physicsworld january 2005 physicsweb.org volume 18 no...

PhysicsWorldV O L U M E 1 8 N O 1J A N U A R Y 2 0 0 5 p h y s i c s w e b . o r g

Einstein 2005

P H Y S I C S W O R L D J A N U A R Y 2 0 0 5

3 POST-DEADLINEDrawing a line under a force microscope, the physics of sound in the Sahara,how does water boil?

5 NEWS AND ANALYSISLocal difficulty for the cosmic background, Google targets scientists,massive Antarctic neutrino detector takes shape, ups and downs for physicsdepartments in UK universities, contract to manage Los Alamos goes up for grabs

13 EINSTEIN 2005Ahead of his time Peter RodgersA brief history of Albert Einstein Matin DurraniEinstein and the International Year of PhysicsFive papers that shook the world Matthew Chalmers

19 Einstein’s random walkFew physicists believed that atoms were real before Einstein’s theoretical work on Brownian motion paved the way for experimental confirmation,as Mark Haw describes

The 1919 eclipse: a celebrity is born Matthew Stanley

27 Relativity at the centenaryAs we enter a new era of experiments, Einstein’s general theory of relativity remains the leading theory of gravity, as Clifford M Will explains

Einstein and his love of music Brian FosterLooking after the image of a legend Peter Gwynne

37 The search for gravitational wavesThe detection of ripples in the fabric of space–time is one of the outstandingchallenges in experimental physics. Jim Hough and Sheila Rowan report on progress

A very special centenary Robert BluhmStrange ways of light and atoms Charles W ClarkQuiz: Do you play dice?

47 The power of entanglementEinstein disliked the random nature of quantum mechanics but he was stillinfluential in the development of the theory, as Harald Weinfurter relates

The other side of Albert Einstein Tim ChapmanThe king is dead. Long live the king! Robert P CreaseEinstein’s quest for unification John Ellis

58 CAREERSHow to be a patent attorney Simon MounteneyOnce a physicist…Wolfgang Heckl, careers update, movers and shakers

63 RECRUITMENT

72 LATERAL THOUGHTSAn evening with the Einsteins Lady Neysa Perks

Relativity – putting Einstein to the test 27–32

Brownian motion – atoms made real 19–22

Gravitational waves – still searching 37–41

Physics World is published monthly as twelve issues perannual volume by Institute of Physics Publishing Ltd, Dirac House, Temple Back, Bristol BS1 6BE, UK

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PhysicsWorld

Quantum mechanics – entanglement 47–51

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Scientists in the Netherlands have modifiedan atomic force microscope so that it canwrite and etch sub-micron patterns on asurface with molecular “ink”. Atomic forcemicroscopes (AFMs) were originally de-signed to study surfaces by monitoring theinteraction between an extremely sharp“tip” and the test material, but they can beused for surface modification as well. In thenew device the ink flows from a reservoirthrough a microfluidic channel in the canti-lever that holds the tip and then on to the tip itself (S Deladi et al. 2004 Appl. Phys. Lett.85 5361).

Using 1-octodecanethiol as the ink, MikoElwenspoek and colleagues at the Univer-sity of Twente drew lines just 0.5 µm wideon a gold substrate. The ink reacted with thegold to produce a stable monolayer struc-ture on the substrate. In separate experi-ments with a commercial etchant, the tipwas able to etch trenches just 0.3 µm wide

and 14 nm deep in a chromium surface.The team used the technique to draw and

etch straight lines, but any pattern could,in principle, be created. It might also bepossible to reduce the width of the lines andthe trenches further by sharpening the tip of the AFM.

Elwenspoek and co-workers say their de-vice is an improvement on existing AFM-based surface-modification techniques, like“dip-pen lithography”, because it can holdmore ink and the flow of the ink can be con-trolled more precisely. Moreover, by cre-ating a local environment around the tip,the operation of the device is not affected by humidity in the atmosphere.

The pen could be used in new nanofabri-cation techniques to create 3D nanostruc-tures, and the Twente team now plans to dofurther work on the device itself and also onthe ink, including improvements to its vis-cosity and wetting properties.

Microscopic ‘pen’ rewrites the rules

From Marco Polo onwards explorers havetold stories about strange sounds they haveheard in the desert. It is known that sounds are produced by sand dunes when they aval-anche, but the exact mechanism behind thephenomenon has remained a mystery. NowBruno Andreotti of the University of Paris 7has proposed that the sounds come fromvibrations in the sand bed that have beenexcited by collisions between sand grains (B Andreotti 2004 Phys. Rev. Lett. 93 238001).

“Singing dunes are one of the most puz-zling and impressive natural phenomena I have ever encountered,” says Andreotti.“The sounds can be heard up to 10km awayand resemble the beating of a drum or thenoise of a low-flying jet.” The dunes pro-duce sounds that are as loud as 105 dB –roughly equivalent to a car horn – and havefrequencies between about 95–105 Hz.

The French physicist took his equipment– including a microphone, digital audio tape and accelerometer – from Paris to theAtlantic Sahara in Morocco, which containsmore than 10 000 crescent-shaped dunesknown as barchans. The wind in the desertcan erode the back of these dunes, causingsand to build up at the top. When too muchsand has accumulated, an avalanche occursand the dunes start to “sing”.

Andreotti simultaneously measured vi-brations in the sand bed and acoustic emis-sions in the air, and was then able to extractinformation about the frequency, amplitudeand the phase of these signals. He foundthat the vibrations in the sand behaved likeslow-moving elastic sound waves that werelocalized at the surface of the dune and hadan amplitude that was about a quarter ofthe diameter of an individual grain of sand.

“The sounds are produced when grainsdrum against one another, exciting elasticwaves on the dune surface, with the vibra-tion of the sand bed tending to synchronizethe collisions,” says Andreotti. “In manyways the surface of the sand bed acts like themembrane in a loudspeaker.”

Physicist solvesdesert mystery

p h y s i c s w e b . o r g

Singing dunes – in order to study the sounds ofdesert sand dunes, Bruno Andreotti first had totrigger avalanches by sliding down the dune face.

Boiling water inside a computer

Although the boiling of water is one of the best-known examples of a phase transition, what happens atthe level of molecules during this apparently simple phenomenon is not so well understood. In particular,little is known about the start of the process when regions of gas vapour begin to form in the liquid. NowDirk Zahn of the Max Planck Institute for Chemical Physics of Solids in Dresden has taken a major stepforward in the study of evaporation by simulating the behaviour of 256 water molecules at a temperatureof 100 °C (D Zahn 2004 Phys. Rev. Lett. 93 227801). Even though this represents a volume of water ofjust 2.1×2.1×2.1 nm, the computational demands of the simulation meant that the trajectories of themolecules could only be followed for a fraction of a microsecond. However, this was long enough toreveal the beginning of the phase transition, when vacuum cavities (yellow regions in the image above)spontaneously form in the liquid phase of water as a result of the breaking of hydrogen bonds. Nearbycavities then begin to merge into larger vacuum domains, while others quickly disappear, and the watermolecules at the liquid–vapour interfaces tend to leave the liquid surface. Eventually these evaporationevents outnumber the competing process whereby the molecules return to the liquid phase. Zahn is nowapplying the technique, developed by David Chandler and co-workers of the University of California atBerkeley, to other phase transitions such as the evaporation of alcohol during the distillation process.

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The cosmic microwave background is oftencalled the echo of the Big Bang, but recentresearch suggests that some of its featuresmight have their origins much closer tohome. Although most cosmologists thinkthat the tiny variations in the temperature ofthe background are related to quantum fluc-tuations in the early universe, Glenn Stark-man and colleagues at CERN and CaseWestern Reserve University in the US havenow found evidence that some of these vari-ations might have their roots in processesoccurring in the solar system. If correct, thenew work would require major revisions tothe standard model of cosmology.

The cosmic microwave background wasformed about 380 000 years after the BigBang, when the expanding universe hadcooled enough for electrons and protons toform hydrogen atoms. In the early universethese electrons scattered the radiation cre-ated in the Big Bang, but when this scatter-ing stopped, the density distribution of theuniverse at the time became imprinted astiny fluctuations in the temperature of themicrowave background. These variations indensity eventually became the large-scalestructure of galaxies and clusters of galaxiesthat we see in the universe today.

The detection of fluctuations in the cos-mic background by the COBE satellite in1992 was a milestone in the history of cos-mology, and subsequent experiments – no-tably the Wilkinson Microwave AnisotropyProbe (WMAP), which was launched in2001 – have measured the background inmore and more detail. Cosmologists plot themagnitude of these fluctuations as a func-tion of the angle they subtend across the sky,with different angular scales like musicalharmonics, each with a different frequency.The lowest harmonic is almost entirely dueto the Doppler-shifted motion of the solarsystem through the universe: the microwave

radiation is very slightly hotter in the direc-tion in which the solar system is moving and cooler in the reverse direction. This “di-pole” harmonic has a hot spot at one end ofthe sky and a cold spot at the opposite end.

