanotechnology’ in our cells. Evolution has optimised our cells to be able to detect things like heat and pain or if

Professor of Materials and Society at University College London, UK

marK mIodoWnIK

bUILdIngs ThaT heaL ThemseLves

Dr Henry Snaith peers through a

prototype solar cell

One of the self-assembling solar cells being developed at Oxford University

“Buildings will sense things and self-heal. that’s where

architecture is heading”

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64 December 2013

sTem CeLL organ TranspLanTs“I suspect that we will soon see one of the first liver or kidney transplants where the organ has been grown from the patient’s own cells. So the organ is artificial – there is no donor.

We’ve already had trachea transplants with tracheas grown from a patient’s own stem cells. But complicated organs are going to be harder.

The most significant breakthrough has been in the development of a scaffold material in which the cells can replicate and grow into a kidney, liver or eventually, perhaps, a heart. Once the organ has developed, the scaffold ‘dissolves’.

This field of research really couldn’t be any more exciting, because it solves so many problems.”

there’s a crack in your skin. That’s where architecture is heading.

At the moment buildings are static: they are built and have to be repaired. If you’re lucky they will automatically open and close a window. But in future, all the structures around us will be more responsive to the environment.

In this respect, we are working on a project where we’re trying to make large objects touch-sensitive. So it’s not just the screen of your mobile phone – it’s your whole room.

Dr Henry Snaith at Oxford University is at

the forefront of efforts to make buildings harness

power from the Sun

vIveK goyaL

gesTUre-ConTroLLed mobILe phones

You could soon be interact-

ing with your mobile device without even

touching it

InCreasIngLy poWerfUL ULTrasoUnd “There’s a lot going on in ultrasound imaging research at the moment. Like in our 3D work and many forms of computational imaging, ultrasound is being revolutionised by improvements in data processing. It’s also one of the medical imaging methods that tends to be extremely low cost. X-rays are not particu-larly cheap and can have long-term effects. And while MRI is non-ionising, and so doesn’t damage cells, an MRI machine is a huge piece of extremely expensive equipment. Ultrasound can be cheap and what people can get out of ultrasound seems to be improving rapidly these days.”

m very excited about the integration of 3D movement recognition systems into mobile devices. I think

it’s going to be a big thing in electronics that will take off soon.

Microsoft Kinect has transformed gaming because people are now used to using 3D gestural interfaces in computer games. Games are one use of these interfaces, but there’s potential elsewhere too – including with mobile phones and tablets. Kinect is much larger than a phone and uses a lot of power, so a big challenge is scaling the system down for a mobile device. You want to make the sensors as efficient as possible and advances are being made. But there are also big gains to be made in how you process the data – and that’s where my research group is involved.

Let’s say your goal is to build a gestural interface, then what you are looking to gather is information about where the user’s

hands are. There will be other things in the field of view, such as walls. But you are not looking to form a full image of the whole field of view. Once you reduce what you are interested in, then the mathematical modelling and processing allows you to get away with measuring less. We’ve built prototypes that demonstrate this.

People don’t mind adopting new interfaces – a few years ago there were no touchscreens on phones. So consumers are willing to change. But one thing that isn’t going to change is that you can’t see through your fingers. On a phone, you’re obscuring a significant proportion of your screen with them. So if you can do the same kinds of things with gestures as you do on a touchscreen – such as pinch to zoom – that’s already a nice development. And once you can move your hands in three dimensions instead of two, then new ideas for different kinds of interface will come along.

Principal Research Scientist in the Research Laboratory of Electronics at Massachusetts Institute of Technology, USA

i’

65December 2013

SciEncE BREAKTHROUGHS OF 2013

e’ve been looking at converting DNA into the 1s and 0s of computer code and sending that information as a

digital magnetic wave or an email around the Earth in less than a second. We’re also building what we are calling a digital-biological converter that will take that digital information and convert it back into functioning biology.

“You’ll be able to have a box next to your computer – the converter – and download insulin or a vaccine. With the H1N1 influenza virus, it took about nine months for the world to get a vaccine. In the US, 250,000 young people died in that interval. In the future, if there are lots of boxes around the world, it could be the end of pandemics. It’s the start of being able to get biology over the internet.

The first part of the process is encoding DNA for a vaccine or insulin in digital form. So we read the sequence of ACTG [adenine, cytosine, thymine and guanine – the molecules whose sequence encodes the information in DNA] in the genetic material and convert that into the 1s and 0s on a computer. That information is then sent to the digital-biological converter. Inside the converter there are four bottles of chemicals and the genetic material is printed.

Using this DNA, we can make proteins. No cells are required – you can just make a

American biologist and entrepreneur who created the first synthetic species

CraIg venTer

TransmITTIng LIfe aT LIghT speed andrea seLLa

sUper-effICIenT arTIfICIaL phoTosynThesIs

Professor of Inorganic Chemistry at University College London, UK

hotosynthesis is incredibly inefficient. For most plants, the percentage of the incoming light

energy which is actually transformed into sugar is around 1 per cent. So the challenge is on to beat those percentages – to make, say, hydrogen with 20 per cent efficiency. There’s a lot of hype around hydrogen – it releases enormous amounts of energy when it reacts with oxygen, so it can be used in fuel cells to power anything from cars and buses, to ships and submarines.

There’s been remarkable progress here, so significant developments are likely over the next 12 months. A couple of years ago, Daniel Nocera at MIT revealed the artificial leaf. This is a very clever device where a silicon photocell is coated so that, when dipped into water and exposed to sunlight,

hydrogen comes off one side, and oxygen the other. There was huge excitement when it was announced, but when they started looking at its scale-up costs and efficiency, the numbers just didn’t add up. To solve this, people are now working on each of the three main steps involved in simulating photosynthesis. First, you’ve got to capture the light – this causes a negatively charged electron to be excited. Second, you have to separate positive and negative charges. Then, you have to harness these charges to do the water-splitting chemistry.

Our need for fuels far outstrips what sunlight can deliver through photosynthesis. So a system that’s much more efficient would be a game-changer, because you could use sunlight and water to make meaningful amounts of fuel.

beTTer hydrogen sTorage“Just imagine something that is a teaspoon in size and yet is so holey and porous on the inside that you’d need a football field’s worth of wallpaper to cover it. These materials are known as ‘metal-organic frameworks’ (MOFs). In effect they’re molecular sponges, and scientists are now targeting MOFs with cavities that are suited for particular molecules. An MOF with holes that are of a very similar size and shape to the hydrogen molecule, and with the right sorts of intermolecular forces, can provide a way of storing hydrogen. Every week, there are peo-ple out there who are reporting MOFs with new structures and new shapes. It’s hoped that someone will soon find one that’s capable of storing fuel in the form of hydrogen gas with an energy density rivalling that of liquid hydrogen.”

P

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Daniel Nocera of Massachusetts Institute of Technology, holding his artificial leaf

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SciEncE BREAKTHROUGHS OF 2013

dose of insulin from a biological reaction. Or, rather than producing a protein, we can simply convert the DNA sequence into an RNA vaccine and for DNA vaccines, all you have to do is synthesise the DNA.

The first practical use will be in sending vaccine information to large centres around the world that are equipped to make large doses of vaccine. The next step will be each government having its own ability to do that [print vaccines] and then eventually it will go to hospitals and corporations. A lot of regula-tory hurdles will need to be overcome if people are going to do this in their own homes because it represents a fundamental change in how information is distributed and how information gets converted into meaningful things.

Anyone who has seen the movie Contagion would not want to see that played out around the globe. If we can prevent that, what a phe-nomenal contribution that would be.

I think standard manufacturing is moving towards distributed production using 3D printers. We are now making the first 3D biological printers.

It will not just change how we deal with pandemics, but also how we think of biology and life.

fUrTher dIsCoverIes aboUT

oUr personaL eCosysTem“The microbiome [all the microbes that live on, and in, the human body] is going to become more and more important for human medicine. We will see a big scale-up in what can be done in terms of measuring the microbiome. There’s an increasing number of clear links between the microbiome and diseases. Our skin has a significant number of different environments: we have different microbes in different areas of our skin, such as the mouth and the vagina. All of these are being studied around the world. And, particularly with some gastrointestinal diseases, there are very strong correlations.”

“I think standard manufacturing is moving towards

distributed production using

3D printers. We are now

making the first 3D biological printers”

Craig Venter is working on a similar device to Organovo’s Bioprinter that can print vaccines

Sent via email, a vaccine would be printed from organic chemicals

This 3D printer developed by Organovo can take

human cells and shape them into tissue

67December 2013

cientists are coming round to the idea that it’s possible that quantum mechanics – strange mechanisms

that work at the level of atoms and molecules – could play a role in mutations in DNA. So there’s a lot of people working to try and un-derstand its role in cancer. It’s a big leap to say we’re going to use quantum mechanics to help us cure cancer, but understanding its contribu-tion could lead to new technologies that could help us prevent and fight the disease.

What’s so exciting here is that we didn’t expect to find these mechanisms influencing biology. Quantum phenomena are delicate things, and the more complicated the system is, the harder it is for that quantum strange-ness to have an effect. It was thought that molecules inside a living cell were just far too complex, too messy, for the delicate quantum shenanigans to play a role.

