Physics Of The Impossible by Michio Kaku
I began reading this book with the expectation that Michio Kaku tends to be among those physicists who are more optimistic about what science will allow humans to do in the future – and he would be rather generous with what technologies he considered possible.
When not discussing specific scientific matters he may give a quote like "Anything that is not forbidden is mandatory.” I dislike such claims. They can’t really be proven [at least until the statement is unnecessary because we know everything]. The claim is meaningless unless we know exactly what is “forbidden”, rather than the closest approximation science currently has – so even if true, we can’t really apply it today. Kaku also likes to quote scientists of the past claiming something is impossible - things we know today are possible. Yes, scientists can make mistakes. But that doesn’t mean because Kaku claims perpetual motion machines are impossible ipso facto they are possible. One could as easily collect a list of quotes of scientists claiming they'd discovered cold fusion and other mistaken claims and try to imply that shows that things today's science considers to be impossible will always be impossible. Such quotes don't prove anything.
However, when Kaku is getting into specific science and technology I did not have as strong an impression of wishful thinking. When he was hopeful that science would overcome issues currently limiting advances, he didn’t necessarily come across as certain it would happen. Depending on the scientific issues, he indicates whether it is more plausible we would develop a particular technology in the relatively short term, the relatively long term or not at all.
Part 1: Class I Impossibilities
1) Force fields
This is one of the cases where Kaku presents a way future science might be able to provide the same service as something in science fiction, but the means to do so doesn’t resemble what is portrayed in SF.
His first suggestion is to have 3 layers: The outer layer is a very high temperature plasma shaped by electromagnetic fields, the middle layer: is a grid of laser beams, and the inner layer: nanotubes (with photochromatic qualities to stop laser beams). He argues the lasers will destroy objects that get through the plasma. For the lasers in the middle layer to form a grid of crossing beams, I'd think the laser projectors would have to be between the inner and outer layers, which could mean that anything getting through the plasma layer could potentially hit the laser projectors and damage them. Presumably, if your enemy understood how this worked, they would attempt to aim to damage the laser projectors. Kaku doesn’t clarify whether or not my assumptions on this are true.
Kaku doesn't indicate how this would work in practice. That is, suppose you have a structure on a planet or a spaceship in the void. Suppose you don't want the "force field" on all the time (either because of energy expenditure or to allow entry and exit when protection isn't needed). The outer layer of your "force field" is an ultra-hot plasma (sort of a very hot gas of ions). Where are these ions when the "force field" is off, and how long does it take to re-activate it? The middle layer is the laser beam grid. When the "force field" is off, do the laser projectors remain outside beyond the nanotube layer? How long does it take to re-position and/or start them all firing again? The inner layer is nanotubes capable of great strength. Is this a solid barrier? Does it have to be altered to allow entry & exit? What is involved in altering it and how long does it take? Kaku does not explicitly say whether he imagines the nanotube layer would also be the photochromatic layer to stop laser beams or whether the photochromatic layer is a fourth layer. The photochromatic layer seems to require the laser beam to enter the photochromatic substance - that is, it can't be like a window screen where some process occurs when a beam goes thru a hole. I would think it has to be a solid (even if paper thin) layer. How do you allow entry and exit, how long does it take to alter?
Kaku’s “force field” is not only conceptually different in that it is composed of three layers of entirely different defenses, the activation and deactivation of it seems to have practical differences from force fields in SF. Force fields in SF tend to be immaterial (almost supernatural) phenomena that (in a sloppy science way) seem to fit the phrase “force field”. However, there are no forces of nature that generate fields like those in SF. Kaku’s solution uses actual material means – and is thereby possible, but as a result “force field” doesn’t seem to be a fitting label.
Kaku’s solution may have a resemblance to some kinds of invisibility in fiction, but not others. The possibility of “invisibility” depends most likely on “metamaterials”. These are artificial materials with tiny light-bending pieces embedded in it. That being the case, a human body itself doesn’t seem to have the potential to make itself invisible. Surrounding a human with an enclosure of metamaterials might make the human invisible.
Metamaterials are a recent discovery. So far, they can’t make anything “invisible” as we usually use the term. The embedded light-bending pieces can only bend the light of a certain color (wavelength). There is currently no solution for making an object invisible in all colors / wavelengths other than to have a series of different layers each of which handles a different color. There are other issues which also must be resolved before we can make objects fully invisible. For instance, it’s easier to get metamaterials to work in two dimensions rather than three. Flexibility is an issue. The embedded pieces must be smaller than the wavelength to be bent – and scientists have not yet been able to make embedded pieces small enough to handle some colors. The size of some wavelengths is so small it might not be possible to have enough atoms to bend the light well enough. So, there are currently no conditions under which we can make any kind of object invisible for all colors. Doing so for three dimensional, flexible, moving objects face more challenges.
Also, unlike fictional invisibility, complete invisibility by this method wouldn’t permit a person to look out. If all the light is bent around the person to maintain a perfect illusion, no light reaches the person’s eyes. If you don’t bend all the light so the person can see, the illusion is less than perfect.
Kaku also mentions speculation about using holography or higher dimensions to provide invisibility. These ideas are even less developed than metamaterials.
3) Phasers & Death Stars
Current research on “quantum teleportation” is largely related to efforts to develop quantum computers. Therefore, there is some discussion of quantum computing as well as the possibility of transmitting descriptions of particles or atoms for duplication elsewhere.
Kaku discusses how devices may be able to detect brain activity and associate it with certain kinds of mental activity. The interpretation can be indirect. For instance, activity in a certain area of the brain may often be associated with lying, but that brain activity is not specifically activity that can only be lying.
It may be possible to associate some brain activity with a person thinking a certain concept. In that sense, thinking of some concepts might be identified and word equivalents transmitted to others. It’s not clear how many concepts might be identifiable from brain activity. Kaku indicates it’s unlikely complete and detailed translations will become possible.
It may be possible to stimulate specific parts of a person’s brain in order to give them a message, but probably not detailed messages conveying specifics.
Unlike telepathy in fiction, the possibilities Kaku discuss involve technology and limited mental control over the process.
This is another case where Kaku’s solution bares little resemble to fictional telekinesis. The premise is that if devices could interpret brain activity (as in the section above) a person might be able to convey a command to a computer by concentrating on some idea. If a computer could figure out what you wanted based on scanning your brain activity, the computer could then instruct other devices to carry out a task. A person would think and as a result a specific activity would occur. One might understand why some people would label this “psychokinesis”, but this is not the “mental powers” directly influencing the world that one finds in fiction.
8) Extraterrestrial life & UFOs
10) Antimatter & anti-universes
Part 2: Class II Impossibilities
Kaku suggests the energy needed to make a short-cut by open a hole in space-time is far too vast for our civilization, but may be possible for a Type III (galactic) civilization. It made me wonder: if we need to make such holes in order to allow travel and communications to create and maintain a galactic civilization, how will we get the galactic civilization necessary to make the hole?
12) Time travel
13) Parallel universes
Part 3: Class III Impossibilities
14) Perpetual motion machines