Why Does the World Exist?, By Jim Holt

A fine study of the laws of the universe interrogates what, if anything, came before the Big Bang

Why is there something rather than nothing?" is a question I have tormented myself with for exceedingly brief periods of my life. When I do, I always feel a bottomless pit opening up and step off this journey pretty sharpish. But Jim Holt, a New Yorker essayist and philosopher, dusts the question down from every conceivable angle, gets out and about interviewing great thinkers and succeeds in showing us that, answer or none, there's nothing to be afraid of in contemplating it.

There are only three kinds of possible solution to this problem: religious, philosophical, or scientific. And most attempts run into one of three dead-ends: circularity, infinite regress, or brute fact. The puzzle that the universe seems to obey mathematical laws has suggested to some that in the beginning was mathematics (which would still exist Platonically even if there were no universe) which then engendered physical reality out of necessity, but this is clearly circular. The quest for a scientific explanation is vulnerable to infinite regress: there always seems to be another, more fundamental particle waiting to be discovered; and if there was a Big Bang, a singularity, what came before that? Brute fact is most people's get-out-of-metaphysical agony card: there is a universe; always has been – get over it.

I had expected much discussion of the Goldilocks Principle, the strange way that several physical constants happen to be just the right size to allow matter to form in the first place; for the 92 natural chemical elements to arise; for carbon to form endless complex molecules; for self-replication to occur; and finally, but not least, for water to freeze at just the right temperature to prevent life in the oceans being destroyed by ice. But the concept only gets passing mentions. One interpretation of this conundrum, however, the multiverse, is extensively treated. David Deutsch is the magus of the multiverse. He and some others conclude that the reasons that our world is so finely tuned to life are: 1) if it weren't we wouldn't be here; 2) there are a myriad other universes with different physical constants; ours is the lucky draw that was able to flourish in the way we know. Who knows what the others might be like?

Even if our universe had that Goldilocks potential, it still had to start somehow. The favourite explanation is chaotic inflation. According to this, if you could empty the universe of all matter it would not be empty: a perfect vacuum is still seething with quantum energy and from this can come forth matter.

Only a tiny smidgeon of primary stuff formed in this way would then inflate dramatically and chaotically, as the post-Big Bang universe is fairly reliably thought to have done. Mathematically, the creation of all this apparently solid stuff from nothing isn't a great sweat, however bizarre the idea seems to most of us, especially those who were taught at school the principles of the conservation of mass and energy. What is special about Why Does the World Exist? is that Holt and the experts he talks to apply humour, good sense, and a dose of incredulity and wonder to the problem.

But they also go quite deeply into the philosophy. No one more so than John Updike, who kept up with science and in his novel Roger's Version (1986) tackled this very question. Intellectually, Updike could consider the theory of chaotic inflation but, in the end, "my reptile brain won't let me . . . it's impossible to imagine that even the earth was once compressed to the size of a pea, let alone the whole universe".

Nevertheless, Holt is very good at explaining that the physical weight of the world that worried Updike is something of an illusion. Most of the massy stuff around us is empty space and its apparent solidity a consequence of two prime laws of quantum mechanics: Pauli's Exclusion Principle and Heisenberg's Uncertainty Principle. As the Roman poet Lucretius knew 2000 years ago, properties at the most infinitesimal dimensions do not carry through to the macro world that we inhabit.

Besides Updike and Deutsch, the sages Holt consults include Roger Penrose, Steven Weinberg and Robert Nozick. Holt's accounts of these encounters are disarmingly modest and replete with details of the great man's lair. The last, charming, word should go to John Updike: "The whole idea of inflationary expansion seems sort of put forward on a smile and a shoeshine".

Peter Forbes's 'Dazzled and Deceived' is published by Yale University Press