HPS211H1 Lecture Notes - Lecture 2: Sailing Ship, Deferent And Epicycle, Antoine Lavoisier
2 Mar 2016
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Geocentric ie. the earth doesn"t move because that would be 1) unnatural 2) noticed by us. The earth"s a sphere in the center of the universe. All natural motion is directed towards or away from the center of the earth. Motion that is not towards/away from center of earth is forced/unnatural. Heavy objects (earth) fall faster than lighter objects (us). Weaknesses- 1) deferents and epicycles complicated the supposedly simple universe. 2)tycho brahe"s observation of a new star with no stellar parallax meant the heavens are corruptible. The sun is at the center and earth revolves around it. Strengths- 1) explanation for retrograde motion of planets. 2) able to calculate distance of planets from. 3) able to calculate period of planets around sun. G"s changes to notion of matter and motion- 1) movement or rest at constant speed is the natural motion for earthly bodies. 2) objects fall at a rate independent of their weight.