In analysing their data, physicists workingon the WMAP mission have to subtract thisradiation from the rest of the signal so thatthey are left only with the temperature fluc-tuations created at the time of the Big Bang.But Starkman and colleagues have foundstrong evidence that the second harmonic,the “quadrupole” (two hot spots and twocold spots), and the third, the “octopole”(three hot and cold spots) also have theirorigins in the solar system. When they com-bined the fluctuations from the quadrupoleand the octopole on the map of the sky, theyfound that the plane of the solar systemthreads itself through the resulting hot andcold spots (see image), suggesting a link be-tween the orientation of the solar system andthe formation of these temperature fluctu-ations (2004 Phys. Rev. Lett. 93 221301).

Other results appear to support this sug-gestion. For example, the relative magni-tude of temperature differences in oppositehalves of the sky is greatest when the sky isdivided up along the plane of the solar sys-

tem. Starkman estimates that the odds of allof these different pieces of evidence being afluke are anything up to a million to one.

“Each of these correlations could just bean accident,” says Starkman. “But we arepiling up accident on accident. Maybe it isnot an accident and, in fact, there is somenew physics going on.”

What might this new physics be, assumingthere is not some subtle misunderstandingof the WMAP instrument? The first pos-sibility, according to Starkman, is that thesolar system has some previously unknownproperty, or contains additional matter thatcan emit or absorb microwaves. Second, hesays, cosmologists might have to revise thegenerally accepted idea that the very earlyuniverse underwent a period of extremelyrapid expansion, known as inflation, justafter the Big Bang. The inflationary modelpredicts fluctuations in the microwave back-ground of about the size found by WMAP(in fact, slightly larger), so subtracting theforeground contribution from the solar sys-tem would leave this model wanting.

Charles Bennett of NASA’s GoddardSpace Flight Center, who is WMAP’s princi-pal investigator, is cautious about their con-clusions. “While the a priori probability of thealignments [between solar system and tem-perature fluctuations] is low, the alignmentsare seen as a result of an a posteriori selection,”he says. “So their significance is uncertain.”

But Pedro Ferreira, an astrophysicist atOxford University, says he would be sur-prised if there were no local contributions to the microwave background. “The data we have on our galaxy are not as precise asthose produced by WMAP,” he says. “Whichmeans that we cannot really take the WMAPdata, use another accurate map to removethe effect of the galaxy and see what is left.To some extent we have to guess.”Edwin Cartlidge


Doubts cast over map of cosmos


Local effect? – astrophysicists have found that theplane of the solar system (dashed line) threadsitself through hot and cold spots (circles) in thecosmic microwave background, suggesting thatsome of the variations in the latter are not causedby events that took place in the early universe.

A collaboration of physicists from sixEuropean countries and the US has beenawarded part of the European Union’sDescartes research prize for work onquantum cryptography. The IST-QuCommcollaboration consists of research groups in Sweden, Germany, France, Switzerland,Austria and the UK, plus a team from the Los Alamos National Laboratory in the US.They share the 71m prize with life scientistsstudying mitochondrial DNA.

Quantum cryptography allows two partiesto share a secret “key” – encoded with

single photons – so that they cancommunicate much more securely than ispossible with existing cryptographictechniques. Any attempts by a third party toeavesdrop on the communications can bereadily detected. Quantum cryptographycould have applications in everything fromelectronic communications to e-bankingand e-voting. The IST-QuComm consortiumlast year performed the first ever quantumcryptographic bank transfer over a 6 kmfibre-optic link in Vienna.

Meanwhile, Wolfgang Heckl, who is

director general of the Deutsches Museumin Munich, has been awarded the first everDescartes prize for professional scientistsinvolved in science communication. He wasgiven the 750 000 prize for his ability toexplain complex scientific topics in a simplemanner. Heckl, who appears regularly in theGerman media, was previously a physicist atthe Ludwig Maximilans University inMunich, where he ran a centre fornanobiotechnology. He joined the museumlast October (see page 60).Belle Dumé and Matin Durrani

Quantum-cryptography research scoops Descartes prizeAWARDS

N E W S A N D A N A LY S I S


Can’t find that reference to a key paper onquantum cryptography, or want to locate areference text on spintronics? The Internetsearch engine Google now has a tool to helpresearchers seek out scholarly literature thatis stored or cited online. Google Scholarworks in a similar way to the generic Googlesearch facility. The main difference is that itfocuses its search on peer-reviewed papers,theses, books, preprints, abstracts and tech-nical reports, rather than trawling througheach and every document on the Internet.

Results to queries are ranked using aproprietary algorithm that takes into ac-count the full text content, the publication inwhich it appeared, and its citation record.This should mean that seminal papers inrespected journals are ranked higher than,say, Web blogs on identical topics. Thesearch tool also lists works that are not avail-able on the Internet but are still cited byother researchers.

Google Scholar is currently available forfree as a “beta” – or test – version while the

company evaluates its good and bad points.Researchers are also being encouraged totest the relevance of scholarly searches forthemselves. However, physicists can alreadyfind most papers they need on the arXiv.organd Spires databases, and will find GoogleScholar most useful for retrieving referencesto historic papers and books.

Yet unless publishers or libraries actuallyput the text of historical works online,Google Scholar will not help physicists toaccess older materials either. “Our libraryhas its historical papers in a cellar, whereone has to climb down ladders to consultthem,” says Gerard ’t Hooft, the Nobel-prize-winning theorist from the Universityof Utrecht. “Google Scholar appears toprovide access to some of these, but not all.”

Google is planning to collaborate withseveral US research libraries and OxfordUniversity to digitize their collections, buthow much will be put online is not known.Paula Gould● scholar.google.com

Google adds scholarly search enginePUBLISH ING

Irish astronomers want the government tohelp reverse a decision to end research at theDunsink Observatory, the oldest scientificinstitution in Ireland. Four academic staffplus a number of support staff and threePhD students are currently involved in re-search at Dunsink, but they are all employedby the Dublin Institute of Advanced Studies(DIAS), which has decided to move them to its headquarters in the centre of Dublin at the end of this month. Over 150 astron-omers have signed a letter to the minister foreducation and science, Mary Hanafin, ask-ing her to intervene.

Founded in 1783 on a hill about 8 kmfrom Dublin, research at Dunsink is focusedmainly on active galactic nuclei, galaxieswith starbursts and clusters of galaxies.DIAS decided to move its staff from theobservatory after an international panel ofresearchers, chaired by Alan Green of ETHZurich, reviewed its activities at Dunsink.“The panel’s recommendations are basedon review of the academic work, the staffinglevels and its physical location,” says CecilKeavney, the institute’s registrar. “We areintegrating the research staff at Dunsinkunder one roof toward the greater efficiencyfor Irish research astronomy.”

However, many Irish astronomers dis-agree. “We believe that aborting its researchnow sends the wrong message about the cur-rent state of Irish astronomy,” they write in

their letter to Hanafin. They are worried that“closure in the short term leaves the observa-tory very much at direct physical risk”. Theyalso point out that Ireland is about to ce-lebrate the 200th anniversary of the birth ofDunsink’s most famous director, the mathe-matical physicist William Rowan Hamilton.

“Why don’t they just do a proper study of the alternatives and not act precipitouslylike this,” says Brian McBreen, the astron-omer at University College Dublin who or-ganized the letter to the government. “Theobservatory lies on 14 acres of land so whynot avail of that and expand its educationaland outreach activities, perhaps with a plan-etarium or something similar.”John MooreCork, Ireland

Astronomers oppose move to DublinIRELAND


SIDEBANDSOxbridge tops scientific tableCambridge University is the best in theworld at science, according to a surveycarried out by the Times Higher EducationSupplement. The survey ranked universities’performance in science based partly on asurvey of 1300 academics in 88 countriesand partly on quantitative measures, suchas the number of citations that eachfaculty member receives. Eachuniversity’s score was normalized to thatof Cambridge, which received 200 points.Oxford was second with 169.8 points,followed by Harvard (159.8), Caltech(159.0) and the Massachusetts Institute of Technology (135.1). However, if theuniversities are ranked only in terms ofcitations, then the US scoops the first 16 positions, with Harvard in the top spot.The highest ranked university outside theUS is the ETH Zurich in Switzerland in17th place, followed by Durham (18th)and Cambridge (19th).

Magnetic effects seen in waterPhysicists in Japan have discovered thatthe melting point of water increasesslightly in a strong magnetic field.Hideaki Inaba and colleagues at ChibaUniversity found that it increases by5.6 mK for ordinary water in a field of6 T, and by 21.8 mK for heavy water(2004 J. Appl. Phys. 96 6127). Inaba’sgroup found that the changes in themelting points were proportional to thesquare of the magnetic field. “We believethat the thermal motion of the partiallycharged atoms in the water gives rise to aLorentz force when a magnetic field isapplied,” says Inaba. “By suppressing thethermal motion, the Lorentz force makesthe hydrogen bonds stronger, which couldaccount for the rise in the melting points.”

