Universe expands as inflation soars

The Inflationary Universe - The Life of the Cosmos - Hunting down the Universe
August 15, 1997

The popular science books that sell best are those that promise to tell us not about the science behind computing, biotechnology or electronic engineering, but about fundamental matters such as evolution, the working of the brain or the origin and structure of the universe, as a feature article in The THES recently pointed out (Gail Vines, July 25).

The problem with the last of these subjects, cosmology, is that for a long time it lacked the data available to other branches of science. But now cosmologists know how big the universe is and how old, how much matter it contains and how much energy, and how its structure is organised on small and large scales. We even know which of its atoms were created at what stage, some in the big bang and others within stars, later on. Indeed we know so much that it is possible to speak with some certainty about how the universe got to exist, what our place is within it, and even whether we are in "the" universe or one of many universes.

Two of these three cosmology books are written by "star" cosmologists, Alan Guth and Lee Smolin. The third author, Michael Hawkins, an astronomer at the Royal Observatory, Edinburgh, though not such a leading figure, is a significant player in the developments that all three books describe from different angles.

If your holiday suitcase has room for only one of the three, go for Guth, for his attention-grabbing clarity. Guth is the man who in 1980 proposed the theory of "inflation", which one has to grasp in order to understand the latest cosmological thinking, and he explains it best of the three authors.

Inflation is the term used for a stage in the very early universe in which it expanded exponentially many billions of times in less than second. This was possible because the pre-inflationary universe existed as a peculiar, transient form of matter called a "false vacuum" - false, because it was metastable with a higher energy density than the true vacuum that the universe became after inflation.

High-flown as this idea may sound, it came from considering a highly specific scientific problem. Electrons and protons carry a single charge, either negative or positive -but magnets are never observed with an isolated north or south pole, they are always bipolar. And yet, according to the so-called grand unified theories (GUTs) of cosmology, such magnetic monopoles must have been produced in the very early universe. At one point in their work Guth and coworkers calculated that monopoles should have been 10,000 times more common than protons and neutrons; at another point, their model produced such a huge supply of monopoles that the universe would have collapsed before it was 1,200 years old. The concept of inflation was introduced by Guth to avoid such absurdities.

Inflation is a neat enough idea as it is. It allows Guth to predict that the universe will be close to being "flat", containing just enough matter to teeter on the edge of expanding forever or collapsing, once its present expansion ceases. But Guth goes further, combining inflation with a sudden "phase change" at the end of the expansion. This permits many gross features of the universe including the existence of large-scale structure to be accounted for.

In Guth's view, the false vacuum can collapse to yield not one universe but many. Our universe is very unlikely to be the first or the last. Like all the others, it sprang from a tiny false vacuum less than an atom in size, and there are, have been and will be many others.

Guth knows his history of science, and would probably agree that this multiple universe idea is a further step in the progress of our self-knowledge. A few hundred years ago, people in the European cultural tradition thought that a small universe of recent age had been created in a week by a God whose duties also included miracles and the forgiveness of sin. Since then, the fact that the universe is big and old, that we are related to other creatures and that our planet seems special only to us, have demolished our position of particularity. Nevertheless, the idea that even universes are not unique and that the origin of everything is literally nothing, is still a lot for us to swallow. In fact the idea is not yet 25 years old: it was in 1973, says Guth, that Edward Tyron asked whether the universe is a vacuum fluctuation.

Now there are more than 200 scientific papers a year on inflation, although even Guth is careful to say that the idea is "accepted but not proven". Guiding the lay reader through this complexity would be a demanding task for a professional writer, but it is a godsend that the writer who was at the centre of such developments can also describe them as well as any professional writer.

The Inflationary Universe is the book of the year for anyone interested in the biggest of big ideas, but Lee Smolin's approach to a similar field in The Life of the Cosmos comes a close second. Like Guth, Smolin can write, and both books are surprisingly likely to make you laugh. Smolin is modest about his own very significant achievements, but leaves no doubt that his scientific career has been no accident. Before entering college, at a time when his examination results did not suggest he was a major figure in fundamental research in the making, he wrote out these three questions. 1. What is the Universe? 2. Within the context of the answer to the first question, what is a living thing? What is life? 3. Within the context of the answers to the first two questions, what is a human being? Who are we?

We have now reached the point when it has become possible to say something sensible about all of these questions.

For Smolin, even such apparently abstract activities as astronomy are secondary sciences, mere appendages of the genuine truth-generating topic of fundamental physics. But the work he does connects directly to observational science. At one point, almost as an aside, he explains just why gravity wave and neutrino astronomy, two of the most obscure branches of the subject, both devoted to obtaining "ground truth" on fundamental theories of the universe, are worthwhile.

