Physics of the Impossible: A Scientific Exploration into the World of Phasers, Force Fields, Teleportation, and Time Travel

The boundary between the impossible and possible is a central focus of Physics of the Impossible, as the title suggests. Much of the book discusses the application of real-world science to fictional technologies, and how developments in the science, technology, math, and engineering (STEM) fields could one day produce technologies capable of emulating feats once considered impossible. Kaku consistently blurs the line between what can and can’t be done by showing how scientific progress continually expands the boundaries of possibility.

Beginning in the Preface, Kaku introduces gradations of impossibility through his classification system for speculative technology. Class 1 technologies did not exist in 2008, but Kaku believed that they would become available within decades. Class 2 technologies may be possible for societies thousands or millions of years more advanced than 21st-century human civilizations, but are not likely to become feasible in the foreseeable future. Class 3 technologies defy our knowledge of the laws of physics and cannot be possible unless our understanding of the universe undergoes a fundamental shift. Notably, the technologies categorized as Class 1 impossibilities far outnumber those of the other two categories, indicating that many futuristic feats are well within the bounds of possibility and likely to become reality in the near future.