Superstring theory has been called "a part of 21st-century physics that fell by chance into the 20th century." In other words, it isn't all worked out yet. Despite the uncertainties--"string theorists work to find approximate solutions to approximate equations"--Greene gives a tour of string theory solid enough to satisfy the scientifically literate.
Though Ed Witten of the Institute for Advanced Study is in many ways the human hero of The Elegant Universe, it is not a human-side-of-physics story. Greene's focus throughout is the science, and he gives the nonspecialist at least an illusion of understanding--or the sense of knowing what it is that you don't know. And that is traditionally the first step on the road to knowledge. --Mary Ellen Curtin