by Peter Watson
The Internet has its critics, such as Brian Winston, who in his 1998 history of media technology warns that ‘the Internet represents the final disastrous application of the concept of commodification of information in the second half of the twentieth century.’13 But few now doubt that the Internet is a new way of communicating, or that soon a new psychology will emerge from relationships forged in ‘cyberspace.’14
In years to come, 1988 may be revealed as a turning point so far as science is concerned. Not only did the Internet and the Human Genome Organisation get under way, bringing about the ultramodern world and setting the shape of the twenty-first century, but a book appeared that had the most commercially successful publishing history of any work of science ever printed. It set the seal on the popular acceptance of science but, as we shall see in the epilogue, in some ways marked its apogee.
A Brief History of Time from the Big Bang to Black Holes, by the Cambridge cosmologist Stephen Hawking, had been five years in the making and in some senses was just as much the work of Peter Guzzardi, a New York editor with Bantam Books.15 It was Guzzardi who had persuaded Hawking to leave Cambridge University Press. CUP had been planning to publish Hawking’s book, because they had published his others, and had offered an advance of £10,000 – their biggest ever. But Guzzardi tempted Hawking to Bantam, though it perhaps wasn’t too difficult a choice for the scientist, since the firm’s editorial board had been won over by Guzzardi’s enthusiasm, to the point of offering a $250,000 advance. In the intervening years, Guzzardi had worked hard to make Hawking’s dense prose ever more accessible for a general audience.16 The book was released in early spring 1988 – and what happened then quickly passed into publishing history. More than half a million hardback copies of the book were sold in both the United States and Britain, where the title went through twenty reprints by 1991 and remained in the best-seller lists for no fewer than 234 weeks, four and a half years. The book was an almost equally great success in Italy, Germany, Japan, and a host of other countries across the world, and Hawking quickly became the world’s most famous scientist. He was given his own television series, made cameo appearances in Hollywood films, and his public lectures filled theatres the size of the Albert Hall in London.17
There was one other unusual element in this story of success. In 1988 Hawking was aged forty-six, but since 1963, when he was twenty-one, he had been diagnosed as suffering from amyotrophic lateral sclerosis, ALS, also known (in the U.K.) as motor neurone disease and (in the United States) as Lou Gehrig’s disease, after the Yankee baseball player who died from it.18 What had begun as mere clumsiness at the end of 1962 had progressed over the intervening years so that by 1988 Hawking was confined to a wheelchair and able to communicate only by means of a special computer connected to a voice synthesiser. Despite these handicaps, in 1979 he had been appointed Lucasian Professor of Mathematics at Cambridge, a post that Isaac Newton had held before him, he had won the Einstein medal, and he had published a number of well-received academic books on gravity, relativity, and the structure of the universe. As Hawking’s biographers say, we shall never know to what extent Stephen Hawking’s considerable disability contributed to the popularity of his ideas, but there was something triumphant, even moving, in the way he overcame his handicap (in the late 1960s he had been given two years to live). He has never allowed his disability to deflect him from what he knows are science’s central intellectual concerns. These involve black holes, the concept of a ‘singularity,’ and the light they throw on the Big Bang; the possibility of multiple universes; and new ideas about gravity and the fabric of reality, in particular ‘string theory.’