In fact, it looks like life is the only system in the whole Universe where you can get a macroscopic, measurable effect because of the action of a single molecule. In normal, inanimate matter you’d never have a single

molecule being able to influence something made up of trillions and trillions of particles. But there’s something special about life that means it can.

You can think of mutations as just a hydrogen bond breaking somewhere and forming some-where else in DNA. So at our lab, we wondered whether it could just be a proton quantum jumping from one spot to another, creating a much bigger effect. So now we’re growing the

Professor of Physics at the University of Surrey, UK

JIm aL-KhaLILI

QUanTUm TooLs for sTUdyIng CanCer

bacterium E coli in the lab to observe its mutations.

The E coli is grown in deuterated water – heavy water. Gradually, its DNA will be made up of deuterium bonds, rather than hydrogen bonds, because the E coli will utilise what’s in its surroundings as it replicates and grows. If quantum tunnelling is indeed creating these mutations then the E coli cultured in deuterium would exhibit far fewer mutations, since deu-terium bonds are much heavier than hydrogen and are therefore far less likely to quantum jump. And, tentatively, this is what it looks like is happening.

It’s an ongoing study that’s still at the very early stages. You could turn around and say maybe the enzymes that make the DNA mutate are less efficient in heavy water. In other words, the results we’re getting could be down to something other than quantum effects. And that’s something we’d need to investigate as well.

But the fact that you can do these experi-ments now suggests that we can make serious progress. It’s something of an adventure.

“scientists are coming round

to the idea that quantum

mechanics could play a role in

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graphene-based nanoTeChnoLogy

“A lot of funding is going into research on the properties of graphene, and especially into how it can be used in nanotechnology. Progress in nanotech was already speeding along, but the discovery of graphene has accelerated matters. This is because it’s good at creating nanotubes, which are the building blocks of the nano-world. Certainly its properties suggest that it could soon enable the development of tiny ‘robots’ at the nanoscale. Graphene seems to be completely inert too, so it’s perfectly suited for medical applications.

A lot of researchers working in this area are now submitting research grants involving graphene, because that’s where masses of funding is coming from. Even chemists are getting in on the action because graphene appears to be almost impermeable to anything but water, so it could prove incredibly useful as a membrane for separating materials. This would enable us to get at the precious elements we’re after.”

sheILa nIrenberg

CraCKIng The braIn’s Code To repaIr damage

Nirenberg’s system replaces the retina with an en-coder that transmits an image to the brain

Jim Al-Khalili is working on an experiment looking at the effects of quantum

mechanics on our cells

neW avenUes for aLzheImer’s researCh“There’s potentially some exciting things happening with research into Alzheimer’s disease at the

moment. The conventional wisdom has been that what initiates the dementia happens to all brain areas at approximately the same time. Different areas of the brain may show Alzheimer’s at differ-ent times, but they have all been targeted at the same time. In the same way that if you sneeze on a bunch of people, they may all get sick, but not at the same time.

However, there was a finding in April 2012 that when a person gets Alzheimer’s they get demen-tia in one area, then another area, then another area. And there is a possibility that if it’s a disease that spreads from one area to another, it could dramatically change how you treat it. If you can figure out a way to stop the spread, you can contain it.”

ptogenetics is an exciting area. There are light-sensitive proteins in algae, bacteria and fungi, the genes for

which can be expressed in cells in the brain. When you shine a light on those cells, they pro-duce an electrical signal. It allows you to make brain cells behave according to your control.

Others have been using this to drive neu-rones to fire, but the trouble is the brain uses its own code. It speaks a language like Morse code, but far more complicated. We figured out the code transmitted by the retina and we can make the optic nerve – the output neurones of the retina – send the normal coded signal to the brain. It’s a treatment for complete blind-ness, where someone has a damaged retina with no photoreceptors. You can give them a device that sits in a pair of glasses and takes

images. It translates images into the brain’s code as light pulses, so the optic nerve sends the right signal to the brain.

If you bring optogenetics together with the brain’s code, remarkable things are possible. For instance, you could jump over dead sensory cells used in hearing or an area damaged by a stroke to make sure the brain receives the signal.

The code takes the form of equations. If you give someone a visual input and record the output of the neurones, you get equations that describe the relationship between input and output. Those equations are the code-book. If you put any visual stimulus through the equations, out comes the answer. It could work elsewhere in the body – determining the code of the auditory nerve, for example.

Neuroscientist and principal investigator in the Nirenberg Lab at Cornell University in the US

Encoder Transducer

Image Retina Brain

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69December 2013

SciEncE BREAKTHROUGHS OF 2013

milestonesthat changed

6th Century BC

The first purported form of democracy is practiced in Athens, Greece, where community leaders are selected from a poll ballot open to all citizens.

King John signs the Magna Carta ushering a democratic system in England and the English Parliament is created. The Charter limits the political influence of the royal family and increases the power of the people. 1689

In England, The Bill of Rights lays down the limits on the powers of the sovereign and sets out the rights of Parliament, rules for freedom of speech, the requirement to regular elections and the right to petition.

1215

democracy

The wheel is introduced as a mode for transportation of goods, in Mesopotamia, Indus Valley, the Northen Caucasus and central Europe.

4500-3300 BC

6500-4500 BC

The first wheel to make an appearance is the potters wheel – a disk with a hole cut in the middle. The oldest wheel was found in Solvenia in 2002, estimated to be 5100 – 5350-years-old.

2200-1550 BC

In India, the spoked wheel and the chariot are made. The spoke introduces a new subtlety since it’s loaded in tension, not compression, which sets precedent for the early mode of transportation.

wheel

In China, money in the shape of small knives or spades made of bronze is used as currency along with bronze replicas of cowrie’s shells. This replaces the barter system.

The Chinese use bronzed Wen coins with holes, and the Indians use punched disks as currency. The Lydians create staters coins from electrum.

During the Tang Dynasty in China, paper money, known as jiaozi, is introduced alongside coins.

700-500 BC

money1000 BC 7th Century

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the worldMoshita Prajapati traces the origins of the foremost inventions

that have shaped and built the world as we know it

Thomas Jefferson’s Declaration of Independence, allows America to become the first country to break away from rule of the monarch and become an independent democracy. 1832

Prime Minister of Britain, Charles Grey, introduces the Great Reform Act transferring voting privileges from the nobles and the gentry to the population living in towns, boroughs and underdeveloped industrial towns.

Women are allowed to vote in the United States of America and in the United Kingdom in the year 1918.

1776 1913

2013

India is the largest democracy practicing in the world.

Used as gears in devices, such as clocks, water wheels, cogwheels, and astrolabes for sailors to navigate. 1906

Harvey Samuel Firestone’s Firestone and Tire Company begins the mass production of tyres for automobiles owing to a deal with Henry Ford of Ford Company.

The new age Tweel wheel from Michelin is a radical shock absorbing rubber tread band that distributes pressure on dozens of flexible polyurethane spokes, supported by an aluminum centre.

15th Century 2013

In 1661, Stockholms Banco (bank), issues the first banknotes in Europe. It has to be noted that in 1664 the bank ran out of coins to redeem notes and ceased operating in the same year.

1950

Physical currency is supplemented with plastic money; the Credit Card. Diners Club issues the first card in USA.

In October, Standford Federal Credit Union becomes the first financial institution to offer online banking services.

17th Century

1994 Sweden considers implementing digital currency and withdrawing coins and paper currency from its market.

2012

HiSTOry

The British Industrial Revolution (1760-1840) was due to coming together of a series of technical developments primarily in the fields of manufacturing textile, harnessing steam power and the iron industry. The invention of the Flying Shuttle by John Kay (1733) greatly increased the speed of weaving, which led to an increase in demand for yarn, leading to the inventions of the Spinning Jenny by James Hargreaves (1764),

industrial revolution

telephone

The Advanced Research Projects Agency Networks (ARPANET) goes online, linking four US universities. The network is designed to provide a communication network linking the country in case of a nuclear attack or war.

1969

internet

1831

Michael Faraday shows that the vibrations on metal objects could be transformed to electrical signals.

1861

German scientist and inventor, Johann Philip Reis constructs a machine, which changes sounds to electrical signals and then back to sound once again.

1965

Two computers at MIT are made to communicate with each other over a shared network.

1971

Ray Tomlinson, a programmer, sends the first email over ARPANET. To achieve this, he uses the @ to distinguish between the sender’s name and network name in the email address.

5th Century

The concept of zero takes shape in India and is represented by words, such as shunya (void), kha (sky), akasa (space), bindu (dot). Brahmagupta gives zero its exalted status in mathematics.

Bhaskara I gives zero its symbol ‘0’.

7th Century

zero

Sir Tim Berners-Lee, invents the World Wide Web (WWW), and starts work on a global Hypertext Transfer Protocol system (HTTP) a year later. 1991

The world’s first website (info.cern.ch) is set up. And on 30 April 1993, CERN, makes the World Wide Web available as a free software for public use.

There are 634 million active websites on the Internet and 2.4 billion people are accessing the Internet on a regular basis.

