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

Physics of the Impossible: A Scientific Exploration into the World of Phasers, Force Fields, Teleportation, and Time Travel is a best-selling popular science book by physicist and futurist Michio Kaku. Published in 2008, this book discusses the feasibility of the speculative technologies found in science fiction, based on the known laws of physics and technological capabilities of the late 2000s. Written in an accessible style, the book blends rigorous explanation with imaginative exploration, demonstrating how ideas once confined to fantasy can serve as entry points for understanding physics. The book addresses several themes: The Expanding Limits of the Possible in Scientific Discovery, The Role of Storytelling in Advancing Scientific Inquiry, and The Impact of Collective and Individual Scientific Achievements.

This guide uses the 2008 USA Doubleday first edition.

Content Warning: The source material and guide feature depictions of ableism, death by suicide, and antigay bias.

Summary

The book consists of a Preface, an Epilogue, and 15 chapters divided into three parts. Each chapter focuses on a different speculative technology and its feasibility based on the technological capabilities and scientific knowledge at the time of the book’s writing. In the Preface, Kaku introduces himself and his credentials as a physicist. He outlines his plan for the main body of the book and cautions against dismissing speculative technologies and theories as absolutely impossible, providing examples from throughout history of when people (even renowned scientists) wrongly did so.

The book’s three parts represent three categorizations of impossible technology. The first part is by far the longest, containing 10 chapters. Kaku considers the technologies discussed in Part 1 “Class 1 impossibilities,” meaning that they will likely become possible within the next few decades or centuries. In each chapter, he describes the characteristics of the fictional technology and then explains the scientific theories and principles relevant to replicating the effects in real life. In addition, he discusses past and ongoing projects developing the technology and makes predictions about future developments.

Kaku first explores force fields, which are invisible barriers capable of levitating objects or deflecting projectiles. He discusses the development of plasma windows and layered barriers for defensive purposes and of magnetic levitation as a means of suspension and transport. Next, he focuses on invisibility, particularly the use of metamaterials to alter the refractive index of light. He then discusses phasers and Death Stars, otherwise known as beam weaponry, and the different methods by which humans might upgrade or weaponize laser technology for greater destructive power in the future. Kaku then turns to teleportation, the ability to travel long distances instantaneously. This discussion introduces quantum mechanics, which allows for teleportation on an atomic level, and an inquiry into the means of developing teleportation on a macro level. Next, he focuses on the ability to read and control the minds of others, known as telepathy. This discussion includes overviews of current brain scanning technologies and developments in the field of neural implants and the interpretation of brain waves.

Kaku then discusses psychokinesis, the ability to move objects and transform them with the power of one’s mind. Although this is impossible naturally, technological advancements in implants that transmit brainwaves to computers are in active development as disability aids, and nanotechnology could be the key to replicator technology. Next, Kaku considers the possibility of artificial intelligence (AI) in robots, something that was not yet a reality in 2008, although AI is now an everyday technology. Kaku then addresses the subject of extraterrestrials and UFOs, focusing on the likelihood that life exists on extrasolar planets and on efforts to contact extraterrestrial civilizations. Next, the author explores starships, particularly the different propulsion methods that could allow interstellar travel and the logistical issues inherent in long-distance space travel. Part 1 concludes by introducing the concept of antimatter and anti-universes. Antimatter can already be produced in tiny quantities and has potential as a future energy source. Kaku explains how anti-chemistry and anti-universes are real possibilities despite a lack of naturally occurring antimatter in the universe.

Part 2 is significantly shorter than Part 1, consisting of only three chapters. It addresses Class 2 impossibilities, or phenomena and technologies that do not defy the known laws of physics but are far beyond the scope or capabilities of current human civilization. They touch the boundaries of our current knowledge of the laws of the universe, but could nonetheless be possible for significantly more advanced civilizations. Kaku discusses this classification of impossibilities, first addressing faster-than-light travel, which introduces the concept of wormholes and the theories of special relativity and quantum mechanics, as well as various envisaged technologies that could allow travel at lightspeed. Next, the author focuses on time travel, explaining the history of scientific research into the subject, the fact that travel into the future is already a reality that the theory of special relativity explains, and the proposed characteristics and issues of technology that allows travel to the past. Part 2 concludes by discussing parallel universes, focusing on the theories that support the existence of other dimensions and universes, as well as the feasibility of confirming those theories and potentially interacting with other universes in the future.

Part 3 (which contains only two chapters) introduces Class 3 impossibilities, which are the only examples of truly impossible technologies and feats because they violate known laws of physics. Kaku explores the impossible technology of perpetual motion machines, explaining advancements in scientific understanding through the vain quest to create a machine capable of producing more energy than it consumes, and the laws of thermodynamics that preclude its existence. Precognition, the ability to see the future, is the subject of the book’s final chapter. Although societies and individuals throughout history have believed in prophecy and the ability to predict the future, Kaku shows how the laws of physics dictate that such a feat is impossible. The book closes with an Epilogue, in which Kaku summarizes the book’s messages and conclusions while reaffirming his futurist perspective that no absolute impossibilities exist in the physical sciences and his belief that future scientific advancements will continue to push the bounds of possibility.