Surprise! Our little corner of the universe is even smaller than we thought.

By Bruce Sterling

Since the days of Galileo's telescope, new and better scientific instruments have steadily transformed our conception of the universe. Now we've got the Wilkinson Microwave Anisotropy Probe. This superb gizmo, launched in June 2001, is floating 1 million miles from Earth in the second Lagrange Point, measuring the density of the universe with unheard-of digital accuracy and sending data back to mission control.

Already, the probe's findings have provided a few salient new notions about the nature of cosmic reality. For starters, the universe is 13.7 billion years old. Unlike previous figures, this is not a rough estimate; the margin of error is about 1 percent. In addition, the universe is flat. Forget all that mind-boggling space-time-is-curved stuff. Euclid was right all along. And the space-time pancake will expand infinitely. There's no such thing as an end to this particular universe.


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Now here's the really wacky part:Everything we're made of or can measure - from atoms to energy - is only 4 percent of the whole shebang. The rest is dark matter (about 23 percent) and, best of all, dark energy (73 percent).

Although it has been overlooked amid the recent military ruckus, the Wilkinson probe has given the 21st century a brand-new cosmology. Such intellectual upgrades nearly always begin by debunking humans in some obscure but potent way. The Copernican revolution revealed that Earth was not the center of the cosmos. Newtonian physics proved that the planets move according to lifeless clockwork rules instead of majestic divine will. Einsteinian relativity showed us that the cosmos lacks absolute values; it all depends on how things are measured, by whom, and under what circumstances.

The new cosmology is very much of that order. Everything we can see or touch, everything material and physical, is mere fat in the cosmic milk. Everything we thought was important is a tiny fraction of what's really going on.

It gets worse. Dark matter, the 23 percent formerly thought to be burnt-out stars and lonely little planetoids, probably has nothing to do with normal, so-called baryonic matter. It might be axions and neutralinos, leftover twiddly bits predicted by string theory. Or it might be what physicists call weakly interactive massive particles, or WIMPs, which form a kind of cosmic smog that builds up in the wake of nuclear interactions. We'll never be able to touch this stuff. We can't build things with it, sell it, or put logos on it. It's not our kind of stuff - unless planet Earth should happen to wander through a thick wad of it. A dense cloud of WIMPs would likely cause the center of the planet to boil. And forget about shielding yourself from a dark matter mishap with mere baryonic matter like, say, lead. The physics don't work that way.

But even incineration by WIMPs doesn't compare with the fantastic thought that three-quarters of everything is dark energy. This mysterious stuff pushes the universe apart. It forces the cosmos to expand. This is not the steady state model of Einstein's heyday, when the universe was static and conservative. It's not even the jazzy big bang model, where everything blew up way back in the beginning. We denizens of the 21st century live in a steady bang. The bang never went away - in fact, our natural habitat is bang. Three-quarters of the universe is dedicated to pushing itself open. It's a gigantic heaving that has worked from the first primal instants and always will. It's the very nature of space to expand.

Human societies are always reshaped by their concepts of the basic nature of the universe. Copernicus damaged the infallibility of the church; Newton laid the foundation for the Enlightenment; Einstein spurred moral relativism. What will we make of our new knowledge? Are there political implications to the idea that most of the universe is untouchable, endlessly expanding, scarcely knowable? Will we finally get over our obsession with static utopias, sudden armageddons, limits, and closure? Is there philosophical comfort to be found in a silent, never-ending steady bang?

There's one more thing to consider: What will it take to get our atom-smashing mitts on some dark energy? This stuff is the fountainhead of the universe. It makes Iraqi oil look like a dust mote. The 21st century offers us a new quest. Dark energy is irresistible.

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