Paul Davies

THE GOLDILOCKS ENIGMA

Why is the universe just right for life?

Davies has written about the origins of the universe before, notably in The Mind of God. I found that book rather disappointing, containing as it did a good deal of, to me, rather unconvincing theological discussion, but this one is a great deal better. It provides an excellent overview of modern thinking about how the universe may have arisen and of the philosophical issues that arise therefrom. Davies is a very experienced popularizer of science and he writes exceptionally clearly. A useful feature of the book is that each chapter ends with a summary of its key points, which makes it easy to refresh one's memory about what has gone before.

The first chapter outlines the main issues to be discussed, notably the view (widespread but not universal among scientists) that the universe is pointless. "Somehow I am supposed to explain all this," Davies concludes rather disarmingly.

Next comes a chapter looking at the presumed origin of the universe in a hot big bang and setting forth what we know about its present state. This theme is taken further in Chapter 3, where we look at the currently very popular theory of inflation as an explanatory mechanism for its structure. The multiverse idea (the possible existence of very many universes) is also introduced here.

Chapter 4 probably requires the most concentration from the reader, because it presents a summary of atomic physics—the kinds of particles that exist and how they are related to one another. We also meet the four fundamental forces (electromagnetism, the strong and weak forces, and gravity) and the attempts that have been made to tie them all together. This includes a short discussion of string theory and what it may tell us about the fundamentals of physics if it ever becomes fully established..

Chapter 6 is about the mysterious dark matter and even more mysterious dark energy that figure in modern astronomy. Whatever they are, they constitute 96 per cent of the universe. The ultimate fate of the universe is thought to depend on exactly how dark energy will act in the future.

In Chapter 7 Davies begins to tackle the question of why the universe is apparently so finely adjusted for life—the Goldilocks enigma of the title. This has been termed "the big fix". If certain physical constants were only very slightly different from what they actually are, the universe would have been totally unsuitable to support any form of life that we can conceive of or might have been still-born. But at present it seems that their values are not fixed by anything, and some theists take this to be evidence for intelligent design.

One popular way of avoiding that conclusion is to postulate the existence of multiple universes (the multiverse). If there is a huge number of universes, perhaps some possess, by chance or for other reasons, the right conditions for life, and obviously we would not find ourselves in one that lacked these. But there are difficulties with the multiverse idea, which Davies discusses in Chapter 8. One of these is the possibility that the multiverse might contain simulated as well as real universes, and we might be living in one of those. He discusses the simulation hypothesis in some detail. Although it is impossible to disprove, it is best ignored because there would be no point in doing science if it were the case.

Chapter 9 is more theological than the rest and looks at the argument for intelligent design. A creator god need not necessarily be omnipotent, and could indeed be simply a very advanced being that had evolved in another universe (a Platonic demiurge). But saying that the universe was created by God is, as Davies puts it, "a conversation-stopper". It doesn't really explain anything and raises philosophical problems about a "necessary being". Moreover, such a being need not have any of the other attributes of the Christian God. The demiurge idea seems to me to be the theological equivalent to the simulation hypothesis.

In Chapter 10 we meet the type of theory that Davies himself is most attracted to. Theories of this kind are teleological, which means that they see a trend towards the production of life as built into the universe. Teleology is very unfashionable in science today, largely because it seems to offer a toehold for religion, but Davies says that it could be accommodated within science if we accept the possibility of backward causation in time. This certainly sounds very odd but apparently it is scientifically "quasi-respectable". It would allow observers today or in the future to help shape the nature of reality in the past. This might be a self-explaining universe (or possibly multiverse), with no need to postulate anything else to account for it. Although Davies does not use the term, one could call this a pantheistic account of creation.

If you find these last ideas difficult to come to terms with, you are not alone; it seems that Davies does too. He concludes his book as follows:

The whole paraphernalia of gods and laws, of space, time and matter, of purpose and design, rationality and absurdity, meaning and mystery, may yet be swept away and replaced by revelations as yet undreamt of.

In the meantime, Davies's book provides one of the best accounts of the present state of affairs in cosmology that I have seen. I particularly like his Afterword, in which he conveniently summarizes the case for and against each of the theoretical positions that are currently on offer.

12 November 2006