If any one of the numbers were different...

Why is There Life? Because, says Britain's Astronomer Royal, you happen to be in the right universe By Brad Lemley DISCOVER Vol. 21 No. 11 November 2000 Discover Magazine Issues nov-00

The Universe is unlikely. Very unlikely. Deeply, shockingly unlikely. "It's quite fantastic," says Martin Rees, Britain's Astronomer Royal, waving a hand through the steam rising from his salmon-and-potato casserole. A casual observer might think the gesture encompasses just this room, the dining hall at King's College in Cambridge, England, where scholars have traded erudite quips for nearly two centuries. Rees digs into his lunch, just as he has dispatched meals here since 1973. In such a clubby, comfortable place, pronouncements about the origin of the cosmos seem a bit overreaching.

But Rees's wrist flick takes in the whole universe, this universe, the one that gave rise to Earth and supports life, from the bristle worms on the ocean's floor to the swallows soaring over the college spires to human beings— including astronomers royal. In his newest book, Just Six Numbers, Rees argues that six numbers underlie the fundamental physical properties of the universe, and that each is the precise value needed to permit life to flourish. In laying out this premise, he joins a long, intellectually daring line of cosmologists and astrophysicists (not to mention philosophers, theologians, and logicians) stretching all the way back to Galileo, who presume to ask: Why are we here?

As Rees puts it, "These six numbers constitute a recipe for the universe." He adds that if any one of the numbers were different "even to the tiniest degree, there would be no stars, no complex elements, no life."The six numbers lurk in the universe's smallest and largest structures. To select one from the small end: The nucleus of a helium atom weighs 99.3 percent as much as the two protons and the two neutrons that fuse to make it. The remaining .7 percent is released mainly as heat. So the fuel that powers the sun— the hydrogen gas at its core— converts .007 of its mass into energy when it fuses into helium. That number is a function of the strength of the force that "glues" together the parts of an atomic nucleus.