Mystics at the gate to cosmology

The casual browser might think that The Whole Shebang is a feminist's paean to cosmology. In fact it is a celebration of the big bang theory, as violent a scenario for the beginning of the universe as could be imagined. The initial explosion was a unique event, at least so far as our visible universe is concerned. But what else may be out there? And what was out there, at the beginning, and before the beginning?

Timothy Ferris manages eloquently to combine a conventional description of modern cosmology with a thorough airing of these more metaphysical, and certainly fundamental issues. The basics of the big bang are described in a moderately non-technical and eminently readable prose. Where Ferris excels is with his development of the underlying issues to which professional cosmologists rarely offer more than a token nod, usually as an afterthought. Of course, more questions are raised than are answered as philosophers and theologians, as well as astronomers and physicists, are encouraged to join the fray.

Consider the tantalising topic of multiple universes. The universe may exist in an infinity of incarnations, each one subtly different. Quantum cosmology, in at least one of its variants, asserts this to be the case. But does quantum weirdness have anything to do with reality? I doubt it. Still, the logic is worth examining. The universe is expanding and therefore it had a beginning. Extrapolate known physics towards the beginning, and we reach a point of failure. Classical physics is inadequate to cope with the extremes of density and temperature that we know must have been present. So far, so good. Enter quantum cosmology: here is where the fun begins.

Quantum uncertainty is the essence of what quantum theory has to offer cosmology. The uncertainty principle is well measured on subatomic scales. It explains why particles are sometimes particles and sometimes waves, manifest in such devices as the electron microscope. A wave can weave its way around atoms, through seemingly solid matter, a phenomenon known as quantum tunnelling. Imagine the chair on which you are sitting tunnelling through to the floor below. Quantum theory says that this could happen, though the probability of such an occurrence in your lifetime, or even that of the earth, is infinitesimal. Yet this seeming reluctance of quantum fuzziness to exert itself on macroscopic scales has not deterred cosmologists from postulating that cosmic fuzziness applies on cosmological scales, and is the supreme arbiter of the beginning of time.

Here is how it all began. Eminent relativity theorists John Wheeler (to whom we are indebted for coining the phrase black hole) and Bryce DeWitt were at a loose end on some, one can only speculate, taxing social occasion in the 1960s when Wheeler posed the question: "We demand of physics some understanding of existence itself." Their solution: take the equation for a wave function of an atom, which expresses the atom's fuzziness in position and time, and reformulate it for the entire universe, envisioned as some sort of super-particle. It took only another decade or two before James Hartle and Stephen Hawking solved the Wheeler-Dowitt equation to derive what they boldly asserted to be a prescription for the wave function of the universe. Armed with this, they could predict the present state of the universe, and in so doing evade all of the issues surrounding the moment of creation and the initial singularity. Fuzziness was elevated into a supreme role, which was just as well given the scarcity of alternative hypotheses.

Of course once the quantum Pandora's box was opened, there was no going back. An electron cannot simultaneously be particle and wave. Who chooses? One widely accepted interpretation blames the observer. Until he or she looks, a quantum system has neither state. The Copenhagen interpretation of quantum theory is that the act of observation resolves the system into a particular state. But this hardly helps us with the very early universe, when observers were exceedingly rare, and neither observation nor measurement could have been fundamental elements of the theory. The resolution was not observation, but rather lay in the concept of observability. This may seem a subtle distinction, but the consequences are shattering. Now one has an infinity of possibilities, and an infinity of histories. What subset of this mind-boggling vista of events actually occurred is a question that is answerable, at least in principle, and one that can be posed to astronomers. Of course, whether they can provide any meaningful answers is debatable.

