Download - Basic Natural Science
OverviewBasic of Natural Science
Tony K. Hariadi
Today’s Lecture
• Course overview• What is science?• Science and truth• Math in Nature• Science and Beauty• The Big Ideas
Why are you here?
• Science is important.– Significant human intellectual
achievement– Deals with fundamental questions– Provides answers– Leads to technology– Solves problems– Social issues center around science
Scientific Social Issues
• Extermination of species• Organ transplants• Cloning• Nuclear power and weapons• Overpopulation• Use of outer space• Global warming• Ozone depletion
What is the course all about?
The “story of stuff”
What is the Universe like?What is our place in the cosmos?What is our origin?How did the Universe evolve?
What is Science?
“Science is the marriage of skepticism and wonder.”
Carl Sagan
Science is a method
• Hypothesis—create beautiful theories to explain and unify natural phenomena
• Prediction—apply theory to new regime• Experiment—use objective observations of Nature to
decide the truth
The Scientific Method
The Faith behind Science
• The Universe is built on a foundation of order.
• The Universe is explicable.• The Universe is mathematical.• Nature operates with a few simple
laws.• These laws have the same rules
everywhere.
Science and truthScience provides a quantitative
description of Nature.Science is only as good as its
predictions!Can only describe reality within
the limits of the human mind.Even the best theories may not
be (completely) true!Science may never arrive at
truth.
And yet…
Some ideas work so well they seem indistinguishable from truth:– Atoms– Gravity
Why does it work?
• Empiricism: go to Nature for answers
• Reject bad theories.
“The great tragedy of Nature is the murder of beautiful theories by ugly fact.” Mark Twain
Is the Universe mathematical?“It is Nature herself, and not the
mathematician, who brings mathematics into natural philosophy.”
Kant
Math in Nature
• Does math form the fundamental basis for everything?
• Math revealed in nature– LAWS– FORMS
Crystals
Ice: hexagonal symmetry
SymmetryIn mathematics, “symmetry’’ refers to an operation that leaves an object unchanged.
Reflect through a mirror
Rotate by 90o
Ice
Edward
Weston
What about life?• Many creatures have mathematical
shapes• Many creatures exhibit symmetries
– Bilateral– Rotational
Mathematical Forms in Life
Equiangular Spiral
0/0eRR
Edward WestonThe Chambered Nautilus
Nautilus Shell
A perfect logarithmic spiral!
More Equiangular Spirals
More spirals
Bilateral Symmetry
Bilaterally Symmetric Life
Bilaterally Symmetric Life
Edward Weston
Bilaterally Symmetric Life
Edward Weston
Bilaterally Symmetric Life
Edward
Weston
Rotational Symmetry
Rotationally Symmetric Life
Rotationally Symmetric Life
Rotationally Symmetric Life
Rotationally Symmetric Life
Rotationally Symmetric Life
Mushroom Gills
Mushrooms
Gill spacing never
too large
Fractals in nature• Fractals are objects that look the
same regardless of the magnification.• “Scale-invariant”
Fractals
River drainage
More fractals
More fractals
More fractals
Fractal Life
Fractal Life
Fractal Life
Fractal Life
Fractal Life
Examples of fractals in nature• Trees• Lungs• Viscous fingers (fluid flow)• Rain clouds• Electrical discharges• Shorelines
Fractals in music: Music is pink noise
Am
plit
ude
Frequency
White noiseAf
Pink noiseAf-1
Brown noiseAf-2
Mathematics is relevant
It is everywhere, and part of everything, both inanimate and animate.
Science and Beauty“It is more important to have beauty in one’s
equations than to have them fit experiments.”
Paul Dirac
Can mathematics be beautiful?
Can science be beautiful?
Beauty“There is no excellent beauty that hath
not some strangeness in its proportion.” Bacon
“Beauty is the proper conformity of the parts to one another and to the whole.”
Heisenberg
Is science beautiful?
• Aesthetics play a major role in science
• Theories are advanced on the basis of their beauty
• Symmetry• Simplicity
Beautiful theories
• Strangeness: unexpected patterns, unexpected connections
• Conformity: unity, symmetry
Ugly theory• Ptolemy’s model: clunky, complex,
cumbersome• Circles upon circles upon circles• Variable speeds• Off center• Forced explanation of motions: new
motion-> new addition to theory
Beautiful theory: Newton’s gravity
Two simple equations:F=ma motionF=GMm/r2 gravity
Leads to beautiful elliptical orbitsExplains all celestial motionsUnifies gravity on earth and sky
Beautiful theory: Einstein’s General Relativity
T8G Matter tells spacetime how to curve, and curved space tells matter how to move.
General Relativity
• Unifies properties of space and time with properties of matter and motion.
• Previously thought to be entirely separate.
• Shows delightful, and utterly unexpected, connections with thermodynamics and electromagnetism
More unexpected patterns
Black hole Black hole
Incoming electromagnet
ic wave
Incoming gravity
wave
Reflected electromagneti
c wave
Reflected gravity wave
Reflected waves
have exactly
same energy
Science and beauty• Why does aesthetics play such an
important role in science?• Perhaps our notions of “beauty” reflect
a concordance with the underlying mathematical structure of Nature.
“Beauty is truthtruth beauty-that is all
Ye know on earth and all ye need to know” (Keats)
The Big Ideas
1. EmpiricismObjective observation
(experimentation) decides what is true
The Big Ideas
2. Universal LawsTerrestrial laws and celestial laws are
identicalThe same simple forces are at work in
the sun and on other planets
The Big Ideas
3. GravityEvery bit of matter in the Universe
attracts every other bit of matterA very simple law explains all the
motions observed in the solar system.The predictions from this simple law
are astonishingly accurate
The Big Ideas
4. Wave-Particle DualityThe microscopic world is different.Matter sometimes acts like particles, sometimes like waves.Light sometimes acts like particles, sometimes like waves.At its root, reality exists as waves of chance.
The Big Ideas
5. The Big BangThe Universe began from a very hot,
very dense state about 14 billion years ago.
The Universe continues to expand and evolve.
The Big Ideas6. We are stardust
All the elements heavier than hydrogen formed inside of stars.
These stars exploded and sprayed these elements out into space.
The elements in our bodies (such as carbon and oxygen) ultimately originated in the centers of stars.
The Big Ideas
7. The origin of the solar systemStars and planets are continuously
forming.The sun and its planets formed about
4.5 billion years ago from an interstellar cloud of gas and dust.
The earth and the other planets formed at the same time in a gaseous disk surrounding the young sun.
The Big Ideas
8. Plate tectonicsThe surface of the earth consist of
moving plates.Motions of these plates are responsible
for forming new ocean crust, mountain ranges, earthquakes, and volcanoes.
The Big Ideas
9. The earth is ordinaryMankind inhabits an ordinary planet,
orbiting an ordinary star, in the backwaters of an ordinary Galaxy
Our place in the Universe is NOT special
Life may well exist elsewhere