Over the course of the last two weeks or so I’ve forayed into reading popular science books on physics for the first time. Namely, I read A Brief History of Time by Stephen Hawking and then The Fabric of the Cosmos by Brian Greene. Both dealt with relativity, quantum and particle physics, and cosmology. Greene’s book went further, introducing the “time’s arrow” concept and also discussing superstring theory and ending with some speculations on the future of physics research (a few up-and-coming experiments, and teleportation, wormholes, and time travel).
Overall, I think that Greene is a better writer. Both authors are respected physicists at the forefront of their profession, although I think there is no doubt that Hawking is in a class of his own. Despite superior intelligence, this detracts from Hawking’s writing since he seems extremely eager to highlight his own discoveries, relevant as they are, in order to give himself credit. Greene does mention his own work but he comes off as much less intimidating to the reader. Even with ideas that he himself labels difficult to explain without the math, he comes off as lucid and easy to understand. I was also thankful for extensive endnotes which gave fuller explanations to advanced or “mathematically inclined” readers, as well as pointers to further reading.
However, certain things detract from the Greene book as well. For one, he really loves analogies involving The Simpsons or The X-Files, which get kind of “lame” after a while. The elephant in the room is also, of course, string theory. Although he gives quite a fair account of both sides of the string theory debate, he should not take up 100 pages discussing the topic.
For readers unfamiliar with the controversy surrounding string theory, the problem is this – in the last century physicists have come up with two major frameworks for deviations from classical Newtonian mechanics – quantum physics to describe the very small (sub-atomic) and general relativity to describe the very massive and very fast (within an order of magnitude of the speed of light). However, as classical mechanics are now shown to be invalid theoretically but very good approximations of “mid-sized” phenomena, it isn’t clear where quantum physics and relativity should meet. Combining the equations from the two theories yields nonsense. However, superstring theory, which suggests that sub-atomic particles are made up of vibrating one-dimensional superstrings, which are made up of pure energy, successfully combines the theories, and is the first framework to do so.
The problem is the conflict of superstring theory with the science-philosophical subfield of confirmation theory. According to the scientific method, roughly summarizing, observation should yield hypotheses that predict the possibility and impossibility of certain phenomena, which can then be tested for using experiments. At this point, superstring theory eludes any kind of empirical measurement. The other problem is that the equations have been massaged extremely rigorously so that while they conform data now, they were initially off by several orders of magnitude. Whoops. There are issues with changing your hypothesis part of the way through – that’s violating the scientific method. And the biggest problem is that with each update to the theory, spatial dimensions are seemingly arbitrarily added for the equations to work. Hmmm.
Overall, Greene, who is a leading string theorist, has gotten kind of a bad rap in the physics community for his enthusiasm. Just look at this xkcd:
Well, that’s what you get for committing to something like that. Good luck, Brian. In any case, if you’re a layperson who wants to learn about theoretical physics, I definitely recommend Greene (The Elegant Universe was a Pulitzer finalist), but don’t pay too much attention to the string theory stuff.