EmilyS

The Theory of Relativity

Image: Bornstein **The History of the Theory of Relativity:**
 * The theory of relativity developed by Albert Einstein has two main parts. The Special theory of relativity, published in 1905 and the general theory of relativity, published in 1915. These theories explain the behavior of matter, energy, time, and space. Modern physics uses the theory of relativity as a foundation (Dine). **
 * The Special theory of relativity means that observers are restricted to use uniform relative motion, while the General theory of relativity considers observers in any state of uniform motion including relative acceleration. This is also a theory of gravitation (Harrison). **
 * Special relativity includes electricity and magnetism in simple extensions of Galileo and Newton’s relativity, Einstein’s conclusions include time dilation, length contraction and E=mc^2 (Wolfe). It has two parts: 1. There is no ether, therefore the speed of light is the same for all observers, whatever their relative motion and 2. The laws of nature are the same in all inertial frames. ** ** General relativity was created so to modify Newton’s law of gravitation so that it would agree with special relativity. This theory also explains the motion of the planets (Dine) **


 * Thesis: **
 * The Theory of Relativity has been confirmed in a number of ways since it was originally introduced. Einstein originally predicted that a ray of light would be curved in the immediate vicinity of a massive object, such as the sun. Modern scientists have proven this, using the locations of stars in relation to the sun during the eclipse. Secondly, the idea that space is curved and the universe is expanding is also related to Relativity. Scientists still disagree on the type of curvature of space; however, they have seen the expansion of the universe through the shifting of distant nebulae. Finally, the Theory of Relativity suggests time dragging which is how a massive rotating body will drag time and space around it as it moves. Modern scientists have used the movement of artificial satellites around the Earth to prove and confirm this theory. **
 * Proving how light Curves Near Massive Objects: **
 * Einstein origi   **nally predicted that a ray of light would b  **e curved in the imm   **ediate vicinity of a massive object, such as the sun. Modern scientists have proven this, using locations of stars in relation to the[[image:Sun.JPG align="right"]] sun during the eclipse. Einstein predicted an apparent shift in position of 1.754 seconds of arc for a star at the edge of the sun, shifting progressively smaller for more distant stars. To prove this expeditions first chose to a star that had the appearance of being very near to the sun. Because of the sun’s brightness, stars close to it are normally obscured by light. However, during a total eclipse stars near the sun can be accurately observed and their positions precisely measured. Two expeditions were sent out, one in 1919 and the other in 1922 to observe phenomenon completely verified Einstein’s predictions. More recently, tests were conducted using radio-wave deflections. The results agreed, within 1 percent, with Einstein’s principle of relativity (Bornstein).
 * Image: NASA the sun**

**Image from NASA**
 * Proving How Space is Curved and **
 * the Universe Is expanding: **
 * The idea that space is curved and the universe is expan[[image:black_hole.JPG width="248" height="187" align="right" caption="NASA: A Black Hole"]]ding is also related to Relativity. Scientists still disagree on the type of curvature of space; however, they have seen the expansion of the universe through the shifting of distant nebulae. British astronomers James Hopwood Jeans, Arthur Stanley Eddington, and Edward Arthur Milne spent much of their work devoted to extending the theory of relativity. This was made possible by extending the general theory of relativity to include electromagnetic phenomena, though no applications of this theory have o   **f as yet been generally accepted. Space was now thought of as curved, though while the curvature of heavy bodies are know, the curvature in empty space is not known. Scientists still continue to disagree even over whether it is a closed curve such as a sphere or an open curve such as a bowl (Bornstein). The most famous experiment with curved space deals with gravity’s ability to bend light as it passes through the warped space near a massive object, which has provided today’s scientists with very strong evidence of the existence of black holes (The Theory of Relativity). The theory of relativity has also led to the possibility that the universe is expanding, making it reasonable to believe that the history of the universe is finite (Bornstein).


 * Proving Time Drag: **
 * The Theory of Relativity suggests time dragging which is how a massive rotating body will drag time and space around it as it moves. Modern scientists have used the movement of artificial satellites around the Earth to prove and confirm this theory. The general theory of relativity states that a massive rotating body will drag space and time around with it as it movies. This effect, called fame dragging, increases as the mass and density of the object increases. In 1997, a group of Italian astronomers proved this by examining radiation that had been emitted when the gravitation pull of a dense neutron star sucked matter onto its surface (Bornstein). **

Nasa: Image of lights **   In Conclusion:    ** **
 * Einstein’s theory of relativity has been proven and expanded upon since its creation. Einstein originally predicted that a ray of light would be curved in the immediate vicinity of a massive object, such as the sun. Modern scientists have proven this, using the locations of stars in relation to the sun during the eclipse. The idea that space is curved and the universe is expanding has also been debated and while scientists still disagree on the type of curvature of space, they have seen the expansion of the universe through the shifting of distant nebulae. Finally, the Theory of Relativity suggests time dragging which is how a massive rotating body will drag time and space around it as it moves. These expansions and improvements on Einstein’s original theory have only helped society, and the insatiable thirst for knowledge that many scientists share is sure to only promote the further uses of the theory of relativity for future generations.

** Works Cited **
 * Bornstein, Lawrence. "Relativity - MSN Encarta." __MSN Encarta : Online Encyclopedia, Dictionary, Atlas, and Homework__. 27 Jan. 2009 . **

An encyclopedia entry written by Bornstein for MSN Encarta. Very reliable information that is easy to navigate. Information deals with experiments furthering Einstein's theory of relativity.
Dine, Michael. "Relativity." __NASA__. 27 Jan. 2009 .

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An explanation of the theory of relativity by a NASA writer. Though the language is very advance, the information is very much to the point and exact. As its written and supported by NASA, it is extremely credible and up-to-date information.===== Harrison, David. "Special Theory of Relativity." __UPSCALE Home Page__. 27 Jan. 2009 .

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An extremely detailed report on the theory of relativity. Though this is a rather difficult site to understand, but extremely informative. It is broken down into sections for easy navigation, which is extremely helpful to find any of the information needed. The source is very reliable as well as it is endorsed by the university of toronto.===== "The Theory of Relativity." __Curious About Astronomy? Ask an Astronomer__. 27 Jan. 2009 .

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A group of 25 graduate level Cornell Univisity students describing the Theory of Relativity and providing links to different sources for further research. Unbiased basic information, can send in any questions to the department to have them answered if further information is needed. Site is updated frequently and monitered by students at all times.====== Wolfe, Joe. "Relativity: Einstein's theory of relativity in animations and film clips. Einstein Light." __School of Physics at UNSW, Sydney, Australia__. 27 Jan. 2009 .

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This site is very helpful for basic information on relativity, but not much else. The animations are very helpful to understand the basic concepts. Questions for further reading are also presented, which is nice for research. The site is credible and reliable as well.=====