2 what is science?
DESCRIPTION
Big Questions in Science series, (2 of 9). Class taught at AUC (University of Amsterdam) during the 2012-2013 fall semester.TRANSCRIPT
Physics, Astronomy, Chemistry
Sebastian de Haro, fall 2012
Big Questions in Science, spring 2012. SdH, AUC 2
3a, 3b Time and relativity
5b Chemistry
4b, 5a Quantum mechanics
4a Our cosmic origins
1b Classical physics
Big Questions in Science, fall 2012. SdH, AUC 2
Class discussion:
List some of the essential properties of science as an academic activity (also properties that distinguish it from other activities).
Big Questions in Science, fall 2012. SdH, AUC 3
The following elements will have appeared in your definitions of science discussed in class:
Logic, rigor.
Scientific method.
Falsifiability .
Experimental verifiability.
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One goal of the course is to demystify some of the ideas about science that you may find in popular books or media:
Science is messy, with lots of guesswork, serendipity.
Theories are not falsified by one single observation.
Scientific products are presented in the strictly logical, rigorous way. But the actual scientific process (including research and scientific discussions) is usually rather different.
Big Questions in Science, fall 2012. SdH, AUC 5
Four generic properties I would like to emphasize, in addition to the ones already mentioned:
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Big Questions in Science, fall 2012. SdH, AUC 7 http://www.umsl.edu/~fraundorfp/stm97x.html http://ebooks.adelaide.edu.au/h/hooke/robert/micrographia/plates/scheme34.png
http://outreach.atnf.csiro.au/
http://inhabitat.com/new-mars-curiosity-science-laboratory-will-be-nuclear-powered-not-solar-powered/
Other important driving forces:
economic interests, technological
advance, societal and political needs,…
Key driving force behind scientific research:
human curiosity. We want to know what
nature around us looks like, both in the
worlds of the smallest, of the largest, and in
the intermediate scale of complexity.
Big Questions in Science, fall 2012. SdH, AUC 8 http://en.wikipedia.org/wiki/Las_Meninas http://www.blogmuseupicassobcn.org/2009/06/weve-got-something-special-to-celebrate-a-brand-new-addition-to-the-museu-picasso/?lang=en
If artists represent (or interpret) aspects of reality that usually cannot be grasped by
analytic means, scientists aim to represent its objective, quantitative features. Both
artists and scientists need lots of creativity!
The scientific enterprise requires abstraction from reality: retaining the aspects that
are relevant to a particular question or research, searching for universal patterns,
laws, and principles that can be reproduced and tested.
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http://science.nasa.gov/science-news/science-at-nasa/2004/13jul_solarblast/
Experiment and observation. Experiments allow scientists
to test their hypotheses or gather new information about
nature in a controlled setting. Changing the experimental
conditions allows to establish or disprove causal links.
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“Traditionally these are questions for philosophy,
but philosophy is dead. Philosophy has not
kept up with modern developments in
science, particularly physics. Scientists have
become the bearers of the torch of discovery
in our quest for knowledge. The purpose of
this book is to give the answers that are
suggested by recent discoveries and theoretical
advances. They lead us to a new picture of the
universe and our place in it that is very different
from the traditional one, and different even from
the picture we might have painted just a decade
or two ago. Still, the first sketches of the new
concept can be traced back almost a century.”
(The Grand Design).
Big Questions in Science, fall 2012. SdH, AUC
Science and philosophy:
a love-hate relationship
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Method does not guarantee full truth or even empirical adequacy.
Dogmatism about ‘method’ can kill creativity:
Rutehrford wouldn’t let Bohr publish his result.
Bohr wouldn’t Heisenberg publish his result.
Heisenberg said the Higgs was not the way the world works.
Methodologies change. Look at actual examples!
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Presu
pp
ositio
ns
Mathematics Logic
Axioms
Model
Presuppositions (ethical, epistemic, ontological)
Reality
Future reality
Past reality
Observation
Experiment
Technology
Big Questions in Science, fall 2012. SdH, AUC
• Science aims at representing reality in a model that allows to
explain the present and predict the future (retrodict or understand
the past). Technology, experiment, and observation play an
important role in connecting models with reality.
• The model itself rests on experimental data, a number of specific
axioms, as well as a broader set of assumptions. The particular
logic employed depends on the particular field.
Big Questions in Science, fall 2012. SdH, AUC 15
A brief history of the universe
http://planck.cf.ac.uk/science/timeline/universe
Turning points in the
history of the universe
organized around the
universe’s timeline.
Main era’s in the
evolution of the
universe.
Documentary film Powers of Ten (9 min)
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In groups of two: go to http://htwins.net/scale2 and look up, for ten different length scales (
, etc.), ten corresponding items in
the universe. Go also to the negative powers! Pay particular attention to earth science & biology.