Guth's universe is one of many, and has come to exist via a process that can produce many others we can never observe. For Smolin, the mystery is that the universe we have works in anything like the way it does. For example, stars. These are useful as well as decorative, being responsible for making most of the heavy atoms in the universe. But if the force of gravitation were a little stronger or weaker than it is, stars would last only a few thousand years and the universe would be a completely different place. Or take the mass of the neutron and the electron. If they were slightly different, there could be no stable atomic nuclei, and therefore no atoms. Or take another fundamental number, the so-called cosmological constant. If it were slightly bigger than the tiny number we observe, the universe could be as small as an atom and last only a few seconds instead of billions of years.

For Smolin, the basic numbers that underlie the universe around us, and allow us to exist, are so bizarre that they cannot simply be taken for granted, as if God had just set a row of dials at random on the day of creation and let the results work themselves through.

This is even true of inflation itself, where the parameters must have been tuned with immense precision for the universe we see to have been possible. It is as if the Bank of England (or the Federal Reserve, in Smolin's example) had been altering interest rates by a millionth of a per cent to avoid financial inflation over a billion years. And quantum physics, from which these numbers emerge, is so accurate that measuring the gross national product of the United States to the nearest cent would be sloppy work by comparison.

The key to this set of oddities, Smolin thinks, is that all those stars have another important end-product. The big ones blow up and when they collapse back, the result is a black hole. Each of these is a new region of space and time - another universe, possibly complete with its own black holes and its own laws of physics.

This is, in effect, Guth's conclusion, arrived at by a new route. But there is a satisfying twist. The universe of stars and black holes that we inhabit is one that generates lots of stars and lots of black holes. This means that it has probably been generated by another universe of similar properties, since black holes are the input to the creation of new universes.

Of course, the starry, long-lived universe that we see around us is also a friendly home for life in general and our own species in particular. For Smolin, life is a planet-sized layer in a hierarchy of organisation running in scale at least up to the size of the galaxy and possibly beyond. It has self-organisation much as a galaxy does and is dependent upon the "non-equilibrium" conditions of the universe around it, including the existence of clumps of matter making up the planet and other larger ones making up stars to pump out energy.

Smolin's view is of a piece with the Gaia theory of life on Earth and with work on nonlinear theory (so-called "chaos") and self-organisation. His views do not need a God, but they do involve respect for life and the world it inhabits. His book is convincing if also heavily over-written.

By contrast with these theoreticians, Michael Hawkins is a real astronomer who uses telescopes and observes the universe for a living. By the end of his dust jacket you already know about his father (a rear admiral), his time as a submariner, his horse and his air crash.

His book is likely to remain a likeable curiosity, as ill-focused as the jacket photo of the author. In the main this is because of its catastrophic disorganisation. At the start, we are told he has made a huge discovery. But page 100 has come and gone before we find out what it is: the possible physical nature of the "dark matter" that accounts for much of the mass of the universe. According to Hawkins, tiny black holes dating back to the origin of the universe may account for much of this material.

But the author's real aim in writing Hunting Down the Universe seems to be to rehabilitate Fred Hoyle's unfashionable belief in the incorrectness of the big-bang theory of the origin of the universe and even more to rail against the scientific establishment and the money it lavished on the Hubble Space Telescope. Oddly enough Malcolm Longair, one of the leading Hubble scientists and Hawkins's former boss as head of the Royal Observatory in Edinburgh, does not feature in the book, while his predecessor, Vincent Reddish, does.

For Hawkins, Hubble is a bad idea and the scientists who use it are suffering from mass delusion. He even finds Hubble images ugly, preferring the clarity of those produced by the Earthbound Schmidt camera.

There ought to be room in science for someone who attacks received wisdom, but Hawkins seems to have set himself too large a task. It is trite to point out that computer simulations only work from the assumptions we put into them, and wrong to say that "tame journalists" are supporting Hubble. Indeed, the Hubble community is still smarting from their journalistic mauling over some minor engineering problems when the satellite was launched. And when reporters got wind of Hawkins's discovery, he admits to being impressed by the astuteness of their questions and the accuracy of their reporting - even in The Sun.

It is a pity that the publishers allowed the book to appear in a state where a good deal more work was needed. And it is amusing to see that they have included a gorgeous picture section entirely drawn from the hated Hubble, precluding the reader from forming his own view about the Schmidt imagery admired by the author.

Martin Ince is deputy editor, The THES.

The Inflationary Universe: The Quest for a New Theory of Cosmic Origins

Author - Alan H. Guth
ISBN - 0 224 04448 6
Publisher - Cape
Price - £18.99
Pages - 358

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