Albert Einstein developed the two parts of the theory of relativity between 1905 and 1915. Click on image for full size (219 Kb) Image courtesy of Tracey Keifer, Emilio Segre Visual Archives, American Institute of Physics.

Albert Einstein developed one of the most famous theories in the history of science, the theory of relativity. This theory actually has two parts: the special theory of relativity and the general theory of relativity. These two theories introduced some very new, different, and strange ideas about the basic nature of the Universe.

According to special relativity, very odd things happen when an object moves at nearly the speed of light. Time slows down, the length of an object becomes shorter, and the mass of the moving object increases. If two observers are moving relative to each other, they may disagree as to whether two events happen at the same time. Mass and energy can be converted back and forth according to Einstein's famous equation, E = mc². Einstein introduced the special theory of relativity in 1905.

The general theory of relativity claims that the "shape" of space itself can be curved near large objects that have a lot of gravity. In fact, according to relativity, gravity isn't so much a force as a curvature of space. Even rays of light curve when they pass through the space near a massive object. This is why black holes can "suck up" light that passes near them. Einstein developed the general theory of relativity between the years of 1907 through 1915.

Albert Einstein developed the two parts of the theory of relativity between 1905 and 1915. Click on image for full size (219 Kb) Image courtesy of Tracey Keifer, Emilio Segre Visual Archives, American Institute of Physics.

Albert Einstein was one of the most famous scientists of all time. Einstein thought up one of the most famous scientific theories ever. That is the theory of relativity.

The theory of relativity has two parts. The first part is the special theory of relativity. Einstein published the special theory of relativity in 1905. The second part is the general theory of relativity. Einstein came up with the general theory between the years of 1907 through 1915.

The two parts of the theory of relativity have very new, different, and strange things to say about the Universe.

The theory of special relativity says that strange things happen when objects move very, very fast. Light moves incredibly fast, around 300,000 kilometers per second (about 186,000 miles per second). If objects move almost as fast as light, strange things begin to happen. What kinds of strange things? Time slows down, the length of an object becomes shorter, and the mass of the moving object gets larger. If two people pass each other moving very fast, they may not agree that two events happened at the same time. 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 second part of the theory of relativity is the general theory of relativity. It says that the "shape" of space can be curved near large objects that have a lot of gravity. Even rays of light curve when they pass near a massive object. That is why black holes can "suck up" light that passes close to them.

Albert Einstein developed the two parts of the theory of relativity between 1905 and 1915. Click on image for full size (219 Kb) Image courtesy of Tracey Keifer, Emilio Segre Visual Archives, American Institute of Physics.

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.