He spends the first four chapters of the book setting up some basics about computers which I will (magically) do for you here in one paragraph. Most people are familiar with the notion that computers work with these things called bits, plain old 1s and 0s. These group together into integers (in binary format, but still). There’s an old and well-established area of study concerning the computing power of integers, and the thinking which has reigned for many years is that essentially, all these computers can do the same thing. A person adequately trained could do all the computations on an abacus that a computer could—it’s just a matter of speed and accuracy. Although their powers seem mystical (or damnable) at times, computers are really not all that special. Blam, I saved you 45 minutes.
The book does give a description of what allows quantum computing to be powerful. It adds a new state to the mix: 1+0. This is known as the superposition. A bit can be on, off, or both at once. This is a direct consequence of using sub-atomic particles as switches. He explains why this is useful for the rest of the chapter, but he does it best with one sentence. It means that instead of representing one number with a binary string, let’s say 64 (10000000), you can represent all the numbers from 0 to 64 at one time by having each bit in the superposition. He demonstrates an algorithm for prime factorization which would really kick ass if these things were up and running. It’s not known that factorization is a “hard” problem, though.
One of the reasons that I was excited about quantum computing is the power it might give us to attack problems that are known to be “hard”. There’s a whole family of them, and people with Ph.D. after their names are attacking various problems of this nature. After reading this book, my thinking is that while it’s a strong step forward, we’re still not on the path to being able to solve “hard” problems easily. After all, ternary logic has been possible in silica for some time now. “Is that really all there is to quantum computing?” I’m thinking. I’m sure there’s some subtle point I’m still missing, since very smart people are still working on this. Besides the simple fact that quantum computers are smaller than Gigli’s box office, I can’t really see any advantages any more.
The book also covers material I essentially had no interest in, like how the scientists are actually implementing quantum computers and quantum cryptography. I question why the first is even in a popular science book; what casual reader is interested in implementation details, even if there are five different ones? As for the second, it turns out that there’s a nifty, exploitable property of bits in the superposition which can possibly aid in secure key generation and transmission, which is essentially the entire security problem (as long as you handle the rest of your business, which, trust me, you aren’t.) If you examine a bit in the superposition, it becomes either 1 or 0, but there’s no telling which. (Yet, the physicists will be working on that indefinitely) This helps foil people listening in, via a process explained in more detail in the book.
A Shortcut Through Time is extremely easy to read. I finished it on planes and in airports. It’s an excellent introduction to things like computability, algorithms, and computer science in general for people who have no idea about that kind of stuff, but are interested in computer science. I recommend the book for that audience, but for me, this book is a 6.8/10.