Question

Can anyone explain me theory of relativity? ​

Answer 1

There are 2 theories of relativity: General Theory and special theory.

In special theory of relativity, everything is based on the fact that speed of light is constant and all inertial frames are equal. Due to this a moving observer observe complete different things then a stationary observer.

General Theory: the special theory is valid in inertial frames. For non inertial we use general relativity. It describes gravity as a pseudo force and attributes it as geometry in space time. It does because there is nothing like action at distance as special relativity limits the speed of information.