Question

who wrote theory of relativeti.

Answer 1

it was written by Albert Einstein

Answer 2

The theory of relativity was known long before Einstein. Galileo Galilei, an Italian scientist of late 16th and early 17th century was the first to realise the necessity of testing scientific ideas with experiments and the first to emphasize the importance of Relativity in physical laws . This is the principle of relativity:
The laws of nature appear the same to all observers moving with constant velocities. Absolute velocity has no physical meaning. Only relative velocities are meaningful.
But all this was compiled by Albert Einstein.