The History of Classical Gravitational Theory and General Relativity

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The History of Classical Gravitational Theory and General Relativity

In the beginning scientists and religious men of their era tried to explain the universe both biblically and scientifically. One of the foremost Greek scientists was Aristotle; taught by Plato, that the circle and sphere are the two most perfect shapes in a 2 and 3 dimensional universe, Aristotelian system placed Earth at the center of the universe; and all other heavenly bodies revolved around the earth in crystalline orbitals. Another Greek Mathematician, Aristarchus theorized that the sun was the center of the universe and that the Earth revolved around it. His simple reasoning was constituted purely by the fact that the Earth is a much smaller body than the sun, and the smaller should orbit the greater. By the 2nd century CE it became more and more apparent that the simplistic models derived nearly 2000 years before, were flawed. Kepler, a Scientist of the early 1600s concluded not only that the previously stated purely circular orbitals around the sun were in fact ellipses, and that planets travel faster when near the sun, and slower when farther from the sun, and lastly he found that the mathematical relationship between the orbital period, and the orbital radius of any given planet. While Kepler was creating a new model of the universe Galileo Galilei was tearing apart the out dated Aristotelian system. Conceiving the theory of inertia, disproving the concept that all planets orbited the Earth (essentially providing the proof Aristarchus’s theory lacked) disproving the Catholic church’s geocentric model that had become so fundamental to its dogma, and lastly left a major concept of physics unexplained, to an influential scientist, that was born the year Galileo died.

Isaac Newton the man that finally unified Earth and the heavens discovered the weakest force in our universe; gravity. Having inherited all the works of physicists previous to his time, Newton deduced that there was a force that pulled matter towards it. He concluded that the same force that pulls an apple to the Earth also holds the planets and moons in orbit. Prior to Newton no one had considered that the Earths gravity extended into the heavens above, much less that solar gravity bound the planets to their orbits around the sun. By using Kepler’s laws, geometry, algebra, and his new laws of motion he was able to pull everything together to explain the universe in a very basic way; the law of universal gravitation. This law states that the attraction between any two bodies in the universe is directly proportional to the product of their masses, as well as inversely proportional to the distance between them squared. Or… FG = GMm/R2

“Newton's work in mechanics was accepted at once in Britain, and universally after half a century. Since then it has been ranked among humanity's greatest achievements in abstract thought. It was extended and perfected by others, notably Pierre Simon de Laplace, without changing its basis and it survived into the late 19th century before it began to show signs of failing.” (http://www.newton.ac.uk/newtlife.html)

As well as the Law Of Universal Gravitation, Newton also began to calculate and explain the aspects of motion that had so eluded physicsits before. Newtons first law of motion states that an object in motion stays in motion unless acted on by an outside force and therfore an object at rest will stay at rest unless acted on by outside force. This law allows for equilibrium of soliditary objects and in objects in motion that are not in acceleration.

Our universe as we know consits of 4 fundamental forces:

1. electromagnetic force

2. nuclear forces

3. “ ”

4. gravity-holding it all together.

The problem is, all the other forces seem to be ballanced; equaling each othre out. Gravity on the other hand doesn’t want to cooperate. Gravity...
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