Anthony Zee is a distinguished particle physicist who presently holds joint appointments at the University of California and the Institute for Theoretical Physics at Santa Barbara. In Fearful Symmetry he has written a sprightly, partisan history of 20th century physics that bright students will enjoy immensely. Zee does not deal with all of 20th century physics. He is concerned solely with the physicist's search for beauty, which, to his eyes, means one and only one thing—the quest for symmetry in nature.
Throughout the book, Zee takes the point of view of an artist: "Let us worry about beauty first, and truth will take care of itself." He argues that the demand that nature be symmetrical has led to the most successful theories. "Symmetrical" in physics has a particular meaning that is not too distant from that implied when an artist or architect uses the term. A physicist will say, for instance, that the laws of physics are rotationally invariant. By this he means that they do not pick out a preferred direction in space. As an analogy, one can think of the rotational symmetry of a circle; any point is indistinguishable from any other point. Another example is parity invariance—the laws of physics should be unchanged in a world that is a mirror image of ours.
However, by 1957 experiments showed that nature does not respect parity invariance. That is, the mirror image of our world does not behave exactly like the one we have. Almost, but not quite. And here lies Zee's Achilles' heel, for anyone who wishes to exploit it. Time and time again physicists have produced symmetric theories and time and time again nature has turned out to be almost—but not quite—symmetric. Into their theories scientists must introduce mechanisms to break the very symmetry they have set out to establish. Many of these symmetric the ories are also ridden with infinities that must be removed by a process called renormalization. Zee finds such theories beautiful, but I believe Richard Feynman called the re-normalization procedure "a sleaze." (I have often wondered if perhaps we need something other than groups—the mathematical tool used to construct symmetric theories—that takes care of the universe's approximate symmetry in a more natural way.)
Zee would undoubtedly agree that the state of affairs is not perfect and he acknowledges that an absolutely symmetric universe would be a very dull place: one type of particle, one type of interaction, no life, no theories. There is some balance to be struck between unity and diversity. Does this mean we should abandon the search for symmetry? Zee tells us not to lose heart; the burning "tyger" will lead the way to Truth. Readers will en joy staking out their own positions, as Zee does his. And there is room for many points of view. In fact, by book's end, one detects a sigh; maybe even Zee thinks supersymmetric and superstring theories have taken symmetry a step too far.
Although the book is suitable for bright high school or college students, even physicists will learn a few things. Zee's approach is basically non-mathematical. There are, however, a few chapters on group theory and representations that some readers may find tough going, even more so if they know anything about groups and representations; the examples of gluing red and yel low "entities" together serve to confuse more than enlighten.
If I have any further quibbles it is that the tone, light throughout, veers a little too much towards "gee-whiz and golly" and hero worship of Einstein. However, these are quibbles; the whole thing is done with such infectious enthusiasm that one can't help but smile and want to meet the author.