US airports look to terahertz screeningThe US government is giving $0.5m toterahertz pioneers TeraView to develop adevice that can detect explosives in airlinebaggage. The UK-based company will beworking with US X-ray inspection andtrace detection experts Smiths Detection.Together they will explore how terahertzimaging could enhance the screening ofexplosives in hold luggage. Researchershave 12 months to develop a next-generation security system that impressesofficials from the US Department ofHomeland Security. If successful, thetechnology could be fitted in every USairport by 2010. In a separate project,TeraView has received funding from theUK government to develop a hand-heldwand for screening airline passengers fortraces of explosives at check-in.

Under threat – the Dunsink Observatory.



Later this month scientists and engineersworking at the south pole will lower a stringof light sensors down a hole in the ice morethan 2km deep. Over the next five years theywill lower about 80 such strings, creating a network of light sensors embedded in theice to form a telescope known as IceCube.Their aim is to detect cosmic neutrinos –chargeless, almost massless particles that aregenerated by extreme astrophysical phe-nomena such as exploding stars. As well asproviding a new view of such phenomena,these neutrinos could help us find dark mat-ter and reveal the origin of cosmic rays.

Neutrinos are useful as astronomical mes-sengers because they hardly interact withother matter. This means that they can passthrough regions in space that absorb elec-tromagnetic radiation, such as gas clouds or the all pervasive cosmic microwave back-ground. But the neutrinos’ virtue is alsotheir vice: their weak interaction means theyare extremely difficult to detect. Doing sorequires building extremely large detectors,so that if there are enough atoms in the tar-get a neutrino will interact with one of themsooner or later.

An astrophysicist in the US even thinksthat a neutrino detector could be developedusing one of Jupiter’s moons (see box). Butfor the time being, researchers are sticking todetectors on Earth. IceCube, which will cost$270m, is being developed by researchers in the US, Germany, Sweden, Belgium andJapan, and will occupy a volume of 1km3,with the strings (electrical cables) distributedover an area of 1km2. Each string will con-tain 60 sensors – photomultiplier tubeshoused in protective glass spheres – distri-buted evenly along the lowest 1km of cable.Neutrinos reaching the Earth’s northernhemisphere will pass through the planet and occasionally interact with a proton or a neutron in an atomic nucleus to create an-other subatomic particle called a muon. Anymuons generated in or just below IceCubecan be detected by the Cerenkov radiationthey give off as they travel at high speedthrough the ice. This radiation will allowphysicists to determine the flux and traject-ory of the incoming neutrinos. The detectorwill be deep enough to screen out cosmic rays– the stream of charged particles that con-stantly bombards the Earth – generated inthe southern hemisphere and dark enough to avoid interference from natural light.

A prototype of IceCube has already beenoperating at the south pole since 2000.Known as AMANDA, this experiment hasproved the feasibility of observing neut-rinos in the ice, having so far detected about4000 neutrinos, with energies up to about

1015 eV, generated by cosmic rays passingthrough the Earth’s atmosphere near thenorth pole. But AMANDA has only 1.5%of the volume of IceCube and has beenunable to detect any higher-energy cosmicneutrinos, which are much rarer than theiratmospheric counterparts.

That will not be the case with IceCube,which is predicted to detect neutrinos froma number of astrophysical sources withenergies up to 1018 eV. These include themysterious sources of cosmic rays. Astro-physicists have some evidence that cosmicrays are accelerated near black holes – poss-ibly those associated with active galaxies orgamma-ray bursts – but detecting neutrinosfrom these objects would prove this, accord-ing to IceCube’s principal investigatorFrancis Halzen of the University of Wis-consin-Madison in the US. This is becauseneutrinos are generated by the decay ofparticles known as pions and kaons, whichthemselves result from the decay of protons(cosmic rays).

IceCube will also search for “weakly inter-acting massive particles” (WIMPs), whichsome cosmologists think could be a source ofdark matter. It will do so by looking out forthe neutrinos given off in the annihilation of very massive WIMPs in the centres of theSun and Earth.

Halzen says that IceCube should find itsfirst cosmic neutrino well before it is finishedin 2010, and that the completed instrumentis expected to detect hundreds of events peryear. But he adds that it would be disap-pointing if the experiment only found whatwas expected to exist. “I would not be doingthis if there were not opportunities for dis-covering new things,” he says.

Also following in AMANDA’s footstepsare two experiments being constructed inthe Mediterranean Sea. ANTARES will usephotomultiplier tubes on strings attached tothe sea bed off the south coast of France,while NESTOR will involve a rigid tower ofsensors fixed to the sea bed off the Greekisland of Pylos. Due to be completed withinthe next couple of years, these experimentsare about the same size as AMANDA andfollow on from a smaller experiment locatedin Lake Baikal in Siberia.

But physicists working on the projectshope that they can eventually use the ex-pertise that they have gained developingthese experiments to build an underwaterdetector with a volume of 1 km3, sometimeafter 2012. “Neutrino astronomy is notgoing to take off unless we build a 1 km3 de-tector in the northern hemisphere as well,”says Halzen.Edwin Cartlidge

Antarctic ice set to probe the universeNEUTRINO ASTRONOMY


Peter Gorham of the University of Hawaiibelieves that to observe highly energeticcosmic neutrinos (with energies of about1020 eV) physicists should consider makinga detector out of Europa, the ice-coveredmoon that orbits Jupiter (arXiv.org/abs/astro-ph/0411510).

When neutrinos with energies of 1020 eVinteract with ice, they produce Cerenkovradiation at radio wavelengths (as well as atvisible wavelengths), which can be detectedhundreds of miles away from the ice. Thismechanism is currently being exploited by aNASA-sponsored mission called ANITA,which will use a high-altitude balloon tomonitor the radio pulses from about one million cubic kilometres of Antarctic ice.However, ANITA will be limited by thethermal noise and lack of transparency ofthe ice, which has a temperature of 240 K.

According to Gorham, the best way toovercome this problem is to use largebodies of ice in the solar system, such asEuropa, as detectors. About the size of theMoon, Europa is thought to be covered by athick layer of ice that has a temperature ofabout 90 K and penetrates to a depth oftens of kilometres or more. Gorham believesthat a satellite, or satellites, orbiting Europacould detect extremely high-energy cosmicneutrinos by picking up neutrino-inducedradio emissions from a much deepervolume of much colder ice than is availableon Earth.

IceCube principal investigator FrancisHalzen disagrees, however. “To calculatehow difficult it will be to develop such atelescope you just have to extrapolate theeffort and cost needed to build IceCube. I do not think it is something for mylifetime,” he says. But Halzen is careful notto rule out the concept altogether. “Mostpeople said we that we could never buildIceCube. But we are.”

Neutrino detectors in space

Cool stuff – the IceCube detector at the south polewill be used to detect cosmic neutrinos.


Cold fusion remains unproven but shouldnot be written off, according to a review ofthe disputed energy source carried out bythe US Department of Energy (DOE). Thereview concludes that although there is nofirm experimental evidence to support coldfusion – the generation of controlled nuc-lear fusion using just table-top devices –funding agencies should still consider sup-porting individual experiments in the field.

The report, issued last month, revives the controversy begun in 1987, when elec-trochemists Martin Fleischmann of theUniversity of Southampton in the UK andStanley Pons of the University of Utah inthe US reported that they had produceddeuterium–deuterium fusion by using a bat-tery connected to palladium electrodes inheavy water. Their subsequent announce-ment of the research at a press conference inMarch 1989 grabbed the world’s attention.The excess heat that they claimed to havegenerated in the experiment suggested anew type of energy source – one that wouldnot require the million-degree temperaturesneeded in conventional fusion. But the fail-ure of other scientists to replicate the resultsand a negative review of the technique car-ried out by the DOE discredited the work.

Despite this, a few scientists and engineershave continued to investigate cold fusion,and in late 2003 a group of researchers per-

suaded the DOE to take another look at theissue. The DOE sent a paper prepared byfour members of the group to nine reviewerswith backgrounds in experimental and the-oretical nuclear physics, materials science,and electrochemistry. Those reviewers andnine others, all of whom remain anony-mous, then spent a day questioning the fourauthors and other scientists involved in re-search on cold fusion.

The reviewers say they remain uncon-vinced about the reality of cold fusion, andbelieve that the field has been hampered bypoorly designed experiments and badly doc-umented results. But their verdict is notentirely negative: they think that the calori-meters used by cold-fusion researchers havebecome significantly more sophisticatedthan they were in 1989. Indeed, a third ofthe reviewers believe that the phenomenoncould potentially create excess power.

