Modern physics without the theory of relativity is almost as impossible as without the idea of ​ ​ atoms and molecules. This theory is one of the "difficult" to understand a fairly wide range of readers. That is why it is especially valuable that the reader receives the main provisions and ideas of the theory of relativity "first-hand" - the authors of this book are academician, laureate of the Lenin and Nobel Prizes, L.D. Landau and Professor Yu. B. Rumer.