Physics of the Impossible

Michio Kaku's organizing claim is that the word impossible is doing too much work in ordinary language. Many technologies dismissed as pure fantasy, invisibility cloaks, phasers, teleportation, faster-than-light travel, are not forbidden by any known law of physics; they're simply beyond current engineering capability, sometimes by a wide margin. Kaku sorts these ideas into three classes based on how far they sit from today's technology and how confidently physics can say they might eventually work, ranging from things achievable within a century to things that would require rewriting fundamental theory.

This matters because it reframes science fiction as a genuine, if speculative, extension of physics rather than mere fantasy, and because it teaches readers to distinguish between things that are merely hard and things that actually violate conservation laws or the speed of light. Kaku uses each supposedly impossible technology as an occasion to explain the real physics, from electromagnetism to quantum mechanics to general relativity, underlying why it's difficult and what a genuine breakthrough would require.

Who should read it

Curious general readers who grew up on science fiction and want a physicist's honest accounting of what's plausible, along with students looking for an approachable, example-driven tour of core physics concepts. It works well for anyone who wants big ideas in cosmology and quantum theory explained through familiar cultural references rather than equations.

About the author

Michio Kaku is an American theoretical physicist and professor at the City College of New York, known for popularizing physics, including string theory, through numerous books and media appearances.