Escape to another universe.

Parallel Worlds: A Journey Through Creation, Higher Demensions, and the Future of the Cosmos by Michio Kaku. Doubleday, 2005. 428 pages. $27.95.

For as long as humans have contemplated the cosmos, we have endeavored, often with great imagination, to foresee our universe's end. According

In his new book, Parallel Worlds, best-selling science writer Michio Kaku uses physics and cosmology to paint a new picture of the end of days: Millions of years after the Earth has been reduced to cinder, the stars, depleted of their hydrogen, will grow dark and cold; the universe will continue its outward expansion; and the cosmos will slowly freeze.

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The only hope for humanity in that scenario would be to escape to another universe or dimension. Science has not yet proven the existence of a parallel universe or dimension, much less contrived a means by which to get there. However, an ever-increasing supply of satellite data now supports the theory of an inflationary universe. In the words of MIT professor Alan Guth, "Inflation pretty much forces the idea of multiple universes upon us."

According to this theory, our universe may have "budded" from a much larger universe, just like the limbs of a tree sprouts from a larger branch. One day, an entirely new universe may bud from our own.

The first step in proving or disproving the existence of multiple universes, Kaku writes, will be to construct a verifiable unified field theory--or a theory that explains the various types of movement in the known universe, reconciling Einstein's equations with Newton's. Dimension jumping will remain science fiction for at least the next millennium, Kaku says, but the discovery of a unified field theory will probably occur within our lifetime.

Once a unified theory has been formulated, it will drastically alter the course of science. Suddenly, we will look toward distant galaxies not merely as unreachable collections of stars but as truly conquerable frontiers. Unified field theory, combined with some yet-inconceivable innovations in engineering, will allow humankind to probe and even build black holes, compress space, or even escape our dying universe.

"The unified field theory," Kaku writes, "instead of being a useless but elegant curiosity, may ultimately provide the blueprint for the survival of intelligent life in the universe."

Kaku explores the near future as well as the far. In the coming decades, he writes, scientists may conduct experiments with huge gravity wave detectors based in space and send combination solar and ion-powered probes to nearby stars.

"We are making the historic transition from being passive observers to the dance of nature to becoming choreographers of that dance ... with the ability to manipulate life, matter, and intelligence."

Kaku reminds readers that, while some of his predictions look millions of years into the future, they are relevant today. "Decisions made by us will reverberate throughout the century. How we resolve global wars, proliferating nuclear weapons, and sectarian and ethnic strife will either lay or destroy the foundations of a [new] civilization."

Indeed, of all the compelling ideas expressed in Parallel Worlds, the most radical is perhaps the most obvious: that we, as a species, share a common destiny and that, the sooner we embrace that concept, the greater a future we shall share.