1989

2012

and the water powered Water Frame by Richard Arkwright (1769). James Watt in 1775 improved upon Newcomen’s steam engine design, which leads to advances in the designs and functioning of locomotives, steamboats, and cotton mills. In the year 1709, Abraham Darby I, devises a method to produce pig iron in a blast furnace by using coke, heralding the production of iron as a raw material, which fuels construction of railway tracks and machines.

1876

On 10 March, Alexander Graham Bell successfully transmits a speech, “Mr. Watson, come here! I want to see you!” through his version of the modern telephone.

During the management of Bell Company employee Theodore Vail, 10,000 phones come into mass use.

1878

1973

Motorola employee, Dr Martin Cooper, invents the cellular mobile phone. The handset, built in 90 days, is called the DynaTAC 8000x.

There are over 6.8 billion mobile users in the world.

2013

The Google search engine unveils its presence, changing the rules of engagement with the Internet.

1998

8th Century

Zero reaches the Arab world. Mohammed ibn-Musa al-Khowarizmi begins his work on complex algebraic equations.

Mohammed ibn-Musa al-Khowarizmi’s works reach England and Europe, where Fibbonnaci further expands its function, especially into accounting and taxes.

Newton and Leibniz created rules for working with zero, leading to innovations and discoveries in physics, engineering, calculus, economics finance, etc.

12th Century 16th Century

HiSTOry

X X X X

From a ruler that can measure the width of an atom to the clock that’s accurate to one-642,121,496,772,646th of a second,

michael Banks investigates the world’s ultimate precision instruments

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This optical atomic clock at the National Physical

Laboratory in Middlesex ‘ticks’ 9,192,631,770

times a second

THE ULTIMATE CLoCKit’s time for the next generation of super-accurate atomic timepieces

magine a clock so accurate that if it had been switched on when the Universe was born 13.7 billion years ago it would

only have lost one second by today. That is what the latest gold-standard timepieces, called optical atomic clocks, will soon be able to achieve.

In today’s atomic clocks – the world’s official timekeepers – charged atoms, or ions, float in a ‘trap’ and are held in place by electromagnetic fields. They are then subjected to a beam of light that causes electrons in the ions to jump from a lower to a higher energy state. This jumping

takes place at a regular rate and acts as the atomic clock’s ‘tick’. The higher the frequency of the ticks, the more accurately time intervals can be measured. The UK’s official time is currently measured at the National Physical Laboratory (NPL) in Middlesex using caesium-133 atoms, whose electrons jump an incredible 9,192,631,770 times a second.

But physicists are currently looking at a number of different atoms that would allow the clock to ‘tick’ even more frequently. At NPL, scientists are putting ytterbium ions – already used in

On 30 June 2012, a ‘leap

second’ was added to the official time measured by atomic

clocks to account for the fact that the Earth’s rotation had slowed a little. This meant that solar time

– determined by our planet’s rotation – was in danger of getting out of sync with the

official time

portable X-ray machines – through their paces, zapping them with lasers in ion traps. The signs are good. Research published in 2012 by NPL showed that a ytterbium ion clock would tick 642,121,496,772,646 times per second – a tick rate nearly five orders of magnitude higher than caesium. “Optical clocks are set to become the ultimate in timekeeping,” says Professor Patrick Gill at NPL.

Satellite navigation uses atomic clocks, so more capable timepieces would make these systems even more accurate. Their sensitivity to outside influences could also be put to good use. For instance, portable optical clocks could be used to search for natural resources. As they are moved around, their tick rate would vary slightly in response to small changes in Earth’s gravity, which could be caused by variations in rock porosity – a key way to find oil.

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THE ULTIMATE WeIghIng sCaLesA balance that’s 5,000,000 times more accurate than your bathroom scales

n a vault at the International Bureau of Weights and Measures in Sèvres, France, is a cylinder of platinum-iridium

alloy. This lump of metal, known as Le Grand K, is the official kilogram – its weight defines 1kg and it’s used to calibrate scales around the world. The trouble is, its weight is changing relative to identical cylinders of the alloy kept at other sites around the world – which is not what a fixed standard is supposed to do. No-one is sure why. One theory is the gradual release of gas from the cylinder, which was forged in the 1880s.

So now the idea is to define the kilogram in terms of truly fundamental constants whose value was fixed at the birth of the Universe, and remain constant throughout space and time. Measure the speed of light in a vacuum, for example, and it’s always the same.

This watt balance, based at Canada’s National Research Council, determines the weight of a kilogram by measuring it against the strength of an electric current

That’s the aim of the watt balance: an incredibly sensitive weighing machine that will fix the amount of mass we call the kilogram in terms of fundamental constants that govern the Universe. The idea behind the watt balance is simple enough. Put the kilogram mass in one pan of a pair of scales, and then measure the force needed in the other pan to restore balance. By using high-precision electromagnetic coils to apply the balancing force, the kilogram can then be defined in terms of a force whose value is fixed for all time.

But the devil is in the details. For a start, weight is not the same as mass: it’s the product of mass and the local strength of gravity. So precise measurements of the strength of gravity have to be carried out to calculate the mass. Worse still, the electromagnetic force varies in complex ways

sTrange

bUT TrUe The watt balance is so sensitive to magnetic fields it can sense when trains leave a station a

few kilometres away and is even susceptible to the wind blowing

trees and lifting the ground slightly. These effects have to

be compensated for during the experiment

inside the watt balance, and has to be measured using delicate quantum effects. But an ingenious set of measurements that cancels out these problems has been devised. From a formula, it spits out the mass of the kilogram, linking it to the fundamental constant governing the quantum effects used to measure it, known as the Planck constant.

Watt balances like the one at the National Research Council (NRC) in Canada are expected to pin down the kilogram with mind-boggling precision – to the nearest 0.00000002kg. In contrast, your weighing scales are probably only accurate to the nearest 0.1kg. “Using the Planck constant will give us a clear realisation of mass without depending on a lump of metal that is constantly changing weight,” says Dr Dave Inglis, watt balance project leader at the NRC.

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THE ULTIMATE ThermomeTerHow the speed of jiggling atoms will define temperatures in the future

o the naked eye it looks perfect in shape – a sphere of copper so smooth that any irregularities on its surface can only be

seen under a microscope. It is just one part of a delicate experiment that is likely to lead to an overhaul in how temperature is measured, allowing readings to be accurate even at extremely high and extremely low temperatures.

Since 1954, temperature has been defined rather inelegantly in terms of the triple-point of water – a mixture of pressure and temperature where H2O exists as a liquid, gas and solid. This triple point is actually 273.16K on the Kelvin scale or 0.01oC. The lowest possible temperature is 0K, or absolute

zero. So Kelvin is a simple scale based on these two points. But at extremes in temperature – millions of kelvin, and close to absolute zero – this system breaks down because it is, after all, just a crude scale. That’s a problem if you want to measure, say, the temperature of a nuclear explosion.

So the hot topic in temperature research is determining something called the Boltzmann constant. This relates the amount that atoms or molecules jiggle around in a liquid or gas – the amount of kinetic energy they contain, in other words – with temperature. Knowing the Boltzmann constant would mean that by measuring atoms jiggling in something, you would be measuring its

temperature directly and accurately. We currently have estimates of the constant, but physicists need to come up with a highly accurate figure they can rely on for it to form the central part of temperature measurement.

At the National Physical Laboratory in Middlesex they’ve been trying to do just that by measuring the molecular speed of argon gas at a given temperature. They’re doing this by firing sound waves into a copper sphere containing the gas and performing calculations that reveal the molecular speed from the frequency of the sound that emerges. The perfection of the sphere is vital for these calculations, allowing the exact volume of gas to be measured.

The triple point of water – the basis for temperature

readings – is measured using a blend of distilled ocean water. This

is because different forms, or isotopes, of oxygen and hydrogen

are present in varying amounts in the world’s oceans. Having an official water mix ensures that 0oc is the

same all over the planet

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The National Physical Laboratory is studying the speed of mol-ecules of argon gas in this copper sphere, to help pin down the Boltzmann constant

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The Laser interferometer

Gravitational Wave Observatory in the uS is

currently the world’s most accurate ruler. it is so sensitive it can detect a change in length

the size of your thumb on something on the scale of the

entire Milky Way

sTrange bUT TrUe

F YOU WANT to produce precise blades for jet engines or highly accurate medical equipment, you would use laser

interferometry – a technique that enables eye-wateringly accurate distance measurements. But a new method is likely to become ruler of the world: atom interferometry.

In laser interferometry, a beam of light is split into two halves. One beam reflects off a mirror into a detector, while the other shines through the object that needs to be measured before it reflects off a second mirror and into the detector. Because the path one beam travels is fixed while the other beam travels an extra distance – through the object – the two light beams interfere when they meet in the detector. It’s the pattern of this interference that reveals the size of the object.

Atom interferometry uses the same principle – two beams travel different paths before meeting in a detector, their interference revealing the size of an object. But here it’s the same atoms that make up the two beams that are detected, something made possible by quantum phenomena – the strange behaviour of matter at the level of subatomic particles.

