What is Einstein's general relativity, in a nutshell? This is a theory that has its advantages and disadvantages, or a straight ruler with which we can measure distances in our universe, but there is one small problem that there are no real straight lines in space, everything moves in circular, spiral orbits and we have to make corrections all the time. In this sense, the theory is very crude and cannot be applied in real life, but it contains very good logic that you cannot go against. Namely, that everything in this world is relative and the result does not change by rearranging the places of the terms. So you sit at the station in a carriage and look at the freight train standing next to you, and now it has started moving, it seems that you have gone, but your neighbor continues to rest. Looking out the other window, seeing the motionless platform, you immediately realize that you are still standing. This book is conditionally the same second window in which everything is normal and there are no distortions. Published in the author's edition, preserving the author's spelling and punctuation.