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


Edward Weston


Edward

Weston

Rotational Symmetry

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

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

basic natural science

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