Atoms can be made to act like waves if cooled to near absolute zero – something that can be achieved by firing a laser at them. Firing other lasers at these atoms also puts them in a superposition of states where they are in two different places at the same time, flying along different trajectories. If the route an atom takes along one of the paths varies from the other by as little as one picometre – or one trillionth of a metre – thanks to an object being in the way, this can be detected.

Physicists at NASA’s Goddard Space Flight Center and Stanford University in the US are currently developing an atom interferometer in which lasers are fired at rubidium atoms to create measuring beams. The team believes that it will be capable of detecting gravitational waves produced when massive objects, such as stars, disrupt the fabric of space-time – making objects move by miniscule amounts.

The NASA/Stanford team envisions three spacecraft flying in a triangle formation, each equipped with an atom interferometer. If a gravitational wave rolled past, the interferometers would measure the miniscule movement of one craft in relation to another.

THE ULTIMATE rULerA mind-bending phenomenon will allow measurements accurate to a trillionth of a metre

Dr Michael Banks is the news editor of the uK based, Physics World magazine.

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SciEncE MEASUREMENT OF ALL THINGS

leaders, thinkers, risk-takers - moshita Prajapati lists indians that shaped modern india

changersgame

Kailash Sankhala was India’s first crusader who raised concerns

about the near extinction of the Bengal

Tiger in 1956. His research uncovered that the dwindling population was a result of extensive

hunting and poaching, and it led to the

foundation of Project Tiger, the world’s largest

wildlife conservation effort in 1973.

In 1974, Dr Bindeshwar Pathak, introduced

Sulabh Shauchalaya, the ‘pay and use’ toilet and bathing facilities for the

public. His dream was that this basic amenity

should be available to all Indian citizens. The

organisation has built over 1.2 million toilets

across the country.

On 14 March 1931, the movie Alam Ara directed

by Ardeshir Irani heralded the culture of

elaborate song and dance sequences in

Indian cinema. The film with its repertoire of seven songs set the

precedent for films with songs. Microphones

were hidden around the sets and songs were recorded on set with

musicians playing their instruments.

On 24 July 1991, P.V. Narsimha Rao put an

end to the License Raj era by allowing 51% of

Foreign Direct Investment in India.

Although under pressure from the IMF, this move

along with deregulation, privatisation and tax

reforms ushered in the liberalisation of Indian

economy. Rao came to be known as the Father

of Indian Economic Reforms.

P. V. Narsimha Rao

Kailash Sankhala

Bindeshwar Pathak

Ardeshir Irani

Lalit Modi

Under Jawaharlal Nehru’s directive in

1946, the All India Council of Technical

Education committee chaired by Sir N R

Sarkar, set up the first Indian Institute of

Technology (IIT) in Kharagpur, West Bengal in May 1950. Today, they are Institutes of National Importance, responsible

for enriching fields of science and engineering.

80 December 2013

Jehangir Ratanji Dadabhoy Tata in 1932, set up Tata Airlines, the first Indian

commercial carrier to transport mail and passengers

within India; it flew 1,60,000 miles, carrying 155

passengers and more than 10 tonnes of mail. In 1946, Tata

Airlines became Air India, the flag carrier of India, with

Indian Airlines catering to domestic route and Air India

to international routes.

Aruna Roy, founder and head of the Mazdoor Kisan Shakti

Sangathana is one of the early proponents of the Right To

Information Act, through her National Campaign for

People’s Right to Information in 1996. In 2002, H D Shourie’s

Freedom of Information Act was passed, but only in state

levels. In 2005, the Right To Information Act was passed,

applicable to all States and Union Territories in India

except the States of Jammu & Kashmir.

Raman Roy is considered as the pioneer of the Business Process Outsourcing (BPO)

industry in the country. In 1991, he set up the first lot of BPOs for American Express

and later for General Electric in Gurgaon, Delhi. According to reports, the IT-BPO sector

alone was expected to add 2,30,000 jobs in 2012, thus

providing direct employment to about 2.8 million.

Lalit Modi in 2008 unleashed the global phenomenon of the

Indian Premier League (IPL), based around the Twenty20 cricket format. By bringing

Bollywood personalities, business honchos and MNCs

onto the cricket field, the franchise during his three-year tenure as commissioner of the

IPL, was valued at $4 billion. Spinoffs of the IPL are found in Pakistan, South Africa, Sri

Lanka etc.

J. R. D. TataRaman

Roy

Lalit Modi

Lalit Modi

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Dr B. R. Ambedkar, left his legacy in the form of the

Constitution declaring India to be a sovereign, socialist,

secular, democratic republic, assuring its citizens of justice,

equality, and liberty, and endeavors to promote

fraternity among them. In 1948, he began revising the

Hindu Code Bill; to grant equal rights to women and to

re-organise the framework of the Hindu society by granting

women equal rights.

Following China’s successful nuclear test in 1967, Indira Gandhi pushed to develop

India’s nuclear power and on 18 May 1974, in Pokhran,

Rajasthan, India tested its first nuclear bomb, Pokhran I

(Smiling Buddha). In 1998, Atal Bihari Vajpayee, citing security

issues with Pakistan, commissioned Pokhran II

(Operation Shakti). On 11-13 May 1998, five nuclear bombs

were successfully tested in the same area.

Sam Pitroda, is considered as the father of India’s

telecommunications revolution. He ushered in an

era of accessible telecommunications that

included not only ISD and STD services, but also setting up the first PCOs in the country.

He also set up Videsh Sanchar Nigam Limited (VSNL) and

Mahanagar Telephone Nigam Limited (MTNL).

In 1971, Sanjay Gandhi as the Managing Director of Maruti

Limited, set out to create India’s first people’s car. In

1980, the company was revised as Maruti Udyog

Limited and in 1983, in collaboration with Japanese

automobile company Suzuki, the first Maruti 800 rolled off

the production line at a cost of `52,500.

Dr B. R. AmbedkarSam

Pitroda

Sanjay Gandhi

82 December 2013

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HiSTOry GAME CHANGERS

students across india from schools (grades 9-12) and colleges are participating in a contest organised in association with bbc knowledge to create appealing, innovative educational videos on any topic from their syllabus. winners will receive an award and their videos will be showcased at learnshift india 2013 – mumbai chapter.

to know more, visit www.learnshiftindia.com

LearnShift India 2013mumbai chapter will bring together a dynamic community of innovators and experts from diverse fields to demonstrate experiments, share insights and experiences, and work together to strengthen initiatives to address certain key school education challenges.

www.learnshiftindia.com

www.facebook.com/LearnShiftIndia

www.twitter.com/LearnShift (@learnshift)

Connect

simon Breakspear, Education Innovation Expert

avnita Bir, Principal, R.N. Podar School

The Curators

In aSSocIatIon wIth

lsi young change agent award

promotional feature

in this excerpt, ravana’s desire to appear no less than a god to his own people, marks his rise as the conquerer

of heaven and hell

inside the pages

This excerpt is published with permission from Campfire Graphic Novels (Kalyani Navyug Media Private Limited). No part of this excerpt maybe quoted or reproduced without prior consent from Campfire Graphic Novels (Kalyani Navyug Media Private Limited). Ravana-Roar of the Demon King by Abhimanyu Singh Sisodia (Campfire `195)

E

AN EXCERPT FROM A BOOK YOU SHOULD READ HiSTOry

E

AN EXCERPT FROM A BOOK YOU SHOULD READ HiSTOry

This excerpt is published from Ravana-Roar of the Demon King by Abhimanyu Singh Sisodia (Campfire `195)

ExPlORINg lIFE’S gREAT MYSTERIES

BY DAvID NORMAN INVESTIGATES

the Big idea

88 December 2013

wHAT kIllED THE DINOSAURS? The amazing story of how we’ve come to learn the fate of our reptilian predecessors

T hey came. They ruled. They died. Considering that the end of the dinosaurs took place millions of

years ago, it is remarkable how much we’ve learnt about their demise. To appreciate where our knowledge has come from, we need to delve into the fascinating history of palaeontology – the study of fossils.

In 1796 Cuvier published detailed descriptions of fossil elephant remains (those of mammoths and the American mastodon), which he compared with the bones and teeth of living elephants. He revealed that some fossils belonged to animals that were no longer alive: they were extinct. At the end of the paper, he wrote: “All of these facts, consistent among themselves, and not opposed by any report, seem to me to prove the existence of a world previous to ours, destroyed by some kind of catastrophe.”

Over the following years, Cuvier developed his ‘catastrophist’ interpretation of the history of Earth. He studied the geology of the Paris Basin and saw that it comprised a succession of sedimentary layers. Each layer contained its own recognisable fossils (its fauna), but Cuvier noticed that each fauna was replaced abruptly following a catastrophe, such as being submerged by floodwater.

He also described a variety of newly discovered and strange fossil reptiles, including pterosaurs (p89) (winged reptiles) and mosasaurs (p89) (gigantic marine lizards) and this led him to speculate about an ‘Age of Reptiles’, a time when reptiles dominated Earth, rather than the mammals that do so today.

