The original version of a review that appeared in the Wall Street Journal, 7 June 2014, edited for their house style.
The Island of Knowledge
In the words of the Lovin’ Spoonful song She is Still a Mystery, written by John B Sebastian, “the more I see, the more I see there is to see.” This should be Marcelo Gleiser’s theme tune, since, as a refreshing antidote to those pessimists who argue that the end of physics is in sight, he claims that there are no limits to science and that there will always be unknowable things. “The more we know,” he says, “the more exposed we are to our ignorance, and the more we know to ask.” This is a liberating insight, which makes science an open-ended pursuit, a “romance with the unknown”.
This is brought home by the allegory implicit in the title of his book. What we know, according to Gleiser, is like an island in a sea of the unknown. As we learn more, the island grows; but as the island grows its circumference, the boundary between what is known and what is unknown, also grows. The more we see, indeed, the more we see there is to see. If the sea is infinite, this process will continue forever; and the message we take away from the book is that the sea is indeed infinite.
All this is set in the context of a relatively conventional but very accessibly presented resume of the development of science (in particular, physics) from ancient times to the present day. The story is presented in three parts. First, what might loosely be called cosmology, the study of the Universe at large. This is good. Secondly, we have the story of the very small, essentially the story of quantum physics. This is excellent. Finally, we have some speculations about mind and matter. This is the weakest part of the book, but only in comparison with the quality of the earlier sections.
One of the key features of the story he tells is a point that I often emphasise when discussing how science works with non-scientists. It is a common misconception that scientists are interested, above all, in getting confirmation of the predictions of their existing theories — in physics the so-called “standard model”, which among other things predicted the existence of the Higgs particle. Physicists were, of course, quite pleased that the particle was indeed found. But they (even Peter Higgs himself!) would have been a lot more pleased if the theory had been found to be incomplete, and there was no sign of the predicted particle. That would have given them the opportunity to learn new things — to expand the island of knowledge. For example, Newton’s theory of gravity failed to explain details of the orbit of Mercury around the Sun, pointing the way towards Einstein’s general theory of relativity. Newton’s theory still works within its limitations, but there is more to gravity than Newton knew. Perhaps there is more to gravity than Einstein knew.
Gleiser’s assessment of the future of science is distinctly different from that of many — perhaps a majority — of scientists and commentators. Back in 1996, John Horgan made a splash with his book proclaiming “The End of Science”. His argument was that the foundations of science, such as the Big Bang theory, the structure of DNA and evolution by natural selection, were well established and not going to be changed, except in detail, by new discoveries. Deliciously, just a couple of years later astronomers were surprised to discover that the expansion of the Universe is accelerating, that, two-thirds of the Universe is composed of mysterious “dark energy”, that the stuff we are made of (atoms) makes up only 5 per cent of the Universe, and the Big Bang theory is not as complete as we thought. But that has not stopped people repeating essentially the same argument as Horgan in the present century.
For example, in 2009, the science journal Nature hosted a debate on the future of science (http://blogs.nature.com/nautilus/2009/06/the_nature_big_science_debate.html), where Lewis Wolpert, of University College, argued that fundamental biology is essentially complete and unlikely to spring any major surprises. Although important things remain to be discovered (such as details of the process of the development of an adult organism from a single cell), the “fundamental architecture” is not going to change. I would guess that Gleiser’s counter-argument would involve the puzzle of the interplay between mind and matter discussed towards the end of his book. Until we know what consciousness is, how can we claim to understand biology?
At the same meeting, Alison Wright, editor of the journal Nature Physics, took a marginally less extreme position, admitting that although physics is in a very satisfactory state, it is a subject in which the adage “never say never” applies with full force to the prospects for a revolutionary change. She was no doubt aware of the comment often attributed to William Thomson (Lord Kelvin), who is reported as saying in 1900 that “there is nothing new to be discovered in physics now. All that remains is more and more precise measurement”. There is some doubt about the attribution, but no doubt that just after this was allegedly said at a meeting of the British Association for the Advancement of Science physics was shaken by not one but two revolutionary developments — quantum physics and relativity theory.
Perhaps with this in mind, and referring to the present Holy Grail quest for a “Theory of Everything”, Gleiser sums up:
“Notions of final theories are incompatible with the scientific method. Given that we can only accrue scientific knowledge from measurements of natural processes, it is by definition impossible to be certain that we know all the forces of Nature or the fundamental particles that exist; at any point in time, new technological tools may reveal the new and unexpected and thus force a revision of our current knowledge.”
There may be such a revision (or revolution) in progress at present. Astronomers of today will tell you, with great confidence, that the Universe as we know it was born 13.82 billion years ago; the natural question to ask then is, “what happened before that?” Until recently, that was regarded as either unanswerable or meaningless. There was no “before”, we were told. Time itself began at the moment the Universe was born. When I was a student I was told that it was meaningless to ask what happened before the time when the entire Universe had the density of an atomic nucleus — the time of the Big Bang. But now cosmologists also talk confidently about the inflation that preceded the Big Bang, earlier than one ten-thousandth of a second after the birth of the Universe from something like a singularity, a point in spacetime. This involves the process known as inflation, which took a a tiny seed — a “quantum fluctuation” and blew it up to become the Big Bang. Inflation theory has recently received a great boost from the apparent discovery of gravitational ripples produced in this process (although I should caution that these results have not yet been independently confirmed). And inflation theory does tell us what happened “before the beginning”.
According to the equations, this inflating spacetime would be just one bubble in an infinitely large and eternal metaverse, with no beginning and no end. Within this metaverse, the story goes, there are regions which form inflating bubbles. Our Universe is such a bubble, and the implication is that there are other universes, other bubbles far away across the inflating sea, like the bubbles that form in the liquid when a bottle of champagne is opened. This seemingly speculative idea counts as a genuine scientific hypothesis, because it makes testable predictions. If other “bubble universes” exist in the metaverse, it is possible that long ago one or more of them may have collided with our Universe, like two soap bubbles touching and moving apart. One effect of such a collision, Gleiser points out, would be to make ripples in the space of both bubble universes that would leave a distinctive, but faint, ring-shaped pattern, known as a “cosmic wake” in the background radiation that fills the Universe. The Planck satellite is testing this prediction right now. Is the metaverse real? “We should know,” says Gleiser, “by mid-2015”.
One way or the other, this will not bring an end to the cosmological quest, which itself is just one aspect of the scientific quest. This is, to my mind, an upbeat conclusion. The quest goes on, always presenting us with new things to wonder about, and to wonder at. Without that sense of wonder, as this excellent book makes clear, there would be no point in doing science at all.
John Gribbin is a Visiting Fellow in Astronomy at the University of Sussex
and author of In Search of the Multiverse.