Cosmology: A Very Short IntroductionPeter Coles
Oxford University Press
This was the third and best of the astronomy-related Very Short Introductions I have read for my International Year of Astronomy Reading Challenge. Cosmology: A Very Short Introduction is well written and organized, and treats extremely difficult subjects in a very down to earth and sometimes humorous way. Relativity, particle physics, quantum mechanics, and the Big Bang are all presented in a way anyone can understand and see how they relate to cosmology, without getting into all the nasty mathematics. But Peter Coles does more than explain the science of cosmology—the search to understand the nature, origins, and fate of the universe—he also shares some of the journeys science has taken towards understanding the universe. He shows how discoveries are built, one upon the other, how work in disparate fields can be brought together to find answers, and how the work of some scientists can be lost and forgotten, or recovered and brought forward. When he reaches the limits of knowledge, he doesn’t stop but describes some of the theories competing to make the next step forward. That makes this an excellent book not just for teaching some basics of cosmology, but also teaching how science works.
There is just one little problem with this otherwise excellent book: it is out of date. In the mere 8 years since it was published, cosmologists have made phenomenal progress in substantiating some of the theories that Coles presents as mere possible alternatives. For instance we now know what the Universe is made of: 4% “baryonic” matter, of which we are made; 23% cold dark matter, which doesn’t do much other than gravitate; and 73% dark energy, which seems to gravitate in reverse. This adds up to a Universe that is geometrically “flat,” a concept that is difficult to explain but absolutely fundamental to cosmology. Most people have also heard by now that the Universe is expanding, and at an ever-increasing rate—thanks to dark energy. That answers another major question in cosmology, and has reduced the age of the Universe from an estimate of 15 billion years when this book was written to about 13.7 billion years.
The reason I know all this is because I had already read Galaxies: A Very Short Introduction, which describes these great discoveries at some length. At the time I criticized the book for straying off topic, but now I am glad of it because I might not have known about them otherwise. I don’t think I can overstate the importance of these discoveries—it is a privilege to be alive at a time when a picture of the whole universe, from beginning to end, is starting to come together. There is still the problem of the initial state of the Big Bang—as far as our theories can tell, it was a time (if time even existed then) of infinite density and infinite temperature, which is impossible—not to mention trying to figure out what the heck cold dark matter and dark energy are. But knowing the fundamental properties of the Universe—the “ΛCDM” or “standard” model—is, as the author of Galaxies puts it, “one of the great triumphs of science.” Hurrah for humans!
I would still recommend reading this book, but I would read it with, and before, Galaxies. The two books complement each other well, and by reading Cosmology first you set up a delicious mystery that gets solved, at least partially, in Galaxies. The two books together are a wild ride through all that is. I can only hope that both of them will soon be obsolete as we discover more about this amazing Universe of ours.