About Science

1
About Science

• Physics 1010
• Dr. Don Franceschetti,
• January 18, 2006

2
Science

• The body of knowledge that describes the order in
  nature and the causes of that order.
• The process of gathering knowledge about the
  world and organizing it into testable laws and
  theories.
• Much that is good in the world is not science.
• The term science is sometimes used to describe an
  organized body of thought in general
  (mathematics, theology, literary criticism). Not
  in this class!

3
Measurement

• The hallmark of good science. Important
  scientific measurements go back to Greece, third
  century BC. (those that we know about)
• Erastothenes measured size of the Earth about 235
  B. C. based on lengths of shadows
• Aristarchus estimated diameter of moon as 2/5
  that of earth from eclipse from width of Earth
  shadow on moon. (actually closer to 2/7)
  Distance to moon could then be found. (Coin
  blocking moon)

4
Sun

• Aristarchus also measured distance to Sun using
  right triangle. (ASA)
• Size of Sun from pinhole image.
• And so on.

5
Scientific method (Galileo, Bacon)

• Observe
• Hypothesis
• Predict consequences
• Test by experiment or observation
• Generalize
• This is a gross oversimplification!

6
Scientific Attitude

• Observation (preferably experiment) is the
  ultimate test.
• A scientific statement must be falsifiable
  (Popper).
• Human authority means little.
• Examples of unscientific statements
• The alignment of the planets determines the best
  time for making decisions.
• Intelligent life must elsewhere else in the
  universe.
• There will never be a safe storage mechanism for
  nuclear waste.

7
Science, Art and Religion

• Science seeks to discover order in the natural
  world. Like watching a game being played and
  trying to figure out what the rules are.
• Religion is concerned with purpose.
• Art is concerned with individual expression and
  creativity.
• There are some interactions (e. g. painting,
  musical instruments, origins)

8
Pseudoscience

• Belief systems which mimic science but are not
  falsifiable. Generally appeal to authority and
  resist criticism.
• Astrology
• Shamanism (pendulums, pyramids, crystals, etc.)
• Energy multiplying machines
• Alternative medicines?
• Psychoanalytic schools?

9
Physics is the Basic Science

• It explains
• Chemistry
• Astronomy
• Biology
• Geology

10
Physics will be presented

• As the child of philosophy and craft.
• In historical context.
• In relation to technology, wars, governments and
  how people live
• As a part of your inheritance.
• As a liberal art
• As the result of human effort
• Some pretty weird humans involved

11
Technology

• Is not science but the application of science to
  human wants and needs.
• The applications can be good or bad or hard to
  tell.
• Science per se is generally considered good,
  though there are ethical issues.

12
Important Dead Greek Guys

• Thales of Miletus
• c 624-c 547 B. C.
• All things are full of gods

13
Important Philosophical Dead Greek Guys

• Heraclitus
• All is change
• Parmenides
• Change is impossible
• Zenos Paradox Achilles never catches up with
  the turtle.

14
Pythagoras 569-475 B.C.

• Related musical harmony to numbers.
• Music of the spheres.

15
Astrology/Astronomy

• Worlds second oldest profession
• Celestial Sphere, planets (wanderers) hard to
  explain using circular motion
• Ptolemy (90-168 A.D.) Almagest allowed
  calculation of planetary positions for horoscopes

16
Another Important Greek Guy

• Democritus
• c. 460 c. 370 B. C.
• Atoms unchanging, aggregates change.

17
Empedocles (fl c. 450 B. C. )
Influence on Hippocrates, too. Four humors
theory is related.
18
Plato (c. 428-c. 348 B.C.)

• World was a pale reflection of ideal world
• Atoms were geometric shapes
• Triangles are elementary particles
• He thought circles were the perfect figures

19
Aristotle (384-322 B. C.)

• Kept 4 elements, added quintessence
• No atoms
• Terrestrial motions were natural or forced
• Heavier objects fall faster
• Celestial motions were circular
• Heavens were perfect with no change

20
Copernicus (1453-1543)

• De Revolutionibus Orbum Coelestum 1543 (note
  date)
• Heliocentric universe, but still orbits are
  circles

21
Galileo Galilei (1564-1642)

• Uses telescope to prove heavens are imperfect
• Principle of inertia, end of distinction between
  natural and violent motion
• All bodies fall with same acceleration when air
  resistance is negligible.

22
Sir Isaac Newton (1642-1727)

• Three laws of motion makes it possible to
  identify and quantify forces.
• Inertia
• Force determines change in velocities
• Action reaction law
• Law of Universal Gravitation
• Nothing special about the Earth