“Before the review the ratio of negative to positive feelings about cold fusion was100 or more to one,” says David Nagel, anengineer at George Washington Universityin Washington DC, and one of the groupwho submitted the paper to the DOE. “Butamong the reviewers, the ratio was more liketwo to one. So I cannot see anything butpositives in that.”Peter GwynneBoston, MA

Cold fusion gets luke-warm backingENERGY

P H Y S I C S W O R L D J A N U A R Y 2 0 0 58 p h y s i c s w e b . o r g

In late November last year, almost twomonths after the start of the US financialyear, Congress finally agreed on a budgetfor 2005. The budget was not good news for the National Science Foundation (NSF),which funds researchers at most USuniversities. It ended up with $5.47bn,some 1.9% less than it received in 2004.According to Kei Koizumi, a budget analystat the American Association for theAdvancement of Science, the reductiondestroys any chance of achieving the goal,agreed by both parties in Congress, ofdoubling NSF’s budget between 2002 and 2007.

In general, physics projects supported bythe NSF suffer uniform losses at about the1.9% level. But one significant newundertaking, the Rare Symmetry ViolatingProcesses (RSVP) project, which willexplore matter–antimatter asymmetry inthe universe, loses half of its proposedfunding. The project, construction on whichwas due to start later this year at theBrookhaven National Laboratory, will

receive $15m rather than the requested$30m. According to Koizumi, the reductionwill almost certainly delay the scheduledcompletion of the facility beyond 2007.

Other physics-related projects fare betterin the budget, however. Research oninertial-confinement fusion supported bythe Department of Energy receives $50mmore than requested by the Administration.NASA, meanwhile, wins an increase of 4.5%over its 2004 budget of $15.38bn, althoughthe American Physical Society hasexpressed concern that NASA’s scientificactivities might be reduced in order tosupport the agency’s proposed missions tothe Moon and Mars.Peter GwynneBoston, MA● President Bush has nominated chemicalengineer Samuel Bodman as EnergySecretary, replacing Spencer Abraham whoresigned in November shortly after theelection. Bodman, 66, has spent the pastfour years as a deputy secretary in the USCommerce and Treasury departments.

Congress destroys budget goalUS FUNDING

S IDEBANDSNASA seeks new boss…NASA was awaiting a new administratoras Physics World went to press following theresignation of Sean O’Keefe, who is acandidate to become the new president ofLouisiana State University. O’Keefe, whospent just three years at the helm ofNASA, would earn over $500 000 aspresident of the university, comparedwith just $158 000 as boss of the US spaceagency. He leaves several challenges forhis successor. The Space Shuttle remainsgrounded following the Columbia disaster,the International Space Station facesdelays, and the Bush administration’splans to send astronauts to the Moon andMars have been severely criticized. Mostimportantly, the new administrator mustcontinue O’Keefe’s efforts to change alackadaisical NASA culture that led to theloss of Columbia.

...and urged to send shuttle to HubbleAstronauts should be sent on the SpaceShuttle to service the Hubble SpaceTelescope, according to a panel set up bythe National Research Council (NRC).Led by Louis Lanzerotti – a physicistfrom the New Jersey Institute ofTechnology – the panel says that NASAshould organize a mission to fly toHubble as soon as the shuttle is clearedfor flight. This would be needed, thepanel says, to prevent the deterioration ofcomponents that could make thetelescope both unusable and impossibleto de-orbit safely. Given the quality ofscience that the telescope can continue toproduce 14 years after it was firstlaunched, a shuttle mission “is worth therisk”, according to Lanzerotti. OutgoingNASA boss Sean O’Keefe had said thetelescope should be repaired roboticallybecause it would be too dangerous to letastronauts do the job. He had previouslyargued it should not be serviced at all, butwas forced to change his mind followingan outcry from astronomers.

Caltech astronomers given new homeThe California Institute of Technology isto build a $50m facility that will bringtogether observational astronomers,theorists and instrument-makers underthe same roof. Caltech astronomerscurrently occupy four different buildings,which “from the intellectual point ofview leaves a lot to be desired”, says TomTombrello, chair of physics, mathematicsand astronomy. The Cahill Center forAstronomy and Astrophysics, which ismainly funded by the philanthropistCharles Cahill, will be complete by thisspring and will house about 100 staff.


P H Y S I C S W O R L D J A N U A R Y 2 0 0 5 9p h y s i c s w e b . o r g

Physicists from six Scottish universities are tojoin forces to create the largest physics de-partment in the UK. They will form a singleentity known as the Scottish UniversitiesPhysics Alliance (SUPA) that will carry outjoint research projects and run a singlegraduate school. With over 200 full-time re-searchers and initial funding of over £14mfor the next four years, SUPA aims to makeScottish physics more competitive on the in-ternational stage. However, there was badnews in England last month: Newcastle Uni-versity is to stop teaching pure physics de-grees – ending a 130-year tradition – whileKeele University is to axe all physics researchapart from astrophysics (see below).

SUPA will bring together physicists fromEdinburgh, Glasgow, Heriot Watt, Paisley,St Andrews and Strathclyde universities. Itwill receive £6.9m from the Scottish HigherEducation Funding Council, £5.9m fromthe six universities, as well as £1.3m fromthe Office of Science and Technology fornew equipment. SUPA aims to make phy-sicists in Scotland play to their strengths,rather than compete with one another for

funds. It was also set up to encourage theScottish Executive to invest more in Scottishuniversities, which do not – unlike theircounterparts in England – charge studentstuition fees.

Physics research will initially focus on five key areas – astronomy and astrophysics,condensed matter and materials physics,nuclear and plasma physics, particle physics,and photonics. There are plans to recruit

four new chairs as well as 16 lecturers, whowill be the “rising stars” of the future. A fur-ther 14 advanced fellowships will be given topromising young researchers. Although allstaff will be employed by the university atwhich they are based, they will be recruitedcentrally. Eight PhD prize studentships willalso be offered every year.

“We have worked for about 18 months on this plan and I am delighted to see it cometo fruition,” says Alan Miller, vice principalfor research at St Andrews. “SUPA sends amessage that Scotland has a strong sciencebase and a faith in the importance of physics.Planning the alliance has developed a verypositive synergy between the universities.”

John Chapman, head of physics and as-tronomy at Glasgow, adds that most physi-cists support the plan. “The staff are keenand I think SUPA will succeed,” he says.“We will also look to move into new researchareas as time goes by as we do not simplywant to freeze in whatever pattern was rightin 2004.”Matin Durrani● www.supa.ac.uk

Scottish physicists form a superteam…UK UNIVERS IT IES

Critical mass – physicists at Glasgow (above) andthe rest of Scotland will work together.

Physics has been placed on a list of subjectsof “national strategic importance” by theoutgoing education secretary CharlesClarke. He drew up the list shortly afterExeter University announced that it willclose its chemistry department due to a lackof money and just as Newcastle Universityrevealed that it will no longer offer degreesin pure physics. Clarke has asked the HigherEducation Funding Council for England for advice on how to protect subjects on thelist, which also includes other sciences, en-gineering and languages.

Newcastle’s decision was made after theuniversity carried out a review to “build onits strengths” in physics. Although all ex-isting physics students will be allowed tocomplete their degrees at Newcastle, no newstudents will be admitted from next autumn.The university currently has 35 first-yearphysics undergraduates, the last of whom is due to graduate in 2008.

The university will, however, launch a newmaster’s degree in computational physicslater this year as well as an interdisciplinary“natural sciences” degree in 2006. It is alsoconsidering strengthening nanotechnologyand materials science, which, it says, “aremore attractive to students and have greaterpotential for generating research income”.

Malcolm Young, pro vice-chancellor for

science at Newcastle, claims to be “delightedat the progress” the university is making. “Itis essential that we move with the times in thesciences,” he says. “I believe we will emergewith a much stronger portfolio of physicsand chemistry teaching and research pro-grammes that will be more relevant to theworld we live in today.”

However, Albert Crowe, head of physicsat Newcastle, calls the decision “unfor-tunate” and says that the university had fil-led its places in physics relatively easily. Hewas, however, relieved that none of the de-partment’s seven staff will lose their jobs.Ironically, the news emerged a day afterNewcastle was awarded “science city” sta-tus by the Chancellor Gordon Brown. It willshare £100m with Manchester and York toboost science research in the three cities.

According to Crowe, the decision to stopteaching physics is linked to the fact thatNewcastle only got a grade 4 for its physicsresearch in the 2001 Research AssessmentExercise (RAE). Since then the governmenthas cut funding for 4-rated departments,and focused it on those rated 5 or 5*.

“The vice chancellor [Christopher Ed-wards] feels that we will not be able to im-prove any further unless the universitymakes a major investment in physics, whichit is not prepared to do,” says Crowe. “He

thinks the only way we will do any better –without investing in new staff – is if we donot have to teach a full physics degree.” Aplan to move Newcastle’s physicists to Dur-ham fell through last year.

