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Cosmic Question

Will the Universe Go Crunch, or Will 'Dark Energy' Rip It Apart? Either Way, Your Head Will Pop.

By Joel Achenbach
Washington Post Staff Writer
Sunday, November 21, 2004; Page D01

They say academic arguments are so vicious because the stakes are so low, but Andrei Linde and Paul Steinhardt are arguing about something huge, something truly cosmic: the fate of the universe.

Linde and Steinhardt are two of the premier cosmologists of America and, as far as we know, of this sector of the Milky Way galaxy. They study the origin, structure and destiny of the universe, all the classic 3-in-the-morning dorm-room questions that threaten to blow your mind. How big is the universe? Is it infinite or finite, and if it's finite, where's the edge? How did it begin? What will happen to it? Why does anything exist at all?

There's a story there, written in starlight: The deepest portrait of the universe ever recorded, by a Hubble camera. (Nasa Via Reuters)

Linde, a Stanford professor, Russian-born, theatrical (he performs magic tricks and acrobatics in his spare time), warned two years ago that the universe might collapse in as little as 11 billion years. Recently he revised his prediction, saying that the end might not come for at least 24 billion years. "Cosmic doomsday delayed" reported one online science journal earlier this month, throwing a sop to Democrats desperate for good news.

Regardless of the timing, The End as Linde sees it would prove to be extremely fatal to any living thing. Linde says the entire cosmos will begin to contract, the galaxies rushing back toward one another, space itself heating up, our oceans boiling off, Earthlife frying, until everything slams together in a cataclysmic Big Crunch, all matter and energy, and indeed time and space itself, compressed into an infinitely dense black hole.

"All these galaxies will crash into each other, and the sky will be shining in blue light, ultraviolet, then X-ray; the temperature will be very large and everything will be just evaporated," Linde says.

He isn't panicking. He speaks with a serenity that comes from knowing that this bad stuff is a long ways away. He says, reassuringly, "Mankind will find many ways of killing itself much earlier."

But now comes Steinhardt, a Princeton professor, with a scenario that is just the slightest bit sunnier. He suggests that our universe may be just one of two universes, or "branes," that periodically collide. These two branes, Steinhardt hypothesizes, have been bouncing off one another for untold billions of years. The next time the invisible brane comes crashing back into our universe, we'll see the laws of physics start to change.

Physical "constants" will cease being constant. Gravity will strengthen (apples falling from trees will hit the ground faster). The universe will collapse, as in the Linde scenario -- "Unless we found a way of protecting ourselves, we would be evaporated in the crash between these branes," Steinhardt says -- but there's good news at his version of The End. There's a bounce! The whole enterprise begins expanding again, inflating, and becoming once again a universe that is sufficiently comfortable to permit people to wear shorts and T-shirts.

Here is what Steinhardt says of Linde: "He will tell you many things depending on which day you catch him."

Linde on Steinhardt's bouncing branes: "Oh my God. Oh my God." (Deep breath.) "It is a very interesting but a very wild speculation. . . . It's not science."

The two men don't exactly rage at one another, but in phone interviews each makes it clear he finds the other irritating and unpersuasive.

Every cosmologist would like to become known as the person who figured out the destiny of the universe, but the facts are sparse and ambiguous. Cosmologists tend to do a fair bit of arm waving. You get the feeling that a clever scientist could prove on paper that the universe is made of cheese.

At some level it's the ultimate esoteric topic. Our lives are lived in a certain slice of space-time, so narrow that it really doesn't matter in any practical sense whether the universe will expand or contract or contract-and-bounce. But we also wouldn't be human if we didn't try to decode the universe. There's a story there, written in starlight.

Cosmologists are rambunctiously creative, painting pictures that inspire their colleagues to engage in furious art criticism. There are art movements, and splinter groups, and mavericks. Someday the current fascination with string theory, for example (you know: the universe is made of very tiny strings that vibrate at different frequencies), might be viewed as something lovely but a bit beside the point, like Picasso's blue period.

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