The book "Worlds Within Worlds: A History of Nuclear Energy, Volume 3 (of 3): Nuclear Fission; Nuclear Fusion; Beyond Fusion" by the famous writer Isaac Asimov is a fascinating journey into the world of nuclear energy. In this book, the author examines the processes of nuclear fission and nuclear fusion in detail, revealing their essence and principles of action. Through the prism of facts and his own research, Asimov talks about the achievements of mankind in these fields, as well as the importance of the development of nuclear energy for the future of our planet. The book also considers the prospects of using more productive technologies that will change the perception of energy. This interesting study will be useful not only to specialists in the field of nuclear physics, but also to a wide range of readers interested in the science and technology of the future.