The theoretical physicist and best-sellingauthor Paul Davies says he is “saddened butnot shocked” at Newcastle’s decision to dropits undergraduate physics degree. Davies leftNewcastle in 1990 for a research position inAustralia after becoming disillusioned withphysics in Britain. Ironically, before he left,Davies had led negotiations to merge thephysics departments at Newcastle and Dur-ham. “In the end the plan was vetoed,” hesays. “There is a lesson for all physics depart-ments: it really is a case of ‘divided we fall’.”Matin Durrani● Keele University is to wind down all phy-sics research, apart from astrophysics. Thephysics department, which received a grade3a in the last RAE, currently has 14.5 full-time staff, nine of whom work on nuclearphysics, polymers, lasers and theory, and therest in astrophysics. Although Keele has noplans to sack any staff, a senior physicist atthe university says staff are “very worried”about their futures. And although Keele’sdual-honours degrees in physics or astro-physics with a second subject have beensaved, they will be now taught by fewer staff.

…while Newcastle axes pure physicsG

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Ever since it was established in 1943, theLos Alamos National Laboratory in NewMexico has been managed by the Univer-sity of California. Initially home to theManhattan atomic-bomb project, the lab isnow responsible for ensuring the safety andreliability of America’s stockpile of nuclearweapons, as well as carrying out a widerange of research in physics and related dis-ciplines. With some 13 600 employees andan annual budget of $2.1bn, it is a presti-gious and lucrative asset to the university.

But from October this year the lab may bein new hands. An embarrassing series of se-curity and safety lapses has hit Los Alamosin the past five years, leading to shutdowns,firings and other interruptions. These lapsespersuaded officials at the Department ofEnergy, which funds the national-laboratorysystem, to put the contract to manage LosAlamos out to tender. Although the Uni-versity of California can still bid for thiscontract, other universities and industrialcompanies are keen to take over.

Troubled timesThe recent controversies at Los Alamosstarted in 1999, when a physicist at the lab,Taiwan-born Wen Ho Lee, was accused bythe US government of leaking secret infor-mation on nuclear weapons and radar tech-nology to China. This accusation quicklyproved to be an embarrassing overreaction;Lee eventually pleaded guilty to a singlecharge of downloading classified materialonto a non-secure computer. But other in-cidents soon followed. In 2000 two harddrives from the lab containing highly clas-sified information were lost for four daysbefore being found in an area that had beenpreviously searched. And in late 2002 alle-gations of fraud, theft and the mismanage-ment of supplies led to several employeesbeing dismissed and the lab’s top two secur-ity officials being reassigned to other dutieswithin the lab. More importantly, the inci-dents resulted in the lab’s director, JohnBrowne, resigning and being replaced byPeter Nanos, a retired admiral with a PhDin physics and extensive experience in man-aging military laboratories.

But the security problems continued, cul-minating in a series of incidents last July. Inone, a lawyer at Los Alamos sent a classifiede-mail message from his unclassified homecomputer. In another, an accident in a laserexperiment burned a 0.5mm hole in the ret-ina of an undergraduate intern, damagingher vision. A subsequent investigation deter-mined that the student and her supervisor,

David Cremers, were not wearing protectivegoggles and had ignored other safety rules.In response, Nanos fired Cremers and triedto persuade other scientists involved with thelaser programme to resign. Cremers hassince appealed against his dismissal.

The incident that really created a stir,however, involved the apparent loss of twostorage drives containing classified informa-tion on an experiment in weapons physics.In an effort to renew confidence in the insti-tution and to “exercise control over our owndestiny”, Nanos sacked four employees,suspended 19 others, put a temporary haltto all classified work at the lab, and thensuspended almost all the lab’s activities sothat staff could review their security proce-dures. He reportedly described employeesat the lab as being in “suicidal denial” andas propagating a “culture of arrogance”.Commenting soon after the incident in July,Joe Barton, Republican Congressmen forTexas, said he thought that there is “prob-ably better security at the public library overCDs and videos”.

Further investigation provided strong evi-dence that the missing drives had never infact existed, and that their apparent disap-pearance was due to a book-keeping error.Nevertheless, Nanos continued to shake upthe lab’s management, splitting its opera-tions directorate in two in order to put moreemphasis on security. He also appointedDon Cobb, associate director for threat re-duction at Los Alamos, as acting deputylaboratory director.

Most of the lab’s activities have returnedto normal, although 10 of the 19 highestsecurity projects at the lab – most of them in the dynamic-experimentation division,which deals with the simulation of nuclear-weapons testing – remain in limbo. A labspokesperson indicates that even those pro-jects should be running again “fairly soon”.

Putting the house in orderIt now remains for the University of Califor-nia to show that it can clear up these prob-lems for good. Until now, the university hadreceived virtually automatic renewals of itscontract every five years. But last month theNational Nuclear Security Agency (NNSA),a semi-autonomous agency within the De-partment of Energy responsible for the nuc-lear stockpile, issued a preliminary requestfor proposals to manage the lab.

This document asks candidate organiza-tions to prove they can manage the lab’sresearch activities to a high standard. In ad-dition to “stockpile stewardship” these activ-ities range from particle and nuclear physicsto superconductors, quantum information,energy, the environment and medicine.Candidates will also need to demonstratetheir ability to manage the lab’s wider busi-ness operations. The winner of the biddingprocess will retain the lab’s current staff,apart from the director and the most seniormanagers, and, as an incentive, could haveits contract extended incrementally for up to15 years beyond the original five-year term.The NNSA expects to pick a winner beforethe end of the summer.

No bidders have yet been confirmed, butseveral organizations have shown an interest.These include the University of Texas, whichis spending $500000 to prepare its bid, andTexas A&M University. Other possible can-didates include aerospace giants LockheedMartin and Northrop Grumman, engineer-ing and services firm Fluor Corporation,consulting firm CSC, and the WashingtonGroup of BWX Technologies, which spe-cializes in managing nuclear operations.

After much soul-searching, it seems likelythat the University of California will try toretain its contract, possibly in collaborationwith an industrial partner. New Mexico gov-ernor Bill Richardson, who oversaw LosAlamos as President Clinton’s energy sec-retary, recently recommended that the uni-versity should apply to run the scientific sideof the contract, with a partner such as Lock-heed Martin, Northrop or the WashingtonGroup handling safety and security. “In myexperience, University of California man-agement is critical to the success of the lab,”said Richardson at a meeting of universitychiefs in December last year.

Whether the University of California canretain the contract remains to be seen, ofcourse. But no matter who wins the con-tract, they will face a major challenge inmaking sure that Los Alamos puts its secu-rity problems behind it.

Los Alamos looks to uncertain futureThe contract to run Los Alamos, the home of the atomic bomb, is up for grabs. Improvingsecurity will be a major challenge for the lab’s new managers, as Peter Gwynne reports


Is the writing on the wall for the University ofCalifornia’s management of Los Alamos?

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Cancer patients should soon benefit from animproved type of neutron therapy, thanks to a new agreement between US companyIsotron and the Oak Ridge National Labor-atory in Tennessee. Oak Ridge has licensed“neutron brachytherapy” to Isotron, a tech-nique that could help combat certain typesof prostate cancer, locally advanced breastcancer, cervical cancer, melanomas andbrain cancer. “Until now there has been notherapy for brain cancer,” says ManfredSandler, president of Isotron. “Our therapywill give patients with brain cancer a littlelonger to live with a decent quality of life.”

Neutron therapy is better at treating cer-tain cancers than the more widely used X-ray or proton therapy because neutronscan deposit a greater fraction of their en-ergy in the tumour, making it tougher fordamaged cancer cells to repair themselves.Brachytherapy involves placing a source ofradiation inside or near the tumour to targetthe cancer cells directly. In neutron brachy-therapy a source of californium-252, whichemits neutrons when it undergoes sponta-neous fission, is put through a hollow tube.

This technique has been available for a littleover 10 years, having been experimentedwith in the 1960s and 1970s.

Until now, however, the large wire-likesources used in neutron brachytherapy havenot only killed the cancerous cells but alsothe surrounding healthy cells. Researchersat Isotron and Oak Ridge have combatedthis by reducing the diameter of the tube

from 2.8 mm to a little over a millimetre. Soeven though the new source is over 10 timesstronger than its predecessor, it is also safer.The neutron-therapy machine has also beenmade safer for people operating it.

Assuming that Isotron gets the go-aheadfrom the US Food and Drugs Adminis-tration to start clinical trials, Sandler hopesto start licensing the company’s improvedinstrument out to treatment facilities from2007 onwards.

