Question

What is relativity theory of Einstein

Answer 1

Einstein's theory of general relativity predicts that the space-time around Earth will not be only deformed but also twisted by the rotation of the planets. In his theory of special relativity, Einstein has determined that the laws of physics are the same for all non-accelerating observers. He proved that the speed of light in a vacuum is the same and does not matter the speed at which an observer moves. Thus, he found that space and time were interlinked into a single scale called as space-time scale and so the event that takes place at the same time for one observer might take place at different times for another observer.
The proof of E = mc2 requires knowledge of relativistic mechanics and four vector concept which is beyond the scope of your grade.
This will be taught in your graduation.