Switch off the sound! We will make a (linear) map of the universe. You can cross-check your data with estimates
that you find on the internet. Big Questions in Science, fall 2012. SdH, AUC 17
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Metric prefixes
Prefix Symbol 1000m 10n Decimal Short scale Long scale Since[n 1]
yotta Y 10008 1024 1000000000000000
000000000 septillion quadrillion 1991
zetta Z 10007 1021 1000000000000000
000000 sextillion trilliard 1991
exa E 10006 1018 1000000000000000
000 quintillion trillion 1975
peta P 10005 1015 1000000000000000 quadrillion billiard 1975
tera T 10004 1012 1000000000000 trillion billion 1960
giga G 10003 109 1000000000 billion milliard 1960
mega M 10002 106 1000000 million 1960
kilo k 10001 103 1000 thousand 1795
hecto h 10002/3 102 100 hundred 1795
deca da 10001/3 101 10 ten 1795
10000 100 1 one –
deci d 1000−1/3 10−1 0.1 tenth 1795
centi c 1000−2/3 10−2 0.01 hundredth 1795
milli m 1000−1 10−3 0.001 thousandth 1795
micro μ 1000−2 10−6 0.000001 millionth 1960
nano n 1000−3 10−9 0.000000001 billionth milliardth 1960
pico p 1000−4 10−12 0.000000000001 trillionth billionth 1960
femto f 1000−5 10−15 0.000000000000001 quadrillionth billiardth 1964
atto a 1000−6 10−18 0.000000000000000001
quintillionth trillionth 1964
zepto z 1000−7 10−21 0.000000000000000000001
sextillionth trilliardth 1991
yocto y 1000−8 10−24 0.000000000000000000000001
septillionth quadrillionth 1991 Big Questions in Science, fall 2012. SdH, AUC
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The Big Questions Connecting Circle
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Different length scales
distributed on the Big
Questions Connecting
Circle.
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Examples of scientific theories distributed on
the Big Questions Connecting Circle.
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Examples of sciences distributed on the
Big Questions Connecting Circle.
Presocratic science: study of matter and astronomy
Atomism and Plato’s Timaeus: mathematics Greek science: First Theories of Everything
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Thales: water, predicted solar eclipse.
Anaximander: apeiron,
Earth cylindrical, suspended in void.
Anaximenes: air (rarefaction,
condensation).
Heraclitus: fire
Empedocles: four elements
Democritus and Leucippus: atoms,
Flat earth.
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585 BC Thales
of Miletus
Time and length scales Great adventure: curiosity Abstraction Methods:question, observation, knowledge,
innovation From mythos to logos Greek science: matter, geometry.
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Theaetetus via Plato and Euclides: the five Platonic solids
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Cube (rectangle) Tetrahedron, octahedron, icosahedron
(equilateral triangles)
No
!
Set minimal length to 1.
Use Pythagoras theorem
other lengths follow
The numbers (1,2,3) are given by musical octave and fifth. Generate the Dorian musical scale:
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1:2 octave
2:3 perfect fifth
3:4 perfect fourth
4:5 major third
5:6 minor third
6 8 9 12
1 2
D E F# G A B C# D
4/3
3/2 arithmetic mean
harmonic mean
Properties of elementary triangles linked with harmonies of music.
Platonic solids built up of such triangles. Properties of triangles give properties of solids and will ‘explain’ properties of matter.
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Big Questions in Science, fall 2012. SdH, AUC 31
Earth Fire Air Water
Symmetry among
these three: all share
same elementary
triangles
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Earth Fire Air Water
rarification, condensation
evaporation
condensation
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Largest volume when inscribed in sphere. Contains other Platonic solids.
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Numbers as universal language, at the root of all natural processes.
Symmetry leads to ‘conserved quantities’:
Stable earth: isosceles triangle symmetric.
Interchangeability fire, air, water.
Link between numbers, physiology, and arts: quantity and quality.
Adds concept of ‘measure’, ‘form’ to Ionian/atomistic ideas.
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Although speculative, basic principle is a chemistry of four elements.
Reactions explained from mathematical combinations allowed by geometry.
Problem of ‘asymmetry’ always present: ‘likely account’. Hypothesis open to critique.
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“Our illustrator of the atomic model [in a school text-book of physics] would have done well to make a careful study of Plato before producing his particular illustration” (Heisenberg, cited by Guthrie).
Heisenberg first thought about atoms while reading Plato’s Timaeus.
Pythagoras highly influential at dawn of two scientific revolutions: Kepler and Sommerfeld.
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Rational explanation Logic, argumentation Empirical (though not ‘experimental’) Universe finite and knowable Important factors:
Development of culture
Overseas trading, different civilizations
Openness to intellectual innovation
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Periodic table: classification scheme of the chemical elements based on simple physical principles.
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Physical forces: seemingly distinct forces can be reduced to simpler forces and mathematical principles.