[Slightly abridged versions of this article appeared under the name "A New Fabric of Reality?" in The Times Higher Educational Supplement (5 June 1998) and in The Weekend Australian]
Science in the modern sense began with Galileo's conception of a law of nature: a universal statement about reality, expressed in unambiguous symbols and tested by what he aptly called 'ordeals' (we would call them crucial experiments). Ever since then, a recurrent theme in the history of science has been the tension between two great purposes that are implicit in Galileo's conception: science as a means of making predictions and giving us control of the world; and science as a means of understanding what the world is really like.
No one claims that prediction and understanding are incompatible purposes. Yet they sometimes pull in different directions, and questions of how they are related -- whether, for instance, one of them is subordinate to the other -- have been the subject of bitter controversy. This is not just a storm in an academic teacup. Nor is it even just a matter of whether science is defensible as a mode of thought and a basis for action. Scientific progress itself has always depended on answering such 'metaphysical' questions correctly.
Galileo's own confrontation with the Inquisition was a case in point. Following his brilliant advocacy of Copernicus' theory that the Earth moves round the sun, Galileo was convicted in 1633 of heresy, sentenced to house arrest for life, and forced, under the threat of torture, to declare that he "abjured, cursed and detested" the Copernican theory. As Jacob Bronowski put it in The Ascent of Man: "The result was silence among Catholic scientists everywhere from then on ... The effect of the trial and of the imprisonment was to put a total stop to the scientific tradition in the Mediterranean." But it is important to understand what Galileo was not forced to recant. The Inquisition did not object to his claim that Copernicus' theory provided a useful, pragmatic model of the solar system and gave accurate predictions. Predictions, you see, refer only to observations and are therefore merely a matter of appearances, while what the Church cared about was reality. They were happy to cede utility and observational accuracy to the domain of science, so long as science was prepared to leave objective reality to them. And that is exactly what Galileo had not been prepared to do. He knew that if his symbols were understood as referring only to appearances and not to objective reality then they, and the whole edifice of scientific reasoning, made no sense.
By a strange (and, I would add, scandalous) quirk of intellectual history, many of the most influential philosophers and scientists of this century have in effect sided with the Inquisition in this matter, and against Galileo. Going variously under such names as 'instrumentalism', 'logical positivism' and 'I'm just a simple scientist, I don't hold with metaphysics', the doctrine has been that the entire content of a scientific theory lies in its observable predictions. Explanations of why the predicted events come about, if couched in terms of entities that cannot be directly observed (such as quarks, curved spacetime or parallel universes) are regarded as matters of taste: optional extras, not really part of science at all. Any consistent explanation that a theory may give for its predictions is deemed to be as good as any other, or as good as no explanation at all, so long as the predictions are borne out by experiment.
So was Galileo arguing about nothing, when he insisted that the Earth really is moving and does not just appear so to astronomers? Of course not. Certainly, performing crucial experimental tests is the defining method of science: we seek only testable theories and we reject every theory that fails an experimental test. But to think that surviving experimental tests is the purpose of our theories is like thinking that the purpose of an aeroplane is to pass airworthiness tests. Worse, actually, because one can fly an aeroplane into new territory without altering its design or knowing how it works. But in science, progress means better explanation, and all the other functions, methods and uses of science are dependent on explanation. Take medicine for example, one of the most pragmatic of the sciences. We may be able to recognise a disease without understanding its origin. We may be able to predict its symptoms and give a prognosis. If we are extraordinarily lucky, we may even be able to cure it with a medicine of unknown mechanism. But to make any further progress -- say, to cure an apparently similar disease that the medicine is ineffective against; or to help the minority of patients whom the medicine makes worse not better; or to find a way of wiping the disease out altogether -- only explanations will do. Predictions by themselves are useless.
| The organisers of the Rhone-Poulenc prize are very pleased that the number of entries this year exceeded those for the Booker and Whitbread prizes, "reflecting the continued growth of the public's interest in popular science books". The strength of this interest, which surprises many scientists, has confirmed my belief in people's desire to understand reality and their place in it. However, it has to be admitted that this is just one among several conflicting trends. It goes along with the increasing alienation of young people from science, and the increasing popularity of every kind of pseudo-science and anti-science, as well as what has perhaps become the most dangerous of these trends, namely scientism (the specious use of scientific authority). But I think that all these trends have the same origin: the innate human sense of wonder, and the desire for things to make sense. I hope that readers of the shortlisted books will find that science has what they want -- not only in the sense of Winston Churchill's austere reflection that "facts are better than dreams", but quite literally: science has led us to facts beyond our wildest dreams, and ideas that make sense at levels that were literally unthinkable before. While real science can help us to make sense of the world, uncritical thinking does not even make for good fiction: if you want good fiction, read a novel; if you want the truth about nature, you need scientific explanations. |
And the same argument is still made today, against the most important implication of quantum theory: that the universe we see around us is only a small facet of physical reality; and that the whole of reality -- the multiverse -- contains many such universes affecting each other through the phenomenon of quantum interference. "Why should we believe that those other universes exist?" some people argue. "Why can't we just say that the universe we observe behaves as if they were out there, affecting it?"
I wish I could pretend that those people were themselves not out there; or at least, that they did not really believe such nonsense, but were merely behaving as if they did. I wish it were unnecessary to explain that taking that view of quantum mechanics -- the fundamental theory that underlies the whole of physics -- impedes further progress and makes it well-nigh impossible to understand that theory or its astonishing connections with other fields of knowledge.
But it is necessary, because this time, it was not only the die-hard opponents of the new theory who retreated into instrumentalism, it was the founders themselves -- many of them, anyway -- and in most branches of physics ever since, the prevailing attitude towards quantum mechanics has been pragmatic acceptance, combined with every sort of refusal to take it seriously as a description of reality. Moreover, this sad state of affairs has been repeated, with variations, in three other fields where important new explanations have been discovered, namely the theory of evolution (as updated by Richard Dawkins); Karl Popper's theory of the growth of knowledge in science; and Alan Turing's theory of the universal computer.
In The Fabric of Reality all four of these stands -- our four deepest explanations of reality -- are taken seriously, not just in their own right, but jointly. For it turns out that they are so closely interrelated that none of them can be properly understood without reference to the other three. Recent research on quantum computers -- machines that perform computations of unprecedented complexity by sharing sub-tasks among vast number of universes -- provides one example of this. Another is the restoration of life and human thought to significance in the scheme of things; for while they seem insignificant in any one universe, from the multiverse perspective they would be recognisable in the very largest structures. Considered together, these four strands of explanation reveal a unified fabric of reality that is objective and comprehensible and in which human actions and ideas play essential roles. This is a rational world view that ought to be the prevailing one -- not the final 'theory of everything', but the starting point for the discovery of even better explanations, and the tentative standard against which all new theories should be judged.