Superstar physicist Hawking--whose A Brief History of Time (1988) is ensconsed in the Guinness Book of Records for having had the longest bestseller-run in English-language history--returns with 11 essays and one interview, covering matters autobiographical, scientific, and philosophical. The autobiographical pieces share a sketchy, conversational tone and drop a few tasty nuggets: Hawking didn't learn to read until he was eight and proved to be (in the Einstein tradition) a mediocre student; if dropped on a desert island, he would listen to Mozart's Requiem and read Middlemarch. But even so, these pieces keep Hawking's inner life strictly under wraps. Most of the other essays, which tend to repeat themselves, cover the author's major scientific insights: that the universe is "neither created nor destroyed''; that space/time began 15 billion years ago and is finite but boundless, like the surface of a globe. Hawking cites as his "most surprising discovery'' the realization that black holes are not self-enclosed but leak particles and radiation: This leads directly to his most recent enthusiasm, ``baby universes,'' generated by black holes, which branch off from our own universe and sometimes return to it. Sometimes the going is thick ("the N=8 theory has twenty-eight spin-1 particles''), but most of Hawking's arguments will be clear to educated laypeople. His weak suit is philosophy, and, indeed, he includes a mild-mannered attack on professional philosophers, many of whom find his discussions of the big questions--what is creation? does God exist?--to be, as he puts it, "naive and simple-minded.'' No matter: Hawking will be remembered for his physics, not his metaphysics. Not much new, but people feel smarter just by buying a Hawking book. This will sell.