Meanwhile, the Fermi National Acceler-ator Laboratory near Chicago has restarteda neutron-therapy programme that had runfor 27 years and treated more than 3000cancer patients. The programme shut in2003 when a local hospital ended its involve-ment. Fermilab is now collaborating withNorthern Illinois University to form a newInstitute for Neutron Therapy that has se-cured $2.7m from the US government. Theinstitute – only the third site in the US tooffer the treatment for cancer patients –could open later this month.Querida AndersonNew York

New boosts for US neutron therapyMEDICAL PHYS ICS


Spot on – neutrons target cancer.

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www.nature.com

As the number one multidisciplinary science journal, Nature has long beenat the forefront in physics, publishing groundbreaking papers in all areas,from astrophysics and cosmology to applied physics and technology.

NATURE – CELEBRATING PHYSICS FOR 135 YEARS

Visit www.nature.com for more information and to subscribe

1897The

Zeemaneffect

1913The

nature ofisotopes

1932Discovery

of theneutron

1955Artificialdiamond

1973Invention

of MRI

1992Extrasolar

planets

1908A proposalfor television

1927Wavelike nature ofelectrons

1947Strangeparticles

1968Discovery ofpulsars

2004Quantumteleportation with atoms

1985Discovery ofC60


What would Albert Einstein think if he were alive today? As someone who dislikedthe limelight, he would probably be embarrassed by the celebrations that areplanned as part of the International Year of Physics to mark the centenary of hisremarkable achievements in 1905. As a theorist who was interested in experiments,in his early career at least, he would be pleased to know that a small band of 21st-century physicists are still trying to find flaws in the special theory of relativity, whileothers are busy checking out the predictions of the general theory. And havingspent the final years of his life trying to unify general relativity with electromagnet-ism, without success, he could be forgiven for thinking that criticisms of his relative

non-productivity in those years were somewhat un-fair. No-one else has succeeded where he failed.

It is impossible to overstate the importance ofwhat Einstein did in 1905. His work on Brownianmotion provided the theoretical framework forexperiments to prove that atoms were real. Hard asit might be to believe now, at the time the majorityof physicists did not believe in atoms. The specialtheory of relativity completely changed our notionsof space and time, while E = mc2 led to the remark-able conclusion that mass and energy are one andthe same. And his work on the photoelectric effectwas the start of a love–hate relationship with quan-tum mechanics that still fascinates physicists today.

And 1905 was just the beginning. The general theory of relativity – his truly out-standing achievement – followed 10 years later, with its predictions for the bendingof light by mass being confirmed a few years after that during the solar eclipse of1919. But even then Einstein did not abandon his interest in atoms, photons andquantum mechanics. The Einstein A and B coefficients for spontaneous and sti-mulated emission – without which we would not have lasers – made their debut in1916, and the prediction of Bose–Einstein condensation – one of the hottest topicsin experimental physics for the past decade – followed in the 1920s.

This special issue of Physics World covers all this and more. On page 19 MarkHaw describes Einstein’s theory of Brownian motion as a “slower, subtler revo-lution” than his work on relativity or quantum mechanics, but just as influentialnonetheless. On page 27 Clifford M Will provides an update on the renaissance inexperimental gravitational physics and reports how the general theory has so farsurvived all scrutiny, although it has not yet been tested in the strong-field limit.Most exciting, however, is the fact that theories that seek to unify gravity with thethree other fundamental forces of nature predict departures from general relativitythat will soon be within experimental reach.

Of course, the outstanding prediction of general relativity that has yet to beconfirmed is the existence of gravitational waves: on page 37 Jim Hough andSheila Rowan describe the almost superhuman efforts that are being made to findout if Einstein was right on this occasion. And as if to show that the great physicistcould also be wrong, on page 47 Harald Weinfurter reports on the state of the art in quantum entanglement – the phenomenon that Einstein once dismissed as“spooky action at a distance”. Other topics covered range from Einstein’s love ofmusic to the way his image is protected by the Hebrew University of Jerusalemand a Hollywood agent.

These articles are obviously preaching to the physics converted, but the organ-izers of the International Year of Physics – also known as World Year of Physicsand Einstein Year – have much loftier ambitions. Through a world-wide pro-gramme of events, demonstrations and other activities they hope to inspire thenext generation of physics students. Einstein would have approved.Peter Rodgers

Ahead of his time

The contents of this magazine, including the views expressed above, are the responsibility of the editor.They do not represent the views or policies of the Institute of Physics, except where explicitly stated.

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Copyright © 2005 by IOP Publishing Ltd and individualcontributors. All rights reserved. IOP Publishing Ltd permitssingle photocopying of single articles for private study orresearch, irrespective of where the copying is done. Multiplecopying of contents or parts thereof without permission is inbreach of copyright, except in the UK under the terms of theagreement between the CVCP and the CLA. Authorization ofphotocopy items for internal or personal use, or the internal orpersonal use of specific clients, is granted by IOP PublishingLtd for libraries and other users registered with the CopyrightClearance Center (CCC) Transactional Reporting Service,provided that the base fee of $2.50 per copy is paid directly toCCC, 27 Congress Street, Salem, MA 01970, USA

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Physics World has an ABC audited circulation for 2003 of 36 206


E I N S T E I N 2 0 0 5

P H Y S I C S W O R L D J A N U A R Y 2 0 0 514 p h y s i c s w e b . o r g

The early years1879 Born 14 March at Bahnhofstraße 135, Ulm, Germany1880 Einstein’s family moves to Munich, where his father founds afirm manufacturing electrical equipment1888 Enters Luitpold Gymnasium in Munich1894 Family moves to Italy; Albert stays in Munich, but gets de-pressed without his family and does not complete his schooling1895 Albert joins family in Italy; fails entrance exam for the ETHZurich; moves to Aarau, Switzerland1896 Obtains diploma from cantonal school in Aarau, which allowshim to enrol for the ETH Zurich; relinquishes German citizenship1900 Receives diploma from Zurich, scoring 5 (out of a possible 6)for theoretical physics, experimental physics and astronomy, and5.5 for theory of functions

Life after college1901 Becomes a Swiss citizen, but declared unfit for military ser-vice due to flat feet and varicose veins; gets a few temporary school-teaching jobs1902 Appointed technical expert (third class) at the patent office inBern with a salary of SwFr 3500; fiancée Mileva Marić – a fellowstudent from Zurich – gives birth to illegitimate daughter Lieserl1903 Marries Mileva on 6 January1904 First son, Hans Albert, born 14 May1905 Einstein’s annus mirabilis: submits PhD thesis on moleculardimensions to University of Zurich, as well as two papers on specialrelativity, one on quantum theory and another on Brownian motionto Annalen der Physik1906 Promoted to technical expert (second class), salary raised toSwFr 45001907 Einstein has “the happiest thought of my life” – that a gravi-tational field is equivalent to acceleration

Turning professional1909 Resigns from patent office and starts work as associate profes-sor at University of Zurich on 15 October1910 Second son, Eduard, born 28 July1911 Appointed full professor at the German University of Prague,where he works out that the bending of light should be detectableduring a solar eclipse; attends first Solvay Congress in Brussels1912 Returns to Switzerland as professor at the ETH Zurich1914 Becomes professor at the University of Berlin; moves into abachelor apartment after separating from Mileva, who returns withsons to Zurich1915 Completes theory of general relativity; co-signs an anti-warmanifesto urging people to join a “League of Europeans”1916 Writes 10 papers, including first paper on gravitational waves,

and one on the spontaneous and stimulated emission of light; pub-lishes The Origins of the General Theory of Relativity; succeeds MaxPlanck as president of the German Physical Society1917 Becomes founding director of Kaiser-Wilhelm Institut, Ber-lin; writes paper on the twin paradox; introduces the cosmologicalconstant; overwork triggers liver problem, stomach ulcer and jaun-dice that together confine him to bed for several months – lookedafter by his cousin Elsa Einstein Löwenthal

Public fame1919 Marries Elsa on 2 June; divorce settlement with Mileva stipu-lates that she would receive any Nobel-prize money from Einstein;eclipse watchers confirm his prediction that the Sun bends distantstarlight, leading to headlines around the world1920 Toys with leaving Germany after attacks on relativity byanti-semites1921 Visits the US for first time1922 Awarded 1921 Nobel Prize for Physics for his “services to the-oretical physics and in particular for his discovery of the law of thephotoelectric effect” – prize money of about $32 000 given to Mi-leva; completes first paper on unified field theory1924 Einstein Institute founded in Potsdam; predicts Bose–Einsteincondensation1927 Attends fifth Solvay Congress in Brussels and starts debate onquantum theory with Niels Bohr