Cuvier’s insights inspired a new era of fossil hunting. Over the first three decades of the 19th Century, several English collectors and geologists made some spectacular discoveries. Mary Anning from Lyme Regis in Dorset 12

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A fossilised plesiosaur discovered by Mary Anning at Lyme Regis, now held in the Natural History Museum

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discovered ichthyosaurs E(dolphin-shaped giant swimming reptiles), plesiosaurs (large, turtle-flippered and long-necked, swimming reptiles) and the partial skeleton of a pterosaur.

This new fossil evidence proved Cuvier’s hunch correct. There was a time in Earth’s history (referred to then as the ‘Secondary Era’ – now it is the Mesozoic Era) when the world was largely populated by gigantic land and sea-going reptiles. These remarkable new discoveries provoked very wide interest both scientifically and publicly. In Britain at this time a young, ambitious, medically-trained scientist called Richard Owen became keenly interested in Cuvier’s work. In 1840 and 1842 he published detailed reports through the newly founded British Association for the Advancement of Science (BAAS).

The second of Owen’s reports is particularly famous because it was here that he coined the term ‘Dinosaur’. In what was at the time a masterpiece of rational argument and anatomical insight, he drew on Cuvier’s intuitions and demonstrated that during the ‘Secondary Era’ there were some remarkable extinct animals that represented the zenith of reptilian organisation. These were the enaliosaurs (gigantic reptiles of the oceans that filled the ecological niches occupied today

Others, following Matthew’s line of thought, put the replacement of dinosaurs by mammals down to gradual cooling, gradual heating, coincident changes in the floras or, in more extreme examples, to the effects of environmental temperature on the sex of developing young within

ExPlORINg lIFE’S gREAT MYSTERIESthe Big idea

by whales and dolphins), the pterosaurs (reptilian equivalents of birds and bats today) and the dinosaurs (huge land-living animals that corresponded to the elephants, rhinos and hippos).

While the first half of the 19th century was dominated, intellectually, by Cuvier and his ‘catastrophist’ thinking, the latter half was marked by the ‘uniformitarianism’ advocated by the geologist Charles Lyell and the strongly allied theory of evolution by Natural Selection proposed by Charles Darwin. It was a non-catastrophic view that disasters did occur and extinctions were indisputable, but this did not greatly affect the gradual process of change.

Extinction eventsWith increasing data it became obvious that Cuvier’s catastrophes were real and not the by-product of missing data as Lyell and Darwin had suggested. Various explanations concerning these major punctuations in the history of life were bandied around. These included biblical views, such as the idea that extinction events were pre-ordained.

Palaeontologists began to speculate about mass extinctions more openly. Given the controversy that surrounded Darwinism at this time, some adopted a range of non-Darwinian models to explain extinction events.

Racial senility was one such concept. This saw life as a ladder-like succession of types, each new form better than the last. Dinosaurs, for example, represented a Mesozoic form of reptilian life that was replaced in younger rocks by ‘superior’ types of animal such as mammals. This view was supported by the observation that the anatomy of dinosaurs became increasingly ‘bizarre’ through time, manifested by the development of outlandish spines, horns and frills, as well as the loss of teeth, suggesting that the race had become old and, in effect ‘senile’.

In the 1920s, American vertebrate palaeontologist William Diller Matthew brought a fresh approach to the debate by focusing it on environmental change.

Mosasaur

Pterosaur

Ichthyosaur

He was struck by what he saw as a global change from wet swampy conditions (that appeared to favour dinosaurs) to drier and more arid conditions (that favoured mammals) across the Cretaceous-Palaeogene (K-Pg) boundary. This boundary marks the end of the Mesozoic era and the beginning of the Cenozoic era around 65 million years ago. He linked this change to the Laramide orogeny – episodes of mountain building and continental uplift that straddled the K-Pg boundary.

90 December 2013

ExPlORINg lIFE’S gREAT MYSTERIESthe Big idea

E

1 AsteroidA small rocky or metallic body in orbit around

the Sun. Most occur in the asteroid belt between the orbits of Mars and Jupiter, although other families exist, such as the near-Earth asteroids, which pose a collision danger with Earth.

2 deccan trapsOne of the largest volcanic features on Earth

formed 60-68 million years ago. They consist of multiple layers of solidified lava that are more than 2km thick and cover an area of 500,000km2 in west-central India.

3 iridiumAn element derived from micrometeorite dust

that falls to Earth at a constant and predictable rate. It is found in much higher levels in asteroids than on the surface of Earth.

4 K-Pg extinctionThe Cretaceous-Palaeogene extinction

event, also known as the Cretaceous-Tertiary (K-T) extinction event, occurred approximately 65.5 million years ago. It was a large-scale mass extinction of animal and plant species in a geologically short period of time.

5 PalaeontologyThe study of prehistoric life through fossils.

Palaeontological observations date back to the 5th Century, but the science became established in the 18th Century as a result of Georges Cuvier’s work on comparative anatomy, and developed rapidly in the 19th Century.

need To KnoW Key terms to understand how the dinosaurs were wiped out

of France (and may have been up to three times as large in the past). The massive outpouring of volcanic material occurred during a narrow interval of time across the K-Pg boundary.

Speculations about a link between the Deccan Traps and the dinosaur extinction began in the early 1970s. However, it was not until 1981 that Vincent Courtillot, Gerta Keller and other proponents of the volcanism model began to gather data. Early modelling focused on the gases released by the huge volcanic eruptions and how this might have led to a sudden cooling of Earth and mass extinction.

In terms of the data available, the asteroid theory appears to be the more robust. The flood-volcanism theory does not adequately explain the impact signature. Courtillot and Keller now seem to accept that an asteroid impact (or indeed several) occurred, but claim that these were merely a contributing factor to the extinction event.

eggs. Temperature dependent sex determination is known today in some egg-laying reptiles and it was argued that if temperatures did change significantly then all the hatchling dinosaurs would have been the same sex and their demise unavoidable!

From the 1960s onwards Robert Sloan and Leigh Van Valen became the most persistent and high-profile advocates of the environmental change model for dinosaur extinction. They argued that mammals replaced dinosaurs gradually across the K-Pg interval over a period of about 7

million years and that this change was brought about by climatic deterioration triggered by worldwide sea-level regression.

But, in 1977, a discovery was made that took the dinosaur extinction debate onto a completely new footing. Walter and Luis Alvarez found abnormally high levels of the element iridium in a clay band that marked the K-Pg boundary in some rock near the town of Gubbio in Italy (see ‘Key observation’, p92). Because iridium is found in much higher quantities in meteorites than in Earth’s crust, they knew that it must have been of extraterrestrial origin. One early suggestion was that a supernova had occurred near our Solar System at that time, but the chemical signature from such an event (plutonium-244) was absent from the samples. Eventually, the father and son concluded that a large asteroid impact, which would have vaporised the iridium-enriched asteroid material, caused the anomaly.

Deep impactBy 1980 a fully fledged theory was launched upon the world by Luis and Walter Alvarez and their colleagues. In summary, an incoming asteroid about 10km in diameter punched a hole in the atmosphere and the Earth’s crust. The energy released, equivalent to hundreds of millions of tonnes of TNT, and matter ejected as the asteroid vaporised, created an enormous dust cloud that led to the K-Pg mass extinction event and death of the dinosaurs. This entirely new hypothesis was met by skepticism from the palaeontological community.

In 1991 the discovery of the 180 to 200km-wide ring-shaped Chicxulub Crater in Mexico crowned the Alvarez theory. Since the asteroid had impacted the continental shelf, this would have released vast quantities of climatically sensitive gases from the carbonate and sulphate-rich layers bound up in the shelf sediments with disastrous effects: extended darkness, global cooling and acid rain.

Despite increasingly strong support for the asteroid theory, there is another extinction theory that must be considered. This focuses on the three massive volcanic eruptions that led to the formation of the Deccan Traps in western India. The Traps, multiple layers of solidified basalt, cover an area that is currently larger than the size

Dr David norman is a palaeontologist at Cambridge University and the author of Dinosaurs: A Very Short Introduction (OUP).

This gravity map shows the extent of the Chicxulub Crater on the Yucatán Peninsula on the coast of Mexico (white line). At 180km in diameter, it’s revealed as the yellow and red concentric rings

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what makes you happy?Readers and facebook fans of BBC Knowledge spill their secrets on

what turns their frowns upside down

Good shopping really makes me happy.- Pooja Kapoor

When I can be...me.- Zehra Chhapiwala.

Studies.

- Nandini M Sangh

avi

The toothless smile of a baby.- Chandramohan Vavullipathy

Whenever I cook food for my parents and when they praise me it makes me really happy. - Meenakshi KapurA warm hug from

my daughter when I return home from office in

the evening.- Aditya Aggarwal

When I play cricket and forget

the world.- Arun Kumar

I feel happy when my son sleeps peacefully. - Puja Verma Saxena

When I help anyone I am happy.

- Abhishek Pandey

Whenever

I recall those first

feelings of love.

- Gurtej Singh.

When I willbecome Bill Gates.

- Pawan Gupta.

When my teacher tells us,

“Don’t worry I will give

you good marks in this test

and will tell you the important

question.”

