Like many scientists, Harvard professor and theoretical physicist Lisa Randall believes that science has a lot to teach us, and not just about the way the physical world works. Its goal, she says, is to expand the boundaries of knowledge, and what could be better than that? She concedes that her first book, Warped Passages: Unraveling the Mysteries of the Universe's Hidden Dimensions, dealt with esoteric topics—in particular, particle physics, string theory, and cosmology. But her new one, Knocking on Heaven's Door: How Physics and Scientific Thinking Illuminate the Universe and the Modern World (Ecco, Sept.), is different, she jokes, and can be viewed as a prequel to that earlier one, with much more basic information in it.

But lest the curious reader think the going will be easy, it should be said, as Randall does, that her basic questions about science and its importance are discussed in chapters that alternate with pretty technical stuff. "It's really two books in one," Randall says. "One is about physics happening today at the Large Hadron Collider, research in cosmology and attempts to understand dark matter. The second part discusses what science is, what it means to be right or wrong, why uncertainty is good, why risk is important, what creativity can do, and why science is not the same as religion."

Randall, whom Time magazine in 2007 called one of the "100 Most Influential People in the World," says that integrating these chapters—the narrow and the broad—was the most difficult thing about writing the book. "In some ways it was easy," she says, "because it was about a lot of things I wanted to say. But organizing it was challenging. I solved it experimentally, by trying it different ways. I grew as a writer." Cormac McCarthy, a personal friend, went through the book and offered help. "I've had the opportunity to meet amazing people," Randall says. "It was good to get their ideas down so they wouldn't get lost, and to flesh out my own thoughts."

Based on experiences with her first book, Randall believes the interest and ability of the general public is generally underestimated. "A lot of people want to understand physics and have the complete story, though I did encounter basic misconceptions of how science works. Some chapters are in response to what I learned."

Randall is signing galleys of her book today in the autographing area, 1–1:30 p.m., at Table 23.