It came to be accepted when everybody who had the equipment and the ability
began to measure it and found that it's true. It's been observed thousands of
times in the past hundred years or so. And at places like the Livermore National
Laboratory, the Stanford Linear Accelerator, the Argonne National Laboratory,
the CERN, and the LHC, it's observed every day.
einstein came up with the general theory of relativity
While Einstein was a great scientist, who accomplished much, he is probably most famous for his theory of relativity. ( E=MC2 energy equals mass times light squared)
albert Einstein
Einstein's theories were General and Special Relativity. Hawking put forward a theory combining relativity with quantum mechanics.
Albert Einstein introduced the "Matter Energy Equivalent" a part of "[General]Theory of Relativity" on September 27th 1905; it was from this work that the famous E=MC2 is taken.
It took Albert Einstein about 10 years to develop his theory of general relativity, from around 1905 to 1915. The special theory of relativity, which dealt with the relationship between space and time, was developed earlier in 1905.
Currently, the most accepted theory is that it resulted from a crash between a large planetoid (or "protoplanet") and Earth.
Sir Isaac Newton's theory of gravity was written in 1687, however he did not come up with a theory of relativity. The first person to come up with a theory of relativity was Galileo Galilei, but this theory turned out to be incorrect. In a paper in 1905 Albert Einstein built upon Galileo's ideas and produced the special theory of relativity. This is a very famous paper that turned the physics world on its head. The equivalance of mass and energy in his most famous equation, was deduced as a result of this theory. Furthermore, In 1916 Albert Einstein produced the General theory of relativity, a theory of gravitiation which is an extremely successfulvand famous theory. This is the gravitation theory that we use today, as it is supremely accurate. However, Newtons theory of gravitiation works well for speeds much less than the speed of light in a vacuum, and has the benefit of being much less complex!
A scientific theory is an extensively tested hypothesis that is accepted as the best answer we can come up with, since nobody has been able to prove it wrong yet.
Because it has been proven by many experiments by many scientists
Albert Einstein developed the formula E=mc^2 in 1905 as part of his theory of special relativity.
He did not use any databases to come up with E=mc^2.