I began preparations to publish this book in English at the end of 1991; for a number of reasons, this stage stretched to several years. An oriental adage says: ‘Hours tick away, days run away but years fly away.’ These words are a reflection of our subjective perception of time intervals in the past, of what we remember of them. For most people, the feeling of the flight of time is considerably intensified when one turns in one's mind's eye to larger and larger blocks of time which one has lived through. I distinctly feel now that it was virtually yesterday that I was writing this book, even though several years separate me from those days and so much has happened and so much has changed. In that period, I began working in a new place, as astrophysics professor of Copenhagen University. My native country, the former USSR, the former enormous empire, broke into pieces and is trying, in untold hardship for its peoples, to claw its way out of the frightening historical abyss into which it had been plunged. Even though I continue to head the Department of Theoretical Astrophysics of the Petr Lebedev Physics Institute in Moscow, my settled life beyond the borders of my native land, in a very different world, has definitely changed my perception of life, although to a considerably lesser degree than I could have predicted. It involves my attitude to this book as well.