Life in the US1933 Leaves Germany after Nazis take power and joins the Insti-tute for Advanced Study in Princeton – a “quaint and ceremoniousvillage of demigods on stilts”; rejects cosmological constant1935 Publishes strident attack on quantum theory with Boris Po-dolsky and Nathan Rosen1936 Elsa dies1939 Signs letter to President Roosevelt warning of dangers ofatomic bomb1940 Becomes US citizen, while retaining Swiss citizenship1944 Retires from Princeton, aged 65; writes out by hand his ori-ginal 1905 paper on special relativity for auction, raising $6m forUS war effort1946 Becomes chairman of the Emergency Committee of AtomicScientists; calls for world government to be formed1952 Turns down an offer to be President of Israel1955 Signs “Russell–Einstein manifesto” on 11 April urging nationsto renounce nuclear weapons; dies in Princeton at 1.10 a.m. on18April from ruptured abdominal aorta; brain removed by pathol-ogist Thomas Harvey; body cremated at the Ewing CrematoriumMatin Durrani

A brief history of Albert EinsteinBorn in Germany in 1879, Einstein became the most famous physicist the world has ever seen

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In his own words

Online informationAlbert Einstein Archivesjnul.huji.ac.il/einsteinAlbert Einstein: Image and Impact (online exhibit)www.aip.org/history/einsteinEinstein Papers Projectwww.einstein.caltech.eduEinstein Year: A Year Celebrating Physics (UK and Ireland)[email protected]/events/einsteinathome/index.htmlEinstein’s FBI filewww.theeinsteinfile.comWorld Year of Physicswww.wyp2005.orgWorld Year of Physics (US site)www.physics2005.org

Diary dates13–15 JanuaryPhysics for Tomorrow: Launch Conferenceof the International Year of PhysicsUNESCO, Pariswww.wyp2005.org/unesco17–21 FebruaryAAAS Annual Meeting: World Year of PhysicsWashington, DCwww.aaas.org/meetings/Annual_Meeting/02_PE/PE_07_SemD.shtml4–9 MarchPhysik seit EinsteinBerlinwww.dpg-physik.de/wyp200510–14 AprilPhysics, a century after EinsteinWarwick, UKwww.physics2005.iop.org11–15 JulyBeyond Einstein: Physics for the 21st CenturyBern, Switzerlandwww.eps13.org11–15 JulyLe Siècle d’Albert Einstein (for the public)Pariseinstein2005.obspm.fr/indexr.html18–22 JulyAlbert Einstein Century InternationalConferencePariseinstein2005.obspm.fr/indexr.html31 October–2 NovemberWorld Conference on Physics andSustainable DevelopmentDurban, South Africawww.saip.org.za/physics2005/WCPSD2005.html

Einstein resources and events

The supreme task of the physicist is to arrive at thoseuniversal elementary laws from which the cosmos can bebuilt up by pure deduction.The Expanded Quotable Einstein (Princeton University Press)

Master of the universe. Albert Einstein is probably the most famous person inhistory, and almost certainly the smartest. Many of the world’s greatest thinkerssought Einstein out during his lifetime – the photograph above was taken during a meeting with the Nobel-prize-winning Indian poet Rabindranth Tagore in 1930– and today, 50 years after his death, the father of relativity still captures the ima-gination of the world at large. Walk into a shop selling toys for children and youwill find “Baby Einstein” CDs and books. Ask for help in Microsoft Word and acartoon Einstein will do his best to solve your problem. To physicists and non-physicists alike, Einstein has become a byword for genius. This year the physicscommunity will celebrate the centenary of 1905 – the year that Einstein kick-started modern physics with his work on special relativity, Brownian motion andquantum mechanics – with a worldwide programme of events. Every month dur-ing 2005 Physics World will publish news of these events (see panel on left), togetherwith photographs and quotations from the original master of the universe.

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Most physicists would be happy to make one discovery that is important enough to betaught to future generations of physics stu-dents. Only a very small number managethis in their lifetime, and even fewer maketwo appearances in the textbooks. But Ein-stein was different. In little more than eightmonths in 1905 he completed five papersthat would change the world for ever. Span-ning three quite distinct topics – relativity,the photoelectric effect and Brownian mo-tion – Einstein overturned our view of spaceand time, showed that it is insufficient todescribe light purely as a wave, and laid thefoundations for the discovery of atoms.

Perhaps even more remarkably, Einstein’s1905 papers were based neither on hardexperimental evidence nor sophisticatedmathematics. Instead, he presented elegantarguments and conclusions based on phys-ical intuition. “Einstein’s work stands outnot because it was difficult but becausenobody at that time had been thinking theway he did,” says Gerard ’t Hooft of theUniversity of Utrecht, who shared the 1999Nobel Prize for Physics for his work in quan-tum theory. “Dirac, Fermi, Feynman andothers also made multiple contributions tophysics, but Einstein made the world realize,for the first time, that pure thought canchange our understanding of nature.”

And just in case the enormity of Ein-stein’s achievement is in any doubt, we haveto remember that he did all of this in his“spare time”.

Statistical revelationsIn 1905 Einstein was married with a one-year-old son and working as a patent exam-iner in Bern in Switzerland. His passion wasphysics, but he had been unable to find anacademic position after graduating from theETH in Zurich in 1900. Nevertheless, hehad managed to publish five papers in theleading German journal Annalen der Physikbetween 1900 and 1904, and had also sub-mitted an unsolicited thesis on molecularforces to the University of Zurich, whichwas rejected.

Most of these early papers were con-cerned with the reality of atoms and mole-cules, something that was far from certain at the time. But on 17 March in 1905 – threedays after his 26th birthday – Einstein sub-mitted a paper titled “A heuristic point ofview concerning the production and trans-formation of light” to Annalen der Physik.

Einstein suggested that, from a thermo-dynamic perspective, light can be describedas if it consists of independent quanta of

energy (Ann. Phys., Lpz 17 132–148). Thishypothesis, which had been tentatively pro-posed by Max Planck a few years earlier, di-rectly challenged the deeply ingrained wavepicture of light. However, Einstein was ableto use the idea to explain certain puzzles

about the way that light or other electro-magnetic radiation ejected electrons from ametal via the photoelectric effect.

Maxwell’s electrodynamics could not, forexample, explain why the energy of theejected photoelectrons depended only onthe frequency of the incident light and noton the intensity. However, this phenomenonwas easy to understand if light of a certainfrequency actually consisted of discretepackets or photons all with the same energy.Einstein would go on to receive the 1921Nobel Prize for Physics for this work, al-though the official citation stated that theprize was also awarded “for his services totheoretical physics”.

“The arguments Einstein used in the pho-toelectric and subsequent radiation theory

are staggering in their boldness and beauty,”says Frank Wilczek, a theorist at the Massa-chusetts Institute of Technology who sharedthe 2004 Nobel Prize for Physics. “He putforward revolutionary ideas that both in-spired decisive experimental work andhelped launch quantum theory.” Althoughnot fully appreciated at the time, Einstein’swork on the quantum nature of light wasthe first step towards establishing the wave–particle duality of quantum particles.

On 30 April, one month before his paperon the photoelectric effect appeared inprint, Einstein completed his second 1905paper, in which he showed how to calculateAvogadro’s number and the size of mole-cules by studying their motion in a solution.This article was accepted as a doctoral thesisby the University of Zurich in July, and pub-lished in a slightly altered form in Annalen derPhysik in January 1906. Despite often beingobscured by the fame of his papers on spe-cial relativity and the photoelectric effect,Einstein’s thesis on molecular dimensionsbecame one of his most quoted works. In-deed, it was his preoccupation with statis-tical mechanics that formed the basis ofseveral of his breakthroughs, including theidea that light was quantized.

After finishing a doctoral thesis, mostphysicists would be either celebrating orsleeping. But just 11 days later Einstein sent

another paper to Annalen der Physik, this timeon the subject of Brownian motion. In thispaper, “On the movement of small particlessuspended in stationary liquids required bythe molecular-kinetic theory of heat”, Ein-stein combined kinetic theory and classicalhydrodynamics to derive an equation thatshowed that the displacement of Brownianparticles varies as the square root of time(Ann. Phys., Lpz 17 549–560).

This was confirmed experimentally byJean Perrin three years later, proving onceand for all that atoms do exist (see “Ein-stein’s random walk” on page 19). In fact,Einstein extended his theory of Brownianmotion in an additional paper that he sent tothe journal on 19 December, although thiswas not published until February 1906.

Five papers that shook the worldIn 1905 an anonymous patent clerk in Bern rewrote the laws of physics in his spare time.Matthew Chalmers describes Einstein’s miraculous year


Genius at work – Einstein was just 26 when hemade three ground-breaking contributions tophysics in a single year. Here he is pictured at theSwiss patent office in early 1906.

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“The arguments Einsteinused were staggering intheir boldness and beauty.”

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A special discoveryShortly after finishing his paper on Brown-ian motion Einstein had an idea aboutsynchronizing clocks that were spatially sep-arated. This led him to write a paper thatlanded on the desks of Annalen der Physik on30 June, and would go on to completelyoverhaul our understanding of space andtime. Some 30 pages long and containing no references, his fourth 1905 paper wastitled “On the electrodynamics of movingbodies” (Ann. Phys., Lpz 17 891–921).

