Albert Einstein developed the two parts of the theory of relativity between 1905 and 1915.
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Courtesy of Tracey Keifer. Emilio Segre Visual Archives. American Institute of Physics.

The Theory of Relativity

Albert Einstein was a very famous scientist. He thought up one of the most famous scientific theories ever. That is the theory of relativity.

Einstein thought up the theory of relativity between the years of 1905 to 1915. The theory of relativity has very new, different, and strange things to say about the Universe.

Light moves incredibly fast. It goes so fast, it could circle the Earth eight times in one second! If objects move really, really fast... almost as fast as light... strange things happen. The moving object gets shorter. Time slows down for it, and clocks on it run more slowly. Two people might not agree whether some events happened at the same time or not. These are some of the wacky things that relativity theory tells us!

Have you ever heard of Einstein's famous equation, E = mc2 ? That equation is also part of the theory of relativity. The equation says that it is possible to turn matter (the "m" in the equation) into energy (the "E" in the equation).

The theory of relativity also says that the "shape" of space can be "curved". Space can be curved near large objects that have a lot of gravity. Even rays of light curve when they pass near a very massive object. That is why black holes can "suck up" light that passes close to them.

Last modified June 16, 2008 by Randy Russell.

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