You would be right to think this sounds like science fiction or to be skeptical that some of it is even possible. (I’m good with terraforming but doubt that we are nothing but our neurons.) But the strength of Kaku’s writing is knowing which science fiction ideas are worth following. Kaku grounds his readers in science happening right now, while throwing open the windows to imagine where it might lead in a thousand years. In this effort he is particularly adept at drawing from the lexicon of popular science fiction. From Marvel’s Iron Man to Christopher Nolan’s Interstellar, he uses ideas from our shared cultural warehouse as launchpads for questions of the deep future.
...[a] deeply fascinating and energetically written book ... Kaku’s writings have garnered a reputation for combining hard science with clever speculation, and his latest book continues that winning trend. A breathtaking voyage through what is almost certainly the next major period in the history of humanity.
With admirable clarity and ease, Mr. Kaku rehearses the history of rocketry and the formation of the planets, and explains how we might colonize not only Mars but some of the rocky moons of the gas giants Jupiter and Saturn ...The book has an infectious, can-do enthusiasm and is occasionally even a little silly. But since the author covers so much ground—appropriately enough for a book about traveling the universe—no subject can be treated in great depth ... What, meanwhile, does a highly speculative work of popular science such as this one do that a well-researched work of science fiction doesn’t? Mr. Kaku understands SF’s attractions—he introduces chapter topics by mentioning movies (such as Interstellar) or novels (such as Isaac Asimov’s Foundation series). But a lot of modern science fiction is richer than Mr. Kaku’s treatments of his subjects in technical detail as well as in emotional heft.
The problem here is immediately obvious: catch-all 'futurist' label notwithstanding, a theoretical physicist is no more specially qualified to speculate about things like advanced AI or human genetic manipulation than is any teenage science nerd uploading videos to YouTube. There are points in The Future of Humanity where this is unavoidably obvious, and it hurts the book ... His more elaborate speculations in the book's closing chapters are at least connected with Kaku's area of technical expertise, albeit completely unmoored from reality. Fortunately, by this point in his career, Kaku is a practiced and very effective popularizer of science for a general audience; he's unfailingly interesting, with an unerring instinct for the most thought-provoking aspects of his various subjects. The sheer amount of technical scientific speculation in The Future of Humanity is amazing, and yet Kaku is in smooth, perfect control of it the entire time.
Kaku is an international treasure and a man of infectious enthusiasm. You may as well kick an endangered penguin as give one of his books a bad review. But this is a weary, clunkily written and incoherent piece of work. It is hard to know who is supposed to read it ... It is not just boring: it is depressing. Barring a handful of recent discoveries in astronomy, such as dark energy and the observation of 16 possibly habitable planets orbiting distant stars, the book could have been written before many of its potential readers were born ... It hardly helps that the book is stuffed with bizarre sweeping statements and factual mistakes.
Always optimistic and undaunted, Kaku delivers a fascinating and scattershot series of scenarios in which humans overcome current obstacles without violating natural laws to travel the universe. The author digresses regularly into related areas of study, including extrasolar planets, radical life extension, intelligent robots, and the details of settling other worlds ... An exhilarating look at the future.
Kaku wonderfully illuminates possible ways the human race could survive on other planets ... Kaku generally keeps his concepts understandable (one notable exception is his use of string theory in explaining how we could travel to other universes), aided by pop culture references to Star Trek and science fiction novels. Given Kaku’s track record of bestselling popular science books, this work, too, should go far.