hie !!! i want to know about einsteins special theory of relativity?

Answer 1

I'll start with you the same way Einstein started with his own Special Relativity. Imagine that there are 2 parallel train tracks, and 2 long trains going opposite directions on the tracks. Imagine that there's a long ruler marked along the length of each train, and that at every window there's a clock. Imagine that there are many observers on both trains, taking notes of what they see in the other train as well as their own.

You would EXPECT that when observers of one train measure the length of the other train, it would seem to be of normal length, no different than it is at rest. You would EXPECT that all the clocks on both trains would show exactly the same time.

Special Relativity shows that in fact the length of the other train looks shorter when it's moving, and that the clocks of the other train are not only running slower, but are not even sychronized, i.e., the clocks in the back of the train don't match the clocks in the front. More strangely, and harder to understand, observers of BOTH trains would see the same thing about the other train that's moving relative to them.

Because of these strange things that don't make sense, many people run into "paradoxes" when thinking about these things, and then say Special Relativity can't be true. It is true, it's mathematically established, self-consistent, and a hundred years of experimentation has demonstrated it. Almost all of the "paradoxes" stem from a less-then-clear understanding of exactly how it works. Here's an introductory wiki on this:

Answer 2

I suggest you get one of the many books that have been published on it.