- Chetan Chaurasiya

In our October 2013 issue, we carried the story ‘How To Buy Happiness’ and conducted a feedback activity on our facebook page, asking fans and readers What Makes Them Happy? Above are our favourites.

Tweeting of birds and swinging of trees makes me happy..- Hema Kumar

When my pa

rents

feel prou

d of me.

- Sreeith

i Raman

When I respect all religions and follow them.- Nishant Bhardwaj

Gossiping.

- Rita Joshii

When I see someone

happy because of me.

- Nupur Sanghi

Flirting.

- Tj’s Xgen

Sleeping when

it rains.

- Malik Nazir

Money...and proper use of it.

- Satyaki Mishra

Machineno ke

sath khelna.

- Chirag Sharma

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Chief education Officer of Aditya Birla Public schools, Shayamlal Ganguli talks about reforms in the education system that will lead to a more holistic structure

What is the motto of Aditya Birla Public Schools (ABPS)?It is Vishnu Puran - Sa vidya ya vimuktaye (i.e. knowledge which liberates). Our resolve is to provide holistic education, which liberates children from the agony of ignorance while empowering and enlighting them. And when we say liberation, it is not just about oneself, it is also about everyone else around. Our education system is strongly rooted in values of integrity, commitment and passion.

What is good education?Good education is something that nurtures the innate abilities of a child. It ensures that the child grows aesthetically, mentally, physically, socially and emotionally. Good education should foster creativity, sensitivity, compassion and care. It is a value-based asset that leads to growth of socially responsible, environmentally conscious and innovative human beings. Education is not just a passport to good life, but a potent and prominent institution used to empower a process that enables children to develop holistically. The mission of our schools is to make education a relevant, meaningful and interesting activity so that our students are ready to face the challenges of the world.

Since your tenure as the cEO of ABPS, what changes have you brought about?I believe in creating schools that provide quality education that is strongly rooted in values. I have tried to build a unique education system that helps to maxmise a child’s potential. I remain deeply involved in all my schools and make it a point to meet everyone right from our stakeholders, children to parents and teachers. Since the time I have come on board, I have

“A teacher affects eternity”

in education

encouraged our schools to act as centres for positive social enhancement and work with the village schools in the neighborhood for their upliftment. And this has been successful to a great extent. We now have 38 value-based socially responsible, environmentally conscious, innovative schools with 40,360 students out of which 17,537 are girls, 22,823 boys and 19,358 from disadvantaged section of the society.

What are your views on using technology to educate children?Well, technology is an integral part of our present as well as future. Our IT labs are well-equipped and all our educators are computer literate and have access to all modern devices. However, our views about use of technology in classrooms is different. No technology can replace the human teacher. We prefer smart teachers to smart classes. Having said that, we are not totally against smart teaching. Our teachers have customised technology to make it function as a supplementary aid.

you have schools in various states. According to you, which state is most progressive and why?The group has established schools in 12 states across the country. I think Gujarat is the most progressive one. Six of our schools are located there. All states have their unique cultural,

92 December 2013

social characteristics and I think it is their diversity that makes building new schools in different states so interesting.

What would you call as your challenges?Education has been a victim of extreme negligence from time immemorial. Even Rabindranath Tagore stressed the need to change the education system in India. Rote learning still plagues our system. Things have sunken to inertia, corruption and lack

of initiative.There are various systemic failures that do not allow our system to bloom. A very hollow teaching system at the primary level and an all-pass promotion policy is the root cause of a very poor academic foundation in the country. The future seems bleak and the quality quotient is declining fast, which

is contradictory to our objective.We are harvesting sub-standard professionals from today’s mushroom institutions.

What improvements are needed then? No education system in the world can be successful without having efficient, proficient and quality teachers. They are the life-line of the whole process but the present scenario shows a pathetic decline in the academic standards, subject knowledge of the teachers, which is indeed a matter of concern and calls for immediate and serious changes. A teacher affects eternity. It’s a fact that no amount of state-of-the-art infrastructure or technology can equal the role of a teacher. The day when teaching becomes the first choice and not the last resort for our young educated generation will be a day when the system will begin to change. Hence, efforts to elevate teachers’ quality should be a priority.

It’s a fact that no amount of state-of-the-art infrastructure or technology can equal the role of a teacher

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On this joyous occasion of Children’s Day, tell us why you should win the BBC Knowledge sweet treat box for your classmates.

Send in your answer, in 50 words or less, complete with your name, age, address, school name by 10 December, 2013 either by email: bbcknowledge@wwm.co.in or post to BBC Knowledge Editorial, Children’s Day Contest, Worldwide Media, The Times of India Bldg, 4th floor, Dr Dadabhai Navroji Road, Mumbai 400001.

Children’s Day Contest

123R

F.C

OM

On this joyous occasion of Children’s Day, tell us why you should win the BBC Knowledge sweet treat box for your classmates.

Send in your answer, in 50 words or less, complete with your name, age, address, school name by 10 December, 2013 either by email: bbcknowledge@wwm.co.in or post to BBC Knowledge Editorial, Children’s Day Contest, Worldwide Media, The Times of India Bldg, 4th floor, Dr Dadabhai Navroji Road, Mumbai 400001.

Children’s Day Contest

BBCK Buzz-v3i6.indd 105 15/10/13 8:36 PM

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x23

94 December 2013

PICtURe seaRCh In the jumble below, the words represented by each of the 16 pictures are hidden either horizontally, vertically or diagonally forward or backwards but always in a straight line. See how many of them you can find? Look out for descriptive names.

sOlUtIONs:

Picture Search: Aeroplane, Australia, Barbell, Bison, Bread, Carpet, Kettle, Nose, Pearl, Piano, Pineapple, Pound, Reindeer, Stage, Topaz, Trumpet

Q1 Go Figure: Easy: 8 + 7+ 2 + 6 = 23Medium: 3 x 4 + 3 + 6 = 21Hard: 3 x 4 - 6 + 2 = 8

Q2 chain Words: Formal, Malice, Icecap, Captor, Torrent, Renting, Ingest, Esters, Erses, Esteem, Teeming, Ingrain, Rainfall, Fallout, Outpost, Postcard

Q3 Deductions: Impeach, Anger, Hit

Q4 Mensa Puzzle: 22. In each row, add the left and right hand numbers and double the answer to give the central value.

Q5 Head & Tail: Trap-Door-Prize-Fight-Song-Book-Bag-Lady

Q6 Pick and choose: Democracy, Sixteen, Papin, Inoculation, Zambia, Magnavox

Q7 Enigma code: Comment, Cement, Smiling, Melting, Compose, Impose, Simpler

Q8 Double Barrelled: FarmIN

OUT

MaZINg Find your way out.

Puzzle Pit

Q2 CHAIN WORDSForm a continuous path of words from START to FINISH by connecting the word parts given in the boxes. There are two parts to each word and the second part of one word is the first part of the next. You won’t necessarily need to visit every box to achieve your aim.START

FOR MAL ICE RENT ING

MING IGN CAP TOR EST

LE ING TEEM ES ERS

PER RAIN FALL SIDE CAR

SON NET OUT POST CARD FINISH

Surprise opening

Something you can win

Important bout

Inspirational anthem

A collection of music

A student might carry one

A homeless person

Q6 PICK AND CHOOSE Solve the six clues, based on the theme of How Do We Know, by choosing the right combination of letter sets given below. Each of the letter set can be used only once and only in the order given. The number at the end of the clues specifies how many sets of letters are used in the solution.

1. Form of government first practised in Greece (4)

2. The origins of cricket date back to this century (3)

3. French physicist who invented pressure cooker (2)

4. Medical practise first used in India around 1500 BC (4)

5. Pigments dating back 40K years were first found here (2)

6. Company which manufactured the first gaming console (3)

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2 6 7 8

Easy = 23

3 3 4 6

Medium = 21

2 3 4 6

Hard = 8

The operators: ÷ X + –

Q1 GO FIGURE Place the four numbers in the first, third, fifth, and seventh boxes and whatever operators you care to use in the second, fourth and sixth boxes in the correct order to get the answer. Use the numbers only once.

Q4 MENSA PUZZLE Which number replaces the blank?

95December 2013

Q3 DEDUCTION You are given a 9-letter word. Your job is to break up this word into 9 separate letters and place them on the dashes to spell a 7-letter word, a 5-letter word, and a 3-letter word. You can use each letter only once.PARCHMENT

I E H

A G

I

Q5 HEAD AND TAIL Look at the clue to solve the answer in the form of a compound word. The second part of the next answer is the first part of the next answer.

H

H

y

S

L

A

O

A

T

A

n

u

r D

E

n

A D

D

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Q8 DOUBLE BARRELLED What word can be placed in front of the five words shown to form in each case another word?

S E

Trap

Lady

Questions and challenges guaranteed to give your brain a workout

Q7 ENIGMA CODE Each colour in our code represents a letter. When you have cracked the code you will be able to make up seven words. The clue to the first word is given to help you get started.

