The book "Worlds within worlds: The history of nuclear energy, Volume 1 (of 3). Atomic masses; Energy; Electricity" by the famous writer Isaac Asimov is a fascinating exposition of the history of the development of nuclear energy. The author examines in detail the atomic weights of elements, various aspects of energy use, and the role of electricity in the modern world. Through his classic narrative skills, Isaac Asimov explains complex scientific concepts in an accessible manner, making the material comprehensible to a wide range of readers. The book "Worlds within worlds" is not only a lecture on physics, but also a journey into the world of science, which constantly changes our vision of engineering, technology and energy. This first part of the trilogy invites readers into the exciting world of nuclear energy, where they can learn a lot of new and exciting things about the principles of the functioning of atoms and the energy systems of the planet.