A Down To Earth Guide To The Cosmos


Our Universe and Others

By Martin Rees

Addison-Wesley 291pp $25

How's this for the ultimate catastrophe? Two-thirds of the way through his new book on the origins of stars, galaxies, and the universe, Sir Martin Rees raises the startling possibility that physicists could destroy the cosmos. The idea goes like this: Researchers are building ever more powerful particle accelerators, intended to produce collisions of subatomic particles to probe the deepest mysteries of matter. A jolt of energy from one of those collisions might touch off a dramatic "phase transition" in a tiny spot in space. That could create a "bubble" that would "expand at the speed of light...until it engulfed our entire universe," writes Rees, Britain's Astronomer Royal and a longtime Cambridge University cosmologist. So, Rees wonders, "is there a risk that the next generation of machines could inadvertently tear the fabric of space?"

Fortunately, Rees goes on to describe how his calculations have proved that the risk--if it exists at all--must be small. But it's just one of many provocative ideas in Before the Beginning, Rees's exploration of our beautiful and bizarre universe. With a hint of dry humor, a knack for apt descriptions, and a refreshing candor about the limitations of science, the Cambridge don proves an engaging guide. For instance, he captures the romance of the quest with this quote from Belgian priest and scientist Georges Lemaitre: "Standing on a well-chilled cinder, we see the fading of the suns, and try to recall the vanished brilliance of the origin of the worlds."

Rees first takes us on a trip through the most important discoveries about the stars. He states that "astronomy was the first `professional' science." Indeed, as far back as the 16th century, astronomer "Tycho Brahe's project to map the stars was bankrolled so lavishly by the Danish monarch that he could build a cathedral-like observatory...on the island of Hven." But it wasn't until this century that scientists figured out that the elements that make up the earth--and that make life possible--were forged in fiery explosions of ancient stars. As Rees puts it: "We are stardust--the ashes of long-dead stars."

The supernovas that created the building blocks of our world aren't the only strange denizens of the cosmos, however. There are still-mysterious quasars and incredibly dense neutron stars, whose gravity is so strong "that more energy would be expended in climbing a millimeter mountain on a neutron star than in escaping completely from the Earth," Rees writes. Interestingly, scientists have rarely been able to predict what they'll find next. He admits that "most discoveries have surprised theorists, and initially perplexed them."

That hasn't fazed the theorists, though. Rees wryly cites the observation of physicist Lev Landau that cosmologists are "often in error but never in doubt." And now, physicists' theories predict even more bizarre phenomena, things such as unthinkably heavy black holes smaller than a single atom or magnetic monopoles, whose cores would "be a tiny sample of what the universe was like when it was 10-36 seconds old," Rees writes. Or how about cosmic strings? They are "thinner than an atomic nucleus but so heavy that their gravity could have triggered galaxy formation." What's more, a person or object hit by such a string would suffer a grim fate. Its "two halves [would be] squashed into each other at supersonic speed," the book warns.

Fortunately, that doesn't seem to happen very often. In fact, many of these exotic cosmic beasts might not even exist. Rees admits that humanity is far short of understanding the universe and its origins. For instance, he points out that "to our embarrassment, 90 percent of every galaxy is unaccounted for." That's because all the observable stars make up only some 10% of the amount of mass that scientists believe must exist. So what is this mysterious "dark matter"? Scientists have fingered everything from dark neutron stars or black holes to tiny particles called neutrinos. Rees favors the notion of exotic particles, rather than ordinary atoms. But don't take the word of any scientist as gospel, he cautions. "Journalists sometimes need to assess scientists' claims with as much skepticism as they customarily bring to those of politicians," he writes.

Of course, this doesn't stop Rees from pushing his own provocative claim--that our universe may be only one of many. Many black holes, for instance, may spawn entirely new universes. As a result, "countless others may exist in which the laws are different," Rees writes. "This new concept is, potentially, as drastic an enlargement of our cosmic perspective as the shift from pre-Copernican ideas to the realization that the Earth is orbiting a typical star on the edge of the Milky Way." I wish that Rees had explored the profound implications of this idea, but perhaps he was right to steer clear. As he observes, "scientists' incursions into theology or philosophy can be embarrassingly naive or dogmatic."

Remember A Brief History of Time, the 1988 best-seller from Rees's famous colleague Stephen Hawking? Many bought it, but few read it. Rees's book, by contrast, is one that even the cosmologically illiterate will be able to understand. It may not measure up to the best tome on cosmology: journalist Dennis Overbye's wonderful Lonely Hearts of the Cosmos. But it can lift your mind from its mundane worries to contemplation of the deepest mysteries of our existence.

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