The Clue: Something said

3

6

8

4

2

3

14

16

M

M

M

M

M

M

M

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Puzzle Pit

96 December 2013

AcroSS1 First ever commercially available antibacterial drug (9)5 American inventor who invented the phonograph and a long-lasting

electric light bulb amongst other things (6)8 Invented in 3000 BC it is often reinvented in a futile manner (5)9 The first hand-held mobile phone was developed by this company (8)11 Company which developed the first Personal Computer (3)12 The public introduction of this computer network changed the we

acquire information (5,4,3)15 Antibiotic discovered by Alexander Fleming (10)19 The invention of this semiconductor device played a huge role in the

development of computers and communication (10)22 Joesph ___ was the first person to capture images and print them as

photographs (6)23 Armoured fighting vehicle invented by Ernest Swinton which was

first used in World War One (4)24 Company which has recently begun tests on a self-driving car (6)25 Along with Stanley Mazor he invented the Intel 4004 microprocessor

(3,4)26 Alessandro ____ invented the battery (5)

doWn2 The world’s first mass-produced gasoline powered car was

manufactured by this company (10)3 Philo Farnsworth’s invention which radically changed the

entertainment world (10)4 Pain relief drug invented by Friedrich Sertürner in 1804 (8)6 Mesopotamians in 3000 BC were the first to smelt this alloy (6)7 China’s gift to the publishing industry (5)10 Optical disc storage format, which was invented and developed by

Philips, Sony, Toshiba, and Panasonic in 1995 (3)12 Aviation pioneers ___ brothers (6)13 Charles ____ : Inventor of the first mechanical computer (7)14 Its invention and practical application in the 19th century was the

driving force of the second industrial revolution (11)16 This ancient counting device was first used by the Sumerians around

2500 BC (6)17 The term smartphone was first associated by a phone made by this

manufacturer (8)18 World’s first network to implement TCP/IP protocols and progenitor of

the Internet (7)20 This Chinese dynasty’s reign saw many notable inventions including

movable type, fireworks and fuel coke (4)21 X-rays discoverer (7)

crossword NO.18

Thinknwin

YOUR DetaIls

name:

age:

address:

pincode:

tel:

school/institution/occupation:

email:

Solve & Win BooK hAmPerS

Worth `1000 From

sOlUtION Of CROssWORD NO. 17how to enter for the crossword: Post your entries to BBC Knowledge Editorial, Crossword No.18 Worldwide Media, The Times of India Bldg, 4th floor, Dr Dadabhai Navroji Road, Mumbai 400001 or email bbcknowledge@wwm.co.in by December 10, 2013. Entrants must supply their name, address and phone number.

how it’s done: The puzzle will be familiar to crossword enthusiasts already, although the British style may be unusual as crossword grids vary in appearance from

country to country. Novices should note that the idea is to fill the white squares with letters to make words determined by the sometimes cryptic clues to the right. The numbers after each clue tell you how many letters are in the answer. All spellings are UK. Good luck!

terms and conditions: Only residents of India are eligible to participate. Employees of Bennett Coleman & Co. Ltd. are not eligible to participate. The winners will be selected in a lucky draw. The decision of the judges will be final.

latika sharma Modern Delhi Public School,

Faridabad•

gia Marium titus Mar Baselios Public Shool,

Kottayam•

sameer Patel O P Jindal School, Raigarh

aNNOUNCINg the WINNeRs Of CROssWORD NO. 17

Our pioneers and inventions special!

✂

✂

Puzzle Pit

Dr n c Wadhwa, Vice Chancellor of Manav Rachna International University, talks about how modern education and Indian values need to go hand-in-hand for an all round development of a student

“From being knowledge centric to becoming skill centric would be the biggest game changer”

edu talk

What is Manav rachna international university’s (Mriu) philosophy?Manav Rachna International University (MRIU) is dedicated and committed to train and equip its students with latest knowledge and skills in their chosen fields in the backdrop of Indian ethos and values to enable them to face global challenges.

How is this inculcated into everyday university life?The essence of MRIU is infused into students through academic and administrative policies, processes and procedures. The objective is to impart knowledge through various domains while inculcating soft skills like leadership, esprit-de-corps and communication.

What according to you signifies complete education? How does the university encourage this?It’s the development of a harmonious personality with scientific and spiritually trained minds.The university encourages this by conducting seminars, conferences, declamations, sports-related events, colloquia, scholastic activities and other cultural and student-oriented activities.

What is the one intangible educational/ learning element that the students are offered at Mriu, which sets it apart?Besides imparting excellent domain knowledge and skills of highest order, we believe in imparting rich values to students that make them rooted with their culture and heritage and also enables them to face challenges with ease.

How does the university prepare its students for their career?We have a career development centre and a corporate resource centre that helps in equipping students with relevant knowledge

and soft skills that are required to enhance employability and relevance to employers.

Since your tenure as the vice chancellor of Mriu, what changes have you brought about? I facilitated this campus in its transformation from a college of repute into a university framework through introduction of competence-based curriculum, robust examination and evaluation system. I have also introduced latest teaching learning processes through pedagogical techniques while establishing symbiotic academia-industry connect and developing collaborations with international universities.

What are your views on using technology to educate students? Does the university implement any technological learning tools?Technological interventions in teaching learning processes are indispensable. We use a learning management system in our pedagogical delivery.

What are the next big steps you would want Mriu to implement?The essence of MRIU is infused into students through academic and administrative policies, processes and procedures. The objective is to impart knowledge through various domains while inculcating soft skills like leadership, esprit-de-corps and communication.

What do you think would be the challenges for accomplishing Mriu’s goal?Availability of quality faculty, diminishing quality of student inputs and decline in value system are some of the challenges we face.

What improvements according to you if any, in the existing education system would benefit the students?The approach from being knowledge centric to becoming skill centric would be the biggest game changer to bring about improvement in the educational paradigm prevailing in the country.

97December 2013

A definitive list of gadgets this year, which are not too late to own

98 October 2013

gadgeTs of 2013

• sMaRthINgs Ever wished if everyday objects around us

would help us in making our lives secure. Well, the people at SmartThings have made that

happen by creating a variety of small sensor devices and a central hub, called SmartThings,

which you can place around your home or office or car. These sensors communicate with each other and let you turn lights, locks, TV, AC

etc into smart objects that can be instructed to perform a function you desire by a push of a button. Get real time updates on when your

children unlock the door to your house or have the lights in your house light up at a pre-determined time when you are on a vacation.

Price: `18,553 • www.smartthings.com

• playstation 4 One amongst the various mobile integration features in the new Sony PlayStation 4, is that it will allow users to purchase a game online through their smartphone from anywhere in the world and while doing so it will install the game in the console at home. PS4 is also about 9 times faster than PS3 thanks to the newly developed 8GB GDDR5 RAM. The PS4 Dualshock 4 controller comes with 12 buttons, a touchpad and motion sensor. Time for a Grand Theft Auto V marathon run then eh?

Price: `25,000 • www.techradar.com

• fORM 1 3D PRINteRAlways wanted to see your drawings take form in real life? The Form 1 3D printer lets you just do so. Using the stereolithography technology where a laser beam drawing on a tray of liquid plastic resin solidifies a thin layer of it, the printer can create intricate designs, in varying resolutions and thickness measuring between 0.025-0.1mm. It is compact and compatible with Macintosh and Microsoft printers.

Price: `2,08,434 for the unit • www.formlabs.com

• FujiFilm FinepixThe 12 megapixel Fujifilm FinePix X20 is equipped with a large optical viewfinder, delivers sharp images and comes with

HD video recording. Apt for photography in low light, the X20 also has manual 4X

optical zoom lens and a 2.8 inch LCD monitor. The camera allows editing of

pictures with its in-built RAW data converter.

Price: `39,999 • www.fujifilm.com

The soon-to-be launched Microsoft Xbox One would come with improved Kinect, motion sensor camera, which would not only trace your body movements but also detect facial expressions. Its HDMI in and out port would allow seamless navigation between gaming and viewing TV. With integration of Skype’s audio codec, Xbox One would offer higher quality voice chat than its sibling Xbox 360.

Price: `31,511 • www.cnet.com

• xbox one

A definitive list of gadgets this year, which are not too late to own

gadgeTs of 2013

• lg CURveD tvLG’s 55” curved OLED TV has a concave screen of 4.3mm

depth, a dual-core processor, voice control, SmartTV interface with in-built W-Fi and LAN port. The device doubles as a 3D TV with depth and viewpoint control;

allowing for an uninterrupted view of the screen from any angle. A white pixel addition to the traditional three colour pixels ‘red, green and blue’ allows for better colour display.

Price: `6,31,491 • www.lg.com

• GooGle nexus 5The Google Nexus 5 is rumoured

to be a HD 5” or 5.2” screen smartphone. Reports have

suggested that the phone will have a 13 megapixel rear camera

with flash and a 2 megapixel front camera while being powered

by quad-core Snapdragon 800 processor. Whether it

will be released with the new Android KitKat is doubted. The

speculated date of release is mid-October or late November.

