I like Michio Kaku. It's amazing that someone as intelligent and lost in the world of physics and mathematics to co-create something as complicated as string field theory can write lay science books that are interesting, relevant and funny. In this book, Kaku uses science fiction to explore the realms of physics and as a jumping-off point for the discussion of theoretical physics. A sucker for science fiction myself, I found Kaku's discussions enlightening and heartening. Kaku is an optimist with a firm belief in human progress and has a way of reaching to the kid in all of us by showing how marvels such as teleportation, interstellar travel and time travel are perfectly acceptable in the realm of modern physics. He is also very careful to caution us by giving realistic timetables for humanity's ability to harness and create such fabulous inventions.
Kaku divides all of his discussions on the "impossible" into three categories:
Class I impossibilities: Things that do not violate the known laws of physics, but require a technological leap in our capacity to manipulate energy. These impossibilities have a strong chance of becoming reality by at the latest, the end of the century.
Class II impossibilities: Things that do not violate the known laws of physics but are impossible for our level of civilization (his categorization of types of civilizations classified by their use of energy is interesting in its own right). These things may become possible if we make the leap from a type 0 civilization to a type 1 civilization (more on this below).
Class III impossibilities: Things that violate known laws of physics, but that may be possible if we expand our knowledge and find ways to create conditions or environments that violate these laws and create new ones (sounds crazy, but Kaku insists this would be possible for a type 3 civilization).
Before I forget, Kaku explains (based on the work of noted physicist Freeman Dyson) we are a type 0 civilization because we use dead plant and animal matter as our chief source of energy, which is extremely limited and inefficient. A type 1 civilization has mastered terrestrial energy - they can manipulate the weather, mine the oceans and tap energy at the core of their planet. A type 2 civilization has mastered stellar energy - their energy consumption is so vast they need to extract it from a star. A type 3 civilization are galactic, they consume and can manipulate the energy of multiple stars in multiple solar systems. We are on the verge of breaking through to a type 1 civilization. Depressing right? The leap between levels of civilizations, however, is predicted to occur at faster and faster rates, much like computer speeds doubling and doubling where growth becomes exponential. The hardest part is starting out. ;)
Anyway, the most interesting thing is that most of the bizarre and seemingly magical technology discussed in Physics of the Impossible Kaku classifies as Class 1 impossibilities. As crazy as it may sound, teleportation, cloaking devices, robots and the harnessing of anti-matter are all possible by the end of the century. This is more than wishful thinking. Kaku presents sound science to back up his claims, which is enormously exciting and makes me anxious for the future.
Sadly, things like faster-than-light interstellar travel and time travel are class 2 impossibilities that we will never see in our lifetimes.
A great book for the kid in all of us, and a sound introduction to the world of theoretical physics for all people.