The theory of relativity
The relativity’s theory is a theory from which you can find out how the world looks for people who race around the world at an extremely high speed. Moreover, its motion must be uniform and straightforward – no increase or decrease in speed and no deviation from the straight path is allowed.
At the heart of the special theory of relativity is a very simple idea: it is impossible to know in any way whether you really are moving or not. But if you develop this idea, it turns out that the consequences of such seemingly innocent start are stunning. It turns out that the world is radically different from the way you still have it.
Assume that divorced two brothers-twins: one remained on Earth, and the other went to the sublight spacecraft in a long interstellar journey, and then turned back. So, the theory of relativity asserts that at a meeting, the astronaut will be younger than his remaining brother on Earth.
But even in those cases where the special theory of relativity does not affect our imagination, it always modifies, and sometimes makes a radical revolution of the old theories. Some of its implications are of great practical importance for electronics, for nuclear power engineering. In general, it is necessary for a real understanding of space and time in which we live.
From these discussions, in the end, a new theory of gravity arises, which is somewhat more precise in Newtonian terms under normal conditions, and probably far exceeds it in extreme conditions. It does not have much practical application yet and may never happen to have it.
Nevertheless, the study of the general theory of relativity – this is one of the most exciting lessons that fall into the throes of a curious person. It gives us a sense of genuine understanding of the properties of space and time.