It is with black holes that Hawking’s name is most indelibly linked. This idea, as mentioned earlier, was first broached in the 1960s. Black holes were envisaged as superdense objects, the result of a certain type of stellar evolution in which a large body collapses in on itself under the force of gravity to the point where nothing, not even light, can escape. The discovery of pulsars, quasars, neutron stars, and background radiation in the 1960s considerably broadened our understanding of this process, besides making it real, rather than theoretical. Working with Roger Penrose, another brilliant physicist then at Birkbeck College in London, this pair first argued that at the centre of every black hole, as at the beginning of the universe, there must be a ‘singularity,’ a moment when matter is infinitely dense, infinitely small, and when the laws of physics as we know them break down. Hawking added to this the revolutionary idea that black holes could emit radiation (this became known as Hawking radiation) and, under certain conditions, explode.19 He also believes that, just as radio stars had been discovered in the 1960s, thanks to new radio-telescopes, so X rays should also be detectable from space via satellites above the atmosphere, which otherwise screened out such rays. Hawking’s reasoning was based on calculations that showed that as matter was sucked into a black hole, it would get hot enough to emit X rays. Sure enough, four X-ray sources were subsequently identified in a survey of the heavens and so became the first candidates for observable black holes. Hawking’s later calculations showed that, contrary to his first ideas, black holes did not remain stable but lost energy, in the form of gravity, shrank, and eventually, after billions of years, exploded, possibly accounting for occasional and otherwise unexplained bursts of energy in the universe.20
In the 1970s Hawking was invited to Caltech, where he met and conferred with the charismatic Richard Feynman.21 Feynman was an authority on quantum theory, and Hawking used this encounter to develop an explanation of how the universe began.22 It was a theory he unveiled in 1981 in, of all places, the Vatican. The source of Hawking’s theory was an attempt to conceive what would happen when a black hole shrank to the point where it disappeared, the troublesome fact being that, according to quantum theory, the smallest theoretical length is the Planck length, derived from the Planck constant, and equal to io–35 metres. Once something reaches this size (and though it is very small, it is not zero), it cannot shrink further but can only disappear entirely. Similarly, the Planck time is, on the same basis, 10–43 of a second, so that when the universe came into existence, it could not do so in less time than this.23 Hawking resolved this anomaly by a process that can best be explained by an analogy. Hawking asks us to accept, as Einstein said, that space-time is curved, like the skin of a balloon, say, or the surface of the earth. Remember that these are analogies only; using another, Hawking said that the size of the universe at its birth was like a small circle drawn around, say, the North Pole. As the universe – the circle – expands, it is as if the lines of latitude are expanding around the earth, until they reach the equator, and then they begin to shrink, until they reach the South Pole in the ‘Big Crunch.’ But, and this is where the analogy still holds in a useful way, at the South Pole, wherever you go you must travel north: the geometry dictates that it cannot be otherwise. Hawking asks us to accept that at the birth of the universe an analogous process occurred – just as there is no meaning for south at the South Pole, so there is no meaning for before at the singularity of the universe: time can only go forward.
Hawking’s theory was an attempt to explain what happened ‘before’ the Big Bang. Among the other things that troubled physicists about the Big Bang theory was that the universe as we know it appears much the same in all directions.24 Why this exquisite symmetry? Most explosions do not show such perfect balance – what made the ‘singularity’ different? Alan Guth, of MIT, and Andrei Linde, a Russian physicist who emigrated to the United States in 1990, argued that at the beginning of time – i.e., T = 10–43 seconds, when the cosmos was smaller even than a proton – gravity was briefly a repulsive force, rather than an attractive one. Because of this, they said, the universe passed through a very rapid inflationary period, until it was about the size of a grapefruit, when it settled down to the expansion rate we see (and can measure) today. The point of this theory (some critics call it an ‘invention’) is that it is the most parsimonious explanati
on required to show why the universe is so uniform: the rapid inflation would have blown out any wrinkles. It also explains why the universe is not completely homogeneous: there are chunks of matter, which form galaxies and stars and planets, and other forms of radiation, which form gases. Linde went on to theorise that our universe is not the only one spawned by inflation.25 There is, he contends, a ‘megaverse,’ with many universes of different sizes, and this was something that Hawking also explored. Baby universes are, in effect, black holes, bubbles in space-time. Going back to the analogy of the balloon, imagine a blister on the skin of the balloon, marked off by a narrow isthmus, equivalent to a singularity. None of us can pass through the isthmus, and none of us is aware of the blister, which can be as big as the balloon, or bigger. In fact, any number may exist – they are a function of the curvature of space-time and of the physics of black holes. By definition we can never experience them directly: they have no meaning.
That phrase, ‘no meaning,’ introduces the latest phase of thinking in physics. Some critics call it ‘ironic science,’ speculation as much as experimentation, where there is no real evidence for the (often) outlandish ideas being put forward.26 But that is not quite fair. Much of the speculation is prompted – and supported – by mathematical calculations that point toward solutions where words, visual images and analogies all break down. Throughout the twentieth century physicists have come up with ideas that have only found experimental support much later, so perhaps there is nothing very new here. At the moment, we are living at an in-between time, and have no way of knowing whether many of the ideas current in physics will endure and be supported by experiment. But it seems unlikely that some ever will be.
