AaronV


 * While the Theory of relativity can be difficult to understand, it is not impossible. There are three ideas that can be learned that can help understand the theory of relativity. First, time can appear to be affected by speed and gravity, as seen in the idea of time dilation and the principle of equivalence. The second idea is the principle of equivalence itself. The final idea is the actual theory of special relativity.

Galileo originally developed a theory of relativity. In his idea, Galileo stated that the only velocities that are important are relative velocities. (Wright) Later, Albert Michelson and Edward Morley conducted experiments to see if the speed of light was affected in any way by different substances. These experiments demonstrated that the speed of light remains constant at 186,282 miles per second. (Dine)**

Speed and gravity can appear to affect gravity. The Principle of Equivalence explains acceleration in zero gravity can produce the same effects as gravity itself and also helps to explain some of the effects of gravity on time. According to the theory, "If an elevator far out in space accelerates upward at 10 meters/second2, it will feel like a downward acceleration of gravity at 1 g = 10 m/s2." (Wright) According to this principle, as the example given by Professor Wright, if a clock on the elevator flashes a light, say once a second, then a person standing on Earth who could see that flash of light would see that light flash more than once per second. This results from the elevator's acceleration resulting in a phenomenon known as the Doppler shift. (Wright) Time dilation thus occurs.

The Principle of Equivalence, as developed by Albert Einstein and confirmed by Lorand Eotvos in 1889, states that the inertial and gravitational mass of an object are the same. The inertial mass is how much inertia an object possesses, while gravitational mass is how much gravity is acting on that object. Einstein was able to use this principle to show how gravity affected space-time's structure. A theory of this principle given by Einstein was that light was able to be bent by the gravity ofthe sun. (Dine)

The theory of special relativity states that "the velocity of light is special." (Wright) If an object is traveling at the speed of light, it will always travel at the speed of light, no matter what the reference frame. This is not true for other velocities, which would be affected. (Wright) Also stated by the theory is that no matter what the inertial fram, the laws of nature remain constant. (Dine)

As shown, speed and gravity can affect the rate of time. This is seen in the Principle of Equivalence, showing that intertial and gravitational masses of objects are the same. Finally, while all velocities except that of light are different depending on your reference frame, the laws of nature remain the same. Time Cone from Time Dilation

__Works Cited__ Dine, Michael. "NASA - Relativity." __NASA - Home__. 29 Nov. 1007. 5 Feb. 2009 http://www.nasa.gov/worldbook/relativity_worldbook.html. Dine provides information on this website about some of the original theories of relativity developed by Newton and Galileo. Dine thendiscusses other areas related to relativity, such as time dilation and Lorentz Transformations. Wright, Edward. "Relativity Tutorial." __www.astro.ucla.gov__. 2 Feb. 2008. 4 Feb. 2009 http://www.astro.ucla.edu/~wright/relatvty.htm. Wright starts in this essay by providing a brief history about the development of the theories surrounding relative. This website provides a good amount of the math and equations involved in relativity. It also provides information regarding various related pieces of information such as time dilation and the principle of equivalence and related math. This website appears to be credible for a few reasons. First, the author, Edward L. Wright, is a professor at UCLA. Second, Wright provides a large bibliography of sources he got information from.