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About Science

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Title: About Science


1
About Science
  • Physics 1010
  • Dr. Don Franceschetti
  • January 21, 2005

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.
  • The alignment of the planets determines the best
    time for making decisions.
  • Intelligent life exists elsewhere 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
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.

11
Important Dead Greek Guys
  • Thales of Miletus
  • c 624-c 547 B. C.
  • All things are full of gods

12
Important Dead Greek Guys
  • Heraclitus
  • All is change
  • Parmenides
  • Change is impossible
  • Zenos Paradox Achilles never catches up with
    the turtle.

13
Pythagoras 569-475 B.C.
  • Related musical harmony to numbers
  • Music of the spheres

14
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

15
Important Dead Greek Guy
  • Democritus
  • c. 460 c. 370 B. C.
  • Atoms unchanging, aggregates change.

16
Empedocles (fl c. 450 B. C. )
Influence on Hippocrates, too. Four humors
theory is related.
17
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

18
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

19
Copernicus (1453-1543)
  • De Revolutionibus Orbum Coelestum 1543 (note
    date)
  • Heliocentric Universe, but still orbits are
    circles

20
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.

21
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
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