Copernicus, Kepler and Galileo

(Originally written February 2, 2006 in Book 4)

A History of Western Philosophy, Vol. 3
W.T. Jones

Copernicus

-It was the rebellion against Aristotle and Aristotelians that created a climate for Copernicus to produce a heliocentric theory. Thus began the Neoplatonic and Pythagorean revival. It made it 'Ok' to suggest the universe ran in accordance with simple mathematical principles rather than with a constant divine manipulation.

- The grafting of Pythagoreanism into Christianity created an idea of an omnipotent creator who was in fact an omniscient mathematician. This inspired the mathematical study of nature.

-Copernicus assumed two things about the earth:
1) It revolves on its axis
2) It turns in a circular path around the sun between Mars and Venus

-Copernicus was hesitant to publish his thoughts because of fear of the Church's reaction. However the Church took little notice of the heliocentric theory until Galileo popularized the theory 60 years later.

Kepler

-While not a great observer, Kepler did have a keen sense of generalizing and synthesizing. He could discover simple uniformities hidden beneath the rich diversity of concrete facts.
-Kepler was devout Lutheran but he was convinced of a God that created the universe to work on simple mathematical harmonies and principles.
-Kepler had three laws:
1) The planets orbit in ellipses around the sun
2) Each planet moves at varying speeds around the sun. As a planet travels from A to B the area ABS is swept out. As it travels from C to D the area CDS is swept out. If the time it takes to travel from A to B is equal to that of C to D, the areas of ABS and CDS are equal.
3) The square of the periodic times are proportional to the cubes of the mean distances from the sun.
-Kepler's laws were a great achievement in astronomy but what they depend on is a great achievement in knowledge. They are based on two things:
1) The framing of hypotheses
2) The mathematization of data for the purpose of confirming or disconfirming the framed hypotheses.

Galileo

-Galileo discovered four moons orbiting Jupiter
-Galileo's contemporaries (aside from Kepler) knew that Galileo could have only produced the moons of Jupiter by witchcraft or by slight of hand because it would have other wise rendered their theory that God created seven heavenly bodies incorrect
-Galileo wrote "Dialogues concerning two new sciences", which is one of the most important contributions to the development of science.
-Dialogues analyzed the ranges of the behavior of bodies on earth including:
1) Resistance to fracture
2) Causes of cohesion
3) Uniform motion
4) Naturally accelerated motion
5) Violent motions