The book review here is for Hyperspace, authored by Michio Kaku. As the name suggests, the book is focused on the concept of higher dimensions and their applications in physics. More specifically, the books covers a wide range of topics, from the history of hyperspace, extra dimensions in fiction, string theory, supergravity, and the quest for a theory of everything. If you're considering giving this one a read, the aim of this review is to give an overview of what this book is, and what it is not. A brief introduction While Hyperspace covers a wide range of topics in modern physics, from string theory to quantum mechanics, the central theme of the book is the concept of extra dimensions. While giving a history of the concept of these extra dimensions, Kaku demonstrates how geometry has become a guiding principle in much of modern physics. The book discusses how Einstein's general theory of relativity reduced the complex force of gravity to a theory of pure geometry, and how elegantly ALL of the 4 forces are unified under this geometric structure when extra dimensions are added. This central theme is still keep intact in later chapters about quantum mechanics and string theory. What this book is As mentioned above, this is a book about geometry and the applications hyperspace has for physics. While it explains how geometry has already given us a holstic vision of the universe through GR, it also goes into detail about how non-euclidean geometries may be able to help unify all forces of nature, and the resulting implications for cosmology. While this is about physics, it is more of a history book. That is to say, you will find a history of how our understanding of space and time have evolved, and what may await us in the future. What this book is not This is not a deep physics book. In fact, there is no math here at all, and this can only be considered an introduction to the theme of geometry in physics. While it does cover many fields of physics, the coverage is not very detailed and you certainly won't learn a lot about them from this book. Likewise, if you're looking for a detailed introduction to string theory, you'll want to grab a copy of Brain Greene's Elegant Universe instead. If you want an introduction to a much broader theme of great importance in modern physics, this will be worth your time. The book was written in 1995, before the second superstring revolution and M theory. Much material is absent. The Good This is the most entertaining book I have read in a long time. Kaku has a certain writing style that never becomes dry, and none the chapters dragged along. As a book covering the history of extra dimensions, I loved it. The concept of hyperspace in it's modern form takes place first in the 1800's, with mathematicians discovering non euclidean geometries. The early chapters explain how attempts to make physical use out of this new geometry were made, by physicists and spiritualists alike. For example, while scientists were attempting to see if the forces and matter could be explained with hyperspace, psychics and spiritualist frauds began claiming the spirit world to merely be a hidden dimension. From there, the breakthroughs of Einstein are explored, going on the look at modern uses of hyperspace, including supergravity and string theory. The bad I don't have many complaints about this book. However, there is much content in which Kaku inserts his own philosphical viewpoints. Not a major problem, but it would be nice if the author could avoid that. Is it worth reading? If you have any interest in the history of hyperspace in physics, art, literature and popular culture, you will enjoy this book. It's not a deep physics book, but is worth the read even if only for the history.