In the 200 or so years before 1905, phy-sics had been built on Newton’s laws ofmotion, which were known to hold equallywell in stationary reference frames and inframes moving at a constant velocity in astraight line. Provided the correct “Gali-lean” rules were applied, one could there-fore transform the laws of physics so thatthey did not depend on the frame of ref-erence. However, the theory of electrody-namics developed by Maxwell in the late19th century posed a fundamental problemto this “principle of relativity” because itsuggested that electromagnetic waves al-ways travel at the same speed.

Either electrodynamics was wrong orthere had to be some kind of stationary“ether” through which the waves could pro-pagate. Alternatively, Newton was wrong.True to style, Einstein swept away the con-cept of the ether (which, in any case, had notbeen detected experimentally) in one au-dacious step. He postulated that no matterhow fast you are moving, light will alwaysappear to travel at the same velocity: thespeed of light is a fundamental constant ofnature that cannot be exceeded.

Combined with the requirement that thelaws of physics are the identical in all “iner-tial” (i.e. non-accelerating) frames, Einsteinbuilt a completely new theory of motionthat revealed Newtonian mechanics to bean approximation that only holds at low,everyday speeds. The theory later becameknown as the special theory of relativity –special because it applies only to non-accel-erating frames – and led to the realizationthat space and time are intimately linked toone another.

In order that the two postulates of specialrelativity are respected, strange things haveto happen to space and time, which, unbe-known to Einstein, had been predicted byLorentz and others the previous year. Forinstance, the length of an object becomesshorter when it travels at a constant velocity,and a moving clock runs slower than a sta-tionary clock. Effects like these have beenverified in countless experiments over the last100 years, but in 1905 the most famous pre-diction of Einstein’s theory was still to come.

After a short family holiday in Serbia, Ein-stein submitted his fifth and final paper of1905 on 27 September. Just three pages longand titled “Does the inertia of a body dependon its energy content?”, this paper presented

an “afterthought” on the consequences ofspecial relativity, which culminated in a sim-ple equation that is now known as E=mc2(Ann. Phys., Lpz 18 639–641). This equation,which was to become the most famous in all of science, was the icing on the cake.

“The special theory of relativity, cul-minating in the prediction that mass andenergy can be converted into one another,is one of the greatest achievements in phy-sics – or anything else for that matter,” saysWilczek. “Einstein’s work on Brownian mo-tion would have merited a sound Nobelprize, the photoelectric effect a strong Nobelprize, but special relativity and E = mc2 wereworth a super-strong Nobel prize.”

However, while not doubting the scale ofEinstein’s achievements, many physicists alsothink that his 1905 discoveries would haveeventually been made by others. “If Einsteinhad not lived, people would have stumbledon for a number of years, maybe a decade or so, before getting a clear conception ofspecial relativity,” says Ed Witten of the In-stitute for Advanced Study in Princeton.

’t Hooft agrees. “The more natural courseof events would have been that Einstein’s1905 discoveries were made by differentpeople, not by one and the same person,” hesays. However, most think that it would havetaken much longer – perhaps a few decades– for Einstein’s general theory of relativity to emerge. Indeed, Wilczek points out thatone consequence of general relativity beingso far ahead of its time was that the subjectlanguished for many years afterwards.

The aftermathBy the end of 1905 Einstein was starting to make a name for himself in the physicscommunity, with Planck and Philipp Lenard– who won the Nobel prize that year –among his most famous supporters. Indeed,Planck was a member of the editorial boardof Annalen der Physik at the time.

Einstein was finally given the title of HerrDoktor from the University of Zurich inJanuary 1906, but he remained at the patentoffice for a further two and a half years be-fore taking up his first academic position atZurich. By this time his statistical interpret-ation of Brownian motion and his bold pos-tulates of special relativity were becomingpart of the fabric of physics, although itwould take several more years for his paperon light quanta to gain wide acceptance.

1905 was undoubtedly a great year forphysics, and for Einstein. “You have to goback to quasi-mythical figures like Galileo orespecially Newton to find good analogues,”says Wilczek. “The closest in modern timesmight be Dirac, who, if magnetic mono-poles had been discovered, would havegiven Einstein some real competition!” Butwe should not forget that 1905 was just thebeginning of Einstein’s legacy. His crowningachievement – the general theory of relativ-ity – was still to come.


Einstein’s annus mirabilis tends toovershadow other scientific developmentsthat took place in 1905. So what else wasgoing on in the year that cellophane wasinvented, the neon sign made its debut, andpeople were getting to grips with tea bagsfor the first time? In terms of the number ofcitations in physics and physical-chemistryjournals since 1945, three of Einstein’s1905 papers feature in the top five,according to Werner Marx and ManuelCardona of the Max Planck Institute for Solid State Research in Stuttgart. Indeed,his papers on Brownian motion and specialrelativity take first and second place,respectively, with 1467 and 642 citations(his papers on the photoelectric effect andE = mc2 are fifth and 11th). The fourth most-cited paper of 1905 was by Paul Langevin,who derived a fundamental formula inkinetic theory – clearly a popular subject atthe time – while Lawrence Bragg publisheda paper about the energy loss of alphaparticles in different media, which becamethe sixth most-cited paper of the year.

Hendrik Antoon Lorentz, who wasinfluential in the development of specialrelativity, was elected as a fellow of the Royal Society in 1905 and published severalpapers, including one on the motion ofelectrons in metallic bodies. Nuclear physicswas also a subject of intense interest at thetime, with Ernest Rutherford and FrederickSoddy publishing their theory of nucleartransmutation and Bertram Boltwooddemonstrating that lead is the final productof uranium decay. Further afield, VictorGoldschmidt introduced a method to reducemetallic oxides to metals, while Haldane andPriestley demonstrated the role of carbondioxide in the regulation of breathing.

Outside the world of science, anunsuccessful revolution was beginning inRussia, Antonio Gaudi began two of hisfamous buildings in Barcelona, and H G Wells had written Kipps. Meanwhile,Jean-Paul Sartre and Henry Fonda wereborn, as was the Nobel-prize-winningphysicist Emilio Segrè, who 40 years laterwould witness the application of E=mc2 withthe detonation of the first atomic bomb. MC

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MOST OF US probably remember hear-ing about Brownian motion in highschool, when we are taught that pollengrains jiggle around randomly in waterdue the impacts of millions of invisiblemolecules. But how many people knowabout Einstein’s work on Brownianmotion, which allowed Jean Perrin andothers to prove the physical reality ofmolecules and atoms?

Einstein’s analysis was presented in a series of publications, including hisdoctoral thesis, that started in 1905 witha paper in the journal Annalen der Physik.Einstein’s theory demonstrated howBrownian motion offered experimen-talists the possibility to prove that mo-lecules existed, despite the fact thatmolecules themselves were too small to be seen directly.

Brownian motion was one of threefundamental advances that Einsteinmade in 1905, the others being specialrelativity and the idea of light quanta(see “Five papers that shook the world”on page 16). Of these three great works, Einstein’s analysis of Brownian motion remains the least well known. But thispart of Einstein’s scientific legacy was the key to a revolutionthat is at least as important as relativity or quantum physics.One century later, Brownian motion continues to be of im-measurable importance in modern science, from physicsthrough biology to the latest wonders of nanotechnology.Indeed, this is reflected in citation statistics, which show thatEinstein’s papers on Brownian motion have been cited manymore times than his publications on special relativity or thephotoelectric effect.

The story of Brownian motion spans almost two centuries,its unlikely roots lying in a scientific craze that swept westernEurope at the beginning of the 1800s. And it starts, surpri-singly enough, not with a physicist but with a botanist.

Brown’s botanyIn the early 19th-century Europeans became fascinated bybotany. In Britain this interest was fuelled by explorations tothe corners of the growing empire, particularly Australia or“New Holland” as it was known at that time. One of the first

people to get their botanical teeth into New Holland was Rob-ert Brown, who had grown up botanizing in the Scottish hills.

After completing a medical degree at Edinburgh Universityand a brief period in the army, during which he spent most ofhis time specimen-hunting around Ireland, Brown secured aplace as ship’s botanist on a surveying mission to Australia in1801. Risking attack from Napoleon’s fleets, Brown spent fouryears exploring the Australian and Tasmanian coasts beforereturning to London laden with thousands of specimens ofnew species, his reputation as one of Europe’s leading botan-ists already secure.

But Brown was interested in more than collecting and cata-loguing different species – he was also a pioneer of botany asa scientific investigation. Indeed, he is credited with the firstclear description of the cell nucleus, and it was Brown thatCharles Darwin came to for advice before setting out in theBeagle in 1831. In fact, the botanical craze in which Brownhad played a major part laid the vital groundwork for

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