Price: Not available • www.cnet.com

• sony Dsc-qx100It might look like a lens, but it acts like a camera. Clip on the

lens style cameras DSC-QX100 by Sony, to your smartphones to click pictures. A 64GB memory card, rechargeable battery, a shutter release make it a better camera for your phone or tablet

and should be on your ‘things to buy for Diwali’ list. Don’t let your credit card tell you otherwise.

price: Dsc-qx100 `31,572 • www.sony.co.uk

• BOse BlUetOOth sPeakeRThe Bose SoundLink Mini Bluetooth Speaker is a compact

lightweight speaker that can play music; remembers a total of six paired devices; tablets, smart phones, iPods. Control buttons are on top for volume and an auxiliary button to connect with devices

without Bluetooth for times when the network falters.

Price: `16,200 • www.complex.com

• samsunG Galaxy Gear smart-watchOne word: Want! Samsung’s Galaxy Gear smart-watch, can control

music, receive messages, update Facebook status and also make calls via Bluetooth, without actually using your Samsung

smartphone. The gesture controlled interface device comes with call facilities; a speaker and two microphones near the 1.63“ OLED

display screen, a battery life of 27 hours, pre-programmed 70 apps and a 1.9 megapixel camera located on the strap that takes pictures and comes with video recording and playback. The Gear

is equipped with a buckle and flexible band, which can be adjusted depending on the shape and size of your wrist.

Price: `23,500 • www.gadgets.ndtv.com

resource

Here, some of the best educators and animators from around the world are brought together to make lessons you’ll actually want to watch. From giant sea creatures, to dark matter and big data, each video is a short, snappy and visually appealing look at one aspect of life, the Universe, and everything in it. You’ll learn something, but you’ll hardly notice.

California scientists have thousands of bugs sitting in storage, with labels detailing when and where they were found. But without you, these creatures may never be digitally catalogued. This citizen science project aims to create a database of over one million specimens that will help to pinpoint how these tiny creatures have been affected by climate change.

20 years ago, CERN put the World Wide Web in the public domain, making it available for anyone to use, royalty-free. The rest is history. Now there are an estimated 630 million websites, and CERN is on a mission to recreate the web’s own history by putting the first website back online. Follow the team’s progress on their blog and see the website itself.

This simulator lets you see what the Planck satellite’s map of the cosmic microwave background would look like if the proportions of normal matter, as well as the other two more elusive components of the cosmos, dark matter and dark energy, were different. You can then see what fate – a big crunch or a big freeze – the Universe would meet with your chosen mix.

Website Website WEBSiTE

WEBSiTE WEBSiTE WEBSiTE

TED EDcalbug

The first websitecMB SiMuLATOr

www.youtube.com/TEDEducationwww.notesfromnature.org/#/archives/calbug/

first-website.web.cern.chwww.strudel.org.uk/planck/

Wartime codebreaker Alan Turing would have been 100 last year and the Science Museum in London has an exhibition to celebrate the great man’s work at Bletchley Park. But if you’d like to find out how you’d fare as a code cracker, look no further than these 10 challenges created by GCHQ. There are hints, but you won’t make the leader board without going it alone.

There are so many great science videos and podcasts online that it can be hard to find the real gems. Luckily, Science Studio has tracked down some of the best for you. Sit back and watch as a 2000-year-old analogue computer is recreated in Lego, and listen to an acoustic tribute to the Space Shuttle. Results for this year’s best multimedia science on web will be announced on October 2013.

Science Studio

turinggame.sciencemuseum.org.uk

thesciencestudio.org

if you have a favourite website, blog or podcast that you’d like to share with other readers, please email bbcknowledge@wwm.co.in

Our pick of internet highlights to exploreget your clicks

cODEBrEAKEr

100December 2013

grand Theft auto v

PS3, xbox 360, rockstar, `2,900

total War: Rome IIPc, creative Assembly, `1,499

Developer Creative Assembly returns to the setting of its most lauded game: classical antiquity-era Rome, where pristine togas and stabbed backs are the order of the day. As before, the action unfolds in two distinct arenas. On the field of battle you’ll command up to 40 units at once in epic, tactical conflicts, then on the campaign map you’ll manipulate political factions, convert rivals to your cause, and assassinate your enemies. Dulce bellum inexpertis, as the old saying goes - but don’t let that put you off.

PuppeteerPS3, Sony Japan, `1,999

Have you heard about the Moon Bear King? Neither had we, but apparently he likes to rob children of their souls to provide his castle with a constant reserve of ghostly servants. In this snazzy platformer from Sony Japan, the lunar-based ursine monarch rips the head off a small boy, Kutaro, who then attempts to regain his cranium with the help of a magic pair of scissors. It’s a bewildering plot, but marionette-like characters grant Puppeteer an instantly memorable look.

New super luigi UWii u, nintendo, `1,769

Take pity on Luigi: despite being significantly taller than Mario, he’ll always be trapped in his brother’s shadow. This is a disc release of what was originally a downloadable add-on for New Super Mario Bros U, featuring stages that are much shorter than those in the original game, but also a darn sight tougher too. Luigi himself is fiddly to control, with a freakishly high jump that takes time to master. Poor guy - even in his own game, he plays as a bit of a weirdo.

So, here it is. The arrival of a new Grand Theft Auto is always a notable event, but this one feels particularly significant. A five-year wait has fuelled expectation to dangerously insane levels; if Marty McFly had parked his DeLorean in front of the GTA hype train, it’d probably be in a dinosaur’s colon by now.

Still, it’s hard not to be excited by the raw facts. This is the biggest game that Rockstar has ever made, a project so huge that the Xbox 360 version has to come on two discs. Its virtual world is five times bigger than the Western wilderness of Red Dead Redemption, encompassing the city of Los Santos (Rockstar’s satirical take on LA) and miles upon miles of surrounding

GTA’s Michael was starting to feel the

psychological strain of going on his

seventeenth murderous crime spree in as

many days

revIeWs

countryside. You can scuba dive. You can leap out of a plane. You can steal a policeman’s car, drive it the wrong way down the motorway, and crash it into the sea - indeed, this is still bound to be what most of us do the first time we play. Just because you can.

There are new ideas, too. Where previous GTAs offered one muddled antihero, here there’s a trio of them: retired mobster Michael, adrenaline junkie Franklin, and a psychotic ex-army pilot named Trevor. You can switch between these miscreants at will, even in the heat of a mission, offering three perspectives on whatever carnage happens to be at hand. Customisable heists are a major focus of the action, so expect to spend a lot of time planning robberies and assembling a bespoke crew of professional undesirables.

And if all that wasn’t enough, there’s also an extensive multiplayer mode, with your tailored avatar essentially standing as the game’s fourth character. Rockstar wants GTA Online to gain a serious online following; whether it succeeds or not, expect to be playing this for months.

alsO OUt

101December 2013

games

started learning karate in 1998 in Hyderabad, when I was only 8-years-old. My parents had put

me in the karate classes because I used to get bored at home as I was their only child. We had just moved from Haryana and as I didn’t know Telugu; I had very few friends. I learnt to love karate because action was the only language there and the game gave me the attitude to fight back and never give up. It also helped me develop flexibility and improve my reactions. Later, when my parents directed me to badminton, I carried the same attitude and learnings to the court.

My first coach, Aarif sir, took me under his wing and it is because of him that today I have turned into a good badminton player. I won my first under-10 tournament in July 1999, where the prize money was just `150!

When I step onto the court, the first thought that enters my mind is to only win. I focus only on the game and try to forget everything else. Yes, there is pressure and that is a difficult issue to handle. Everybody is nervous before the start of the game. I believe that if you have worked hard and are confident about your abilities, then the

pressure disappears as soon as you enter the court. I try not to let setbacks that I experience undermine my efforts. I put in extra into my training the next day, reminding myself that I shall not repeat the same mistakes. It is difficult every time and sometimes I do feel dejected. But, my biggest motivation is my love for the game, and that is what helps me move forward.

Self-belief is the key to remain focused. A small mistake can bring you down quickly. Also, a mentor is of utmost importance. It is he/she who transforms you, from a mere player to a player of repute

Saina nehwal is ranked number four on the Badminton World Federation list and is the first indian to win a bronze medal for badminton at the 2012 Olympics. She has been conferred the Padma Shri, Arjuna Award, and the rajiv Gandhi Khel ratna by the Government of india for her achievements. As part of the indian Badminton League, she plays for Hyderabad Hotshots.

Olympic winner Saina nehwal talks about the essential ingredient for succeeding, a never-say-die attitude

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102 Decemer 2013

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“Yes, there is pressure and that is a difficult issue to handle”

and skill. For me, Pullela Gopichand has done this for me. As the former All England Open Badminton champion, he has given me my game, courage, die hard attitude. I always try to put his words into action.

When I was in school, it was difficult for me to balance sports and education. While I was not born a sportsman, I chose to participate in sports. I tried to divide my time and energy equally for both, and pursued my studies at the Bhartiya Vidya Bhavan’s Vidyashra in Hyderabad till culmination. I do understand the importance of education, and in India it is very difficult to achieve this balance. I decided to focus my energies only on badminton, a decision I have never regretted. I think whatever I planned for has come true.

My biggest motivation is my love for the game, and that is what helps me move forward

SCIENCE • HISTORY • NATURE • FOR THE CURIOUS MIND