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Einsteins Theory Of Relativity Essay, Research Paper

When astronomers gaze out to the heavens these days, they see planets, stars and other celestial bodies. They understand how they move in relation to one another and the space they are in. This is due to the works of Albert Einstein nearly a century ago. Before then they were limited to understanding the universe based on the predictions, observations and calculations of mainly Isaac Newton. They were the backbone of classical physics, defining the world using the simplest of calculations. Newton s calculations were made using the primitive devices available in the seventeenth century. As technology advanced through the ages, problems became apparent with the simple calculations, and formulae of Newton. They allowed for holes in the way they described nature. These holes did not allow for the true nature of light, time and space. Nor did they explain certain phenomena encountered in the Michelson-Morley experiment. This led to the development of Einstein s theories of Special, then General Relativity, which redefined the world, and abolished many required aspects of classical physics.

Classical physics was based on assumptions that the world can be defined with absolute constants. One such assumption was of the ether. The ether, proposed by Newton, was a connecting medium for light to travel and for forces of attraction between bodies in space to be conducted (Guggenheimer 33). Newton suggested this to make up for the phenomenon that his formulae would not allow for. From the beginning there were inherent flaws with ether theory. One problem is that its criteria do not fit together. Ether theory contradicts its self, it must be absolutely rigid, absolutely elastic, and it must also must be absolutely soft because all matter moves through it with out losing velocity (Yilmaz 9).

Another assumption was that Absolute or Universal Time exists. Stephen Hawking, who has the same post at Cambridge University once held by Newton, states that, Absolute or Universal time [is the time] that all clocks would measure (70). This means that all clocks measure time the same regardless of their frame of reference.

Newtonian physics are based on the assumptions that the quantity t = t for all relative frames of reference (Yilmaz 6). The value for time, t, with respect to the motion of a body measured from one point of reference, and t is time measured from another point of reference. This assumption means that for inertial or uniform frames of reference time is constant or absolute.

The most accurate experiment ever conducted to determine the properties of the ether and tie together the loose ends of Newton s laws of physics was the Michelson-Morley experiment. American physicist Albert Michelson and American chemist Edward Williams Morley, tried to determine the velocity of earth relative to the ether (Bornstein and Gamow 1). The other aspect and finding of the experiment as Hawking recalls is:

They compared the speed of light in two beams at right angles to each other. As the earth rotates on its axis and orbits the sun, they reasoned, it will move through the ether, and the speed of light in these two beams should diverge. But Michelson and Morley found no daily or yearly differences between the two beams of light. (67)

According to classical physics if the earth were moving towards a ray of light from the sun then the speed of light should be less in relation to the speed of earth; such was the prediction of the Michelson-Morley experiment (Guggenheimer 88). They hoped that the ether would speed up the earth s velocity relative to the sun at one point of the year, and six months later the velocity would be slower but in the opposite direction; thus lead to the conclusion that the ether at certain times of the year should alter the speed of light. The result of the experiment however was that the velocity of the earth was zero (Bornstein and Gammow 1-2). Also the speed of light remained constant as observed from earth (Yilmaz 14). This experiment s failure led to more questions.

Albert Einstein would answer the questions of the ether, the speed of light, and constancy of time or lack there of. In 1905 Albert Einstein published his paper on Special Relativity, which cuts through the ether and solved the speed of light problem once and for all (Hawking 67). Einstein breaks away from ether theory because light rays would not be tied to a medium and not transmitted by one (Yilmaz 6). In order for Einstein to develop his theory, he had to drop many of the absolutes of Newtonian physics, specifically the notion that there is absolute or universal time (Hawking 70). Einstein determined from the Michelson-Morley experiment that, the velocity of light is c in all directions for observers moving uniformly with respect to each other (Yilmaz 14). Einstein, also says that unlike sound waves which are dependent of a medium for transmittance, light is the only mode of motion that shows itself to be entirely independent of the carrier of the motion, of the transmitting medium (Moszkowski 195). Guggenheimer explains Einstein s theory of how time itself can be relative;

To illustrate, let us imagine a clock placed on the sun, of identical construction with one placed on the earth, the sun being assumed to be stationary relative to the moving earth; and let us add the further assumption that the respective masses and other conditions of the earth and sun are equal a beam of light, measured by the clock on the stationary sun, travels at the velocity 186,000 miles per second. According to the orthodox principle of relativity, to an observer on the earth the beam travels at the apparent speed of 93,000 miles per second. According to the law of constancy of the velocity of light to the observer on earth the velocity of light is still apparently 186,000 miles per second. (98-99)

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