The book in your hands develops the best traditions of the Russian scientific popular literature. Written by working theoretical physicists, who are, at the same time, dedicated popularizers of scientific knowledge, it brings to the reader the latest achievements in quantum solid-state physics, but along the way it also shows how the laws of physics reveal themselves even in seemingly trivial episodes concerning the natural phenomena around us. And most importantly, it shows that we live in the world, where scientists are capable of "proving harmony with algebra".