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Aristotle: Gravity Theory
Had the idea the the four elements of the earth (fire, water, earth, air) had their proper places and the heavier elements return towards the center of the universe; heavier objects fell faster as it contained the heavier objects -
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Ptolemy: Gravity Theory
Geocentric Theory; the earth was the center of the universe, it stays at rest so everything revolves around it. He made a system of circles and epicycles that show the motion of the planets and stars revolving around the earth and everytime an observation didn't agree to the theory, he added another epicycle so the motion stays perfected -
Newton: Gravity Theory
When hit on the head with an apple from a tree he was sitting under, he thought of its acceleration as a cause of gravity. Newton's orbital cannon proved that if cannon was fired horizontally from mountain, it would either fall or orbit, depending on velocity, and he also made a point that the moon has neither acceleration or gravity, since it hasn't fallen onto the earth. He also theorized that any two objects that have mass have a gravitational attraction between each other. -
Cavendish: Gravity Theory
Measures the value of G (gravity), leading to the first accurate value for the gravitational constant; used to measure the mass of the sun and the weight of earth -
Einstein: Gravity Theory
gravity was part of relativity; gravity was not a force, but a curve in space-time; based on an idea that because of gravity, objects moving in straight parallel lines will intersect because there paths become spherical; states law of mass-energy conservation: e=mc2