Ancient Greeks

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Ancient Greeks
Tried to explain nature with models Geocentric
model heavens must be geometrically perfect
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Earth Flat or Round?
Round - Pythagoras 500 BC Evidence
Aristotle Earths curved shadow on the moon
during lunar eclipses.
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Size of the Earth
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The Greek Explanation for Retrograde Motion
Click Here
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Islamic Science

• Translated Greek work and continued to study the
  sky the name of science AND religion. Much of
  the success was due to their openness.
• Developed instruments and techniques for studying
  the sky.
• Found problems with timekeeping methods used by
  the Greeks ? developed much more advanced math
  (algebra, trig.) in the process of fixing this.

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The Dark Ages

• Not much happened in science here
• Dominated by religion, ignorance and oppression.

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Nicholas Copernicus (1473-1543)

• Earth might not be the center of the universe
  (not a new idea)
• His model, where the outer planets moved slower,
  explained the problem of retrograde motion.
• (Orbits of the planets were circular)
• Still problems with the theory he couldnt
  predict the positions of planets any better than
  Ptolemy

Click Here
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Tycho Brahe (1546-1601)

• Built an accurate naked-eye observatory
• Collected a wealth of data positions of sun,
  moon and planets almost daily for 20 years.
• Not able to measure parallax (so he claimed
  Earth was stationary)
• Lost part of his nose in a duel (wore silver and
  gold replacements)
• Tychos Nova
• Measured positions (4) of 777 stars
• (he had his own jester!)

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Johannes Kepler (1571-1630)
New idea!!! ? elliptical orbits This reconciled
the data that Tycho collected with a solar system
model.
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Keplers First Law
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Keplers Second Law
Click Here , and Here
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Keplers Third Law
More distant planets orbit the Sun at slower
average speeds, obeying p2 a3, where p is the
period in years and a is the average distance
from the sun in AU.
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Keplers Laws
1. The orbit of each planet about the Sun is an
ellipse with the Sun at one focus. 2. As a
planet moves around its orbit, it sweeps out
equal areas in equal times. 3. More distant
planets orbit the Sun at slower average speeds,
obeying p2 a3, where p is the period in years
and a is the average distance from the sun in AU.
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Galileo Galilei (1564-1642)

• First to put a telescope to real work (not
  inventor)
• Moons orbiting Jupiter ? NOT ORBITING EARTH
• This was concrete evidence that the Earth isnt
  the center of the universe!
• This same thing can be reproduced with a pair of
  binoculars

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Galileo Galilei (1564-1642)

• First to put a telescope to real work (not
  inventor)
• Observed mountains and valleys on the moon.
• Milky Way could be resolved into stars.
• Phases of Venus similar to the Moon.
• Sunspots.
• Harassed by the church Copernican books banned

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Role of the Church
The textbook has a very bias view of this
notice their note on agreement between the church
and science apparently they arent aware of
Evolution Theory vs. intelligent (ignorant)
design. Why is intelligent design not a
scientific theory?
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Scientific Method
Hypothesis vs Theory
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Principles of Science
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Occams Razor
one should not increase, beyond what is
necessary, the number of entities required to
explain anything
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Copernicus vs. Ptolemy
Neither were very accurate Which one is
simpler? Circular orbits around the sun
or Are elliptical orbits simpler than compound
circles?
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Objectivity
Everyone (it seems) is biased one way or
other ?Canals on Mars. ?Experiments in
radioactivity
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New Ideas
Difficult to new ideas accepted due to ingrained
beliefs
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Need for an Open Scientific Community
This keeps everyone in check Similar to the
way our government is supposed to work
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Scientific Method Review
Observe, predict and test. Modify, simplify,
predict, test. Find more ways to test
hypothesis/theory.
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Astrology
Seeking correlations between events on Earth and
relative positions of the Sun, Moon, and
planets. Not science continued today in
horoscopes, with the phrase for entertainment
purposes only tagged on in fine print for legal
purposes