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Praise for Endless Universe

From Los Angeles Times Sunday Book Review by George Johnson
Outside the Great Gate of Trinity College, Cambridge, is a tree reputed to be descended from the one that dropped the apple on Isaac Newton's head. The result of the concussion, the legend goes, was Newton's law of universal gravitation: The same force that pulls things to Earth also binds the planets around the sun. So began an era of cosmic mergers and acquisitions that led, three centuries later, to Stephen Hawking's famous prediction that the end of physics -- the Theory of Everything -- was in sight.

Hawking, as his press agents never tire of reminding us, holds Newton's old chair as Lucasian Professor of Mathematics at Cambridge University. By the time he assumed the post, an all-encompassing physics indeed seemed at hand. Electricity had been united with magnetism, and electromagnetism with the weak force that causes nuclear decays. For their next act, physicists planned to combine this electroweak force with the strong nuclear force that glues quarks together. That would still leave gravity, but Hawking bet, in his inaugural Lucasian lecture in April 1980, that by the year 2000 it too would be absorbed into the mix. All these fundamental forces would be reduced to facets of a single phenomenon -- supergravity -- present at the moment of creation.

Sitting in the audience that day was a graduate student, Neil Turok, who went on to get a PhD in theoretical physics. He didn't suspect at the time that he would be swept up by another convergence -- between his newly chosen field and cosmology.

It was a natural connection: Testing an idea like supergravity required a particle accelerator literally the size of the universe -- and the "experiment" had already been done: In the searing temperatures of the Big Bang, all the forces would still have been fused together. Figure out the Bang and you could reverse-engineer the Theory of Everything.

That's not how things turned out. In "Endless Universe: Beyond the Big Bang," Turok and Paul J. Steinhardt, a Princeton physicist, describe how they devoted years to the quest, only to find themselves veering from the pack with a new theory -- a radical model of the universe in which there is no beginning explosion but, rather, an endless cycle of cosmic thunderclaps.

Part of the book's appeal is the way it intertwines the two scientists' stories. Around the time Turok is listening to Hawking's Lucasian lecture, we see Steinhardt, then a junior fellow at Harvard, trying to make sense of a seminar he'd just heard by Alan Guth, who was putting forth a wild idea called cosmological inflation, a modification of the Big Bang.

Unadorned, the Big Bang theory has trouble explaining some striking features of the universe, like why it is smooth instead of lumpy: To us, the starry sky may appear disorderly, but from a god's-eye view matter is distributed, for no obvious reason, more or less homogeneously. Guth proposed that an early burst of breakneck expansion, lasting a tiny fraction of a second, had straightened out the kinks. Inflation also promised to explain why the universe seems to have a mostly uniform temperature and why its overall geometry is "flat" and not curved.

Guth's idea needed some work, and Steinhardt became one of its principal architects. Turok and others also made brane to stretch, giving rise to what we, on our brane, see as the cosmic expansion.

The most revolutionary part of the theory was still to come. In the standard Big Bang model, the stretching of space goes on forever, but Steinhardt and Turok's model is cyclical. Expansion is followed by collapse followed by expansion, ad infinitum, as the branes repeatedly slap together and fly apart.

Steinhardt and Turok are not the first scientists to try to find a popular audience for an ambitious idea still (and perhaps forever) on the fringe of science. It's a hard trick to pull off.

You might think readers attracted by the notion of an alternative to the Big Bang would already have a pretty good idea of what the Big Bang is. But the authors make no such assumption. Attempting to reach as wide an audience as possible, they start from scratch, with mini-crash courses on quantum mechanics, special and general relativity, the history of cosmology and even superstring theory -- all in preparation for presenting their minority report. I was glad for the clear reminders about things I'd read and forgotten, but I couldn't shake the feeling that they didn't quite know their audience -- and that they were writing the book too soon.

The authors make a good case that their theory can account just as well as inflation does for recent observations -- like the precise measurements of the universe's background radiation by the Wilkinson Microwave Anisotropy Probe -- and without so much filigree (unless you count all those strings and branes). And they promise to avoid the question of what came before the Big Bang. In the standard cosmology, matter and energy, along with space and time, seem to emerge out of nowhere. In the cyclic model, these ingredients are there all along, recycled as the great wheel turns.

Ah, but where did the wheel itself come from? For now, we'll have to leave that to scientists on some other brane.

Copyright © Los Angeles Times. All rights reserved


From Publishers Weekly
As has happened many times in the history of science, just when we finally are able to cozy up to an idea like the big bang that initially was hard to like, let alone understand, another even more mind-bending one comes along. Steinhardt and Turok, cosmologists at Princeton and Cambridge, respectively, present their case that string theory gives a more complete account of our origins; in this account, the big bang came about through the collision of two membrane-thick strings called "branes." Our universe sits on one brane, which floats parallel to the other, unseen one. Every few trillion years, the two branes approach each other; when they collide, a flash of radiation annihilates everything in both, kick-starting the creation process all over again. According to the authors, this solves certain problems with the standard big bang theory, such as inflation, dark matter and dark energy. General readers will be able to follow the authors' clearly laid out, equation-free arguments. Their new theory has little chance of being confirmed experimentally in the foreseeable future, but many who eventually embraced the big bang will doubtless find the notion of cyclic universes and parallel worlds attractive. Illus. (June 5)
Copyright © Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.

From Booklist
*Starred Review* In the big bang, most physicists hear the violent beginning of everything. For theoretical physicists Steinhardt and Turok, however, that bang is but an echo, resounding within a bold new cyclical theory of the cosmos. To be sure, this revolutionary theory (dubbed ekpyrosis) shares much with the standard inflationary version of the big bang. The authors themselves have done much to ratify that generally accepted account of the universe's origins. But their new ekpyrotic paradigm tells a radically unorthodox story about what caused the bang, what happened in the first second after it occurred, and what consequences it will yet produce in the far-distant future. Invoking a sophisticated version of string theory, the authors argue that our universe began not in quantum nothingness but rather in the collision of "braneworlds" sliding together as remnants of an exhausted earlier universe. Moreover, while the regnant theory of the big bang predicts the eventual extinction of the universe, the dynamics of ekpyrosis promise a new beginning, a new cosmos--a trillion years from now. Professional discussion of the authors' daring proposal has scarcely begun. But thanks to this wonderfully lucid book, armchair physicists will understand much of the exciting debate now taking shape at the very frontiers of science. Bryce Christensen

See also the review in Physics World