OUR COSMIC HABITAT

Einstein once asked whether God could have made the world any differently; here, Rees, England’s Astronomer Royal, offers an answer.

Originally delivered as a series of lectures at Princeton, Rees’s meditations on the origins of the universe and the laws of physics begin with the planets and stars that make up the visible universe. While Giordiano Bruno and other philosophers speculated that distant worlds might be as hospitable to life as ours is, only in the last decade has science begun to detect planets beyond the solar system. Scientists who argue that life is the inevitable product of commonplace physical conditions have little better evidence on their side than those who believe it to be a rare cosmic fluke. What they do agree on is the general uniformity of physical laws throughout the observable universe. Gravity pulls at the same strength, and the relative masses and charges of the elementary particles remain constant. All this can be accounted for by a single creation event, popularly known as the Big Bang. Radio astronomy has given theorists a good idea of what conditions were like only a fraction of a second after the Bang. But theory cannot account for certain apparently arbitrary parameters, such as the relative abundances of matter and antimatter, or the comparative strengths of the different forces that act on all matter. What would happen if these parameters were different? Could there exist universes in which they are in fact different? Rees (Before the Beginning, 1997) suggests that other “bubbles” of reality might exist in unreachable dimensions, each with its own physical laws. Nor are these alternate universes necessarily beyond the reach of science; interesting theories prompt scientists to find ways to test them, and the future promises to be every bit as interesting as the past.

A provocative survey of modern cosmology for readers who want the big picture.