One striking implementation of the concept of multiple universes begins with complete chaos. The origin of the universe is explained, and not assumed, by the postulate that quantum chaos breeds inflating bubbles, within which further bubbles develop and inflate. Any one of these could be our universe, except that our observed universe is remarkably vast compared to the scale of things near the quantum era. So we require an exceptional bubble, but there is an infinite time available to await its spontaneous birth. There is an infinity of universes, all but one of which are forever inaccessible to us. The most probable one is the largest, and by a sort of Darwinian-like survival of the fittest, this is the universe that outgrew its rivals to end up as the most likely candidate for our very own universe.

These multiple universes are not necessarily real. One quantum view asserts that reality requires an observer. Another, the many-worlds hypothesis of Hugh Everett, requires parallel universes to be more than magnificent hypotheses: they occurred and exist, at least until the observer points the telescope, when just our own boring patch of space-time is seen. And then there is the almost mystical concept of hidden variables, due to David Bohm, that act as the observer's ghostly all-pervading hands which instantaneously pluck the measured state from the myriad of alternative forms. Here, if not before, is where metaphysics and science begin to overlap. Once the scientists dabble in mysticism, there is no stopping the philosophers, theologians, and the cohorts of amateurs, with their own pet theories, who are clamouring to breach the gate to cosmology.

All of these attempts at quantum cosmology may be premature. They avoid the toughest of questions: what is matter? To understand the origin of the universe, we must first refine our understanding of the ultimate nature of matter. This involves unifying gravity with the three other fundamental forces, since there is essentially no doubt that gravity, now the weakest force by far, was once on an equal footing with electromagnetism and nuclear interactions during the regime of the immense densities and pressures achieved at the beginning of the cosmos. String theory has provided indications of a possible clue to such a unifying theory.

Superstrings are ten-dimensional objects that are subatomic particles, but only recognisable as such once the six extraneous dimensions have collapsed in a phase transition that occurred some 10-43 seconds after the big bang. Superstrings give an elegant geometric interpretation of elementary particles, and yield a theory whose mathematical beauty is so compelling that an army of physicists has locked step to the drum-beat of such pioneers as Ed Witten. Yet the mathematics is complicated. It requires at the last count some 496 different and unspecified counterparts to the photon, which alone suffices for electromagnetism as a force carrier. Little wonder that critics such as Sheldon Glashow have written: "Contemplation of superstrings may evolve into an activity... to be conducted at schools of divinity by future equivalents of medieval theologians." Witten rather feebly counters by arguing that "good wrong ideas that even remotely rival the majesty of string theory have never been seen". Cosmology is in dire need of inspiration. It has provided a theory of the universe that lacks a beginning. String theory may provide the answer, but its sheer complexity inevitably reminds one of Leon Lederman's dictum: "If the basic idea is too complicated to fit on a T-shirt, it's probably wrong."

Cosmology also has much to say about the possible fate of the universe, although the big bang theory lacks a definite ending. Astronomers disagree on predictions for the future of the universe, as to whether it will continue to expand into an ever colder and blacker vastness, or whether its expansion will decelerate and reverse, culminating in a final flash of glory that mimics its singular origin. Some believe that observational data may already contain the information necessary for such an extrapolation. A= more general consensus holds that, even if current data is incomplete, the ultimate questions about our cosmic fate will be answerable within a decade or two as improved observations become available.

Observational aspects of cosmology constitute one area where Ferris's book could have benefited from more professional oversight. Explanations of distance techniques such as the Sunyaev-Zeldovich effect and the surface brightness fluctuation technique are slightly garbled. But this is a minor quibble. Highlights of the book include the many quotes that Ferris has extracted over decades of attendance at seminars and conferences, presumably with his tape recorder in action, and from personal interviews with some of the leading cosmologists. These comments, often sharp yet unpolished, provide unique glimpses into the thoughts and ideas of the people that have helped define modern cosmology. Individuals come alive as one reads about their backgrounds and inspirations. The Whole Shebang is written by a former journalist and aimed both at, and beyond, the world of scientists. It is a grand success.

Joseph Silk is professor of astronomy and physics, University of California, Berkeley.