Where do we come from? There are many right answers to this question, and the one you get depends on who you ask. For example, an astrophysicist might say that the chemical components of our bodies were first forged in the nuclear fires of stars. On the other hand, an evolutionary biologist might look at the similarities between our DNA and that of other primates' and conclude we evolved from apes. Lisa Randall, a theoretical physicist at Harvard University, has a different, and novel answer, which she describes in her latest book, "Dark Matter and the Dinosaurs." Randall has written...