Jim Holt

WHY DOES THE WORLD EXIST?

An Existential Detective Story

But if you are one of those who do find themselves pondering the question, at least occasionally, this book is for you. Holt is a writer and philosopher who has thought about it for much of his life. Here he gives us the result of his attempts to find a solution. His method is to use interviews with well-known thinkers, which are interspersed with 'interludes' in which he reflects on what he has heard and makes suggestions of his own. There are also more personal touches occasioned by his surroundings (often in Paris) and sometimes events such as the death of his beloved dog. There is a good deal about food and drink, both of which Holt evidently enjoys.

In the past, the question of why anything exists was pretty much left to the philosophers and theologians, but now it seems to have moved beyond speculation and become open to scientific investigation. This is quite a new development. Until comparatively recently the dominant idea among astronomers and physicists, including Einstein, was that the universe has always existed. But in the twentieth century came the discovery that the universe is expanding, which prompted the logical inference that it must have had a beginning. Today the orthodox view is that it started with a Big Bang. But what happened before the Big Bang (assuming that this question makes sense)? There are theories that propose the universe might have winked into existence as a kind of quantum fluctuation, but even if that is true, it does not explain why there was not simply nothing at all, including no laws of physics. So is science the right place to look for an answer?

Some people definitely think it is. In 2006 Holt received an unexpected letter from Adolf Grünbaum, an eminent philosopher of science, who said simply "There is no mystery of existence." Holt visited Grünbaum, whom he calls the Great Rejectionist. Their conversation altered his thinking in some ways but did not shake his conviction that the problem of existence is a real one.

His next interview was with someone at the other end of the philosophical spectrum, the Oxford theologian Richard Swinburne, for whom the fact of existence leads logically to the idea of God. Swinburne's thoughts were subtle and sophisticated, and the interview produced a good few surprises for Holt, including the discovery that Swinburne's Christianity is Eastern Orthodox.

Scientists who reject the idea of God are faced with the difficulty of explaining why many of the physical constants in our universe are apparently arbitrary yet are finely tuned to allow the existence of life. A popular way of accounting for this is to postulate the existence of many universes. If there are huge numbers or even an infinity of universes, there will by chance be some in which life is possible, and of course we would not be there in a universe that was inhospitable to life. There are actually two versions of this idea: one derived from cosmology, the other from quantum mechanics (Everett's 'many worlds' theory, according to which the world is continually splitting up into innumerable alternative versions).

The most prominent advocate of the second version is the physicist David Deutsch, whom Holt visited in Oxford after Swinburne. (Deutsch is probably the greatest expert in the world on quantum computing, which makes it rather startling to read that when he graduated from Cambridge he barely scraped a 'pass' degree in mathematics!) The laws of quantum physics can't tell us why anything exists, Holt learnt, but there is still the possibility that reality may explain its own existence.

Back in the USA, Holt next interviewed the physicist Steven Weinberg. The encounter deepened Holt's understanding of how science works, but Weinberg did not think that science could explain the mystery of existence. If a solution could be found it would not be through science.

Returning to Oxford again, Holt visited the mathematician and physicist, Roger Penrose, whom he describes as a Platonist. That is, Penrose holds that there are three worlds: the Platonic timeless world, where mathematics resides, the physical world, and the mental world. All three depend on one another and interact in a mysterious way, but the Platonic world is primary and gives rise to the others. But, Holt wondered, is its existence guaranteed by logic, as Penrose holds? And even if it is, how does it give rise to the other two worlds?

There is another British Platonist, John Leslie, who now lives in Canada, where Holt visited him, to hear him propound a rather difficult-to-understand view that the world exists thanks to an abstract principle of goodness. Holt did not find this entirely convincing, but perhaps, he thought, there might be some other abstract principle that could account for the world.

Holt's penultimate interview was with yet another Oxford philosopher, Derek Parfit, who had already written about the question that obsessed Holt. While staying for a couple days, rather improbably, at the Athenaeum Club, where there was a clock with two '7' figures but no '8', Holt did a lot of intensive homework before the interview. This took the form of Holt's asking Parfit for confirmation of the ideas he had understood from his reading. Parfit's views seem to have been the most fruitful that Holt encountered.

On his return to New York, Holt experienced an illumination in which he formulated a theory of existence based on Parfit's work. He prints the letter describing this theory, which he sent to Parfit. Parfit replied, "Thanks for this message, which is very interesting. I shall have to think about it carefully." It's not clear whether this was a polite brush-off or an expression of genuine interest. Anyway, it is not the end of the book.

The final interview was with John Updike. He mentioned shortness of breath on exercise, which he attributed to age, but in fact a year later he died of lung cancer. In spite of his interest in science, Updike professed himself unable to take on the views of cosmologists at the intuitive level.

The concluding chapters are more personal. Holt movingly describes his reaction to his mother's death, and he tells us a little about his own background, including his Catholic upbringing, which he later rejected. This is an unusual way of providing such biographical material—many writers would place it at the beginning. But this is a very carefully constructed book, and Holt is selective in what he tells us about himself. I would have welcomed more.

29 March 2013