Another theory of scientists like Hawking is that ‘in principle’ the original black hole and all subsequent universes are actually linked by what are variously known as ‘wormholes’ or ‘cosmic string.’27 Wormholes, as conceived, are minuscule tubes that link different parts of the universe, including black holes, and therefore in theory can act as links to other universes. They are so narrow, however (a single Planck length in diameter), that nothing could ever pass through them, without the help of cosmic string – which, it should be stressed, is an entirely theoretical form of matter, regarded as a relic of the original Big Bang. Cosmic string also stretches across the universe in very thin (but very dense) strips and operates ‘exotically.’ What this means is that when it is squeezed, it expands, and when it is stretched, it contracts. In theory at least, therefore, cosmic string could hold wormholes open. This, again in theory, makes time travel possible, in some future civilisation. That’s what some physicists say; others are sceptical.
Martin Rees’s ‘anthropic principle’ of the universe is somewhat easier to grasp. Rees, the British astronomer royal and another contemporary of Hawking, offers indirect evidence for ‘parallel universes.’ His argument is that for ourselves to exist, a very great number of coincidences must have occurred, if there is only one universe. In an early paper, he showed that if just one aspect of our laws of physics were to be changed – say, gravity was increased – the universe as we know it would be very different: celestial bodies would be smaller, cooler, would have shorter lifetimes, a very different surface geography, and much else. One consequence is that life as we know it can in all probability only form in universes with the sort of physical laws we enjoy. This means, first, that other forms of life are likely elsewhere in the universe (because the same physical laws apply), but it also means that many other universes probably exist, with other physical laws, in which very different forms of life, or no forms of life, exist. Rees argues that we can observe our universe, and conjecture others, because the physical laws exist about us to allow it. He insists that this is too much of a coincidence: other universes, very different from ours, almost certainly must exist.28
Like most senior physicists, cosmologists, and mathematicians, Hawking has also devoted much energy to what some scientists call ‘the whole shebang,’ the so-called Theory of Everything. This too is an ironic phrase, referring to the attempt to describe all of fundamental physics by one set of equations: nothing more. Physicists have been saying this ‘final solution’ is just around the corner for more than a decade, but in fact the theory of everything is still elusive.29 To begin with, before the physics revolution discussed in earlier chapters of this book, two theories were required. As Steven Weinberg tells the story, there was Isaac Newton’s theory of gravity, ‘intended to explain the movements of the celestial bodies and how such things as apples fall to the ground; and there was James Clerk Maxwell’s account of electromagnetism as a way to explain light, radiation, magnetism, and the forces that operate between electrically charged particles.’ However, these two theories were compatible only up to a point: according to Maxwell, the speed of light was the same for all observers, whereas Newton’s theories predicted that the speed measured for light would depend on the motion of the observer. ‘Einstein’s general theory of relativity overcame this problem, showing that Maxwell was right.’ But it was the quantum revolution that changed everything and made physics more beautiful but more complex at the same time. This linked Maxwell’s theory and new quantum rules, which viewed the universe as discontinuous, with a limit on how small the packets of electromagnetic energy can be, and how small a unit of time or distance is. At the same time, this introduced two new forces, both operating at very short range, within the nucleus of the atom. The strong force holds the particles of the nucleus together and is very strong (it is this energy that is released in a nuclear weapon). The other is known as the weak force, which is responsible for radioactive decay.
And so, until the 1960s there were four forces that needed to be reconciled: gravity, electromagnetism, the strong nuclear force, and the weak radioactive force. In the 1960s a set of equations was devised by Sheldon Glashow, and built on by Abdus Salam and Steven Weinberg, at Texas, which described both the weak force and electromagnetism and posited three new particles, W+, W– and Z0.30 These were experimentally observed at CERN in Geneva in 1983. Later on, physicists developed a series of equations to describe the strong force: this was related to the discovery of quarks. Having been given rather whimsical names, including those of colours (though of course particles don’t have colours), the new theory accounting for how quarks interact became known as quantum chromodynamics, or QCD. Therefore electromagnetism, the weak force, and the strong force have all been joined together into one set of equations. This is a remarkable achievement, but it still leaves out gravity, and it is the incorporation of gravity into this overall scheme that would mark, for physicists, the so-called Theory of Everything.
At first they moved toward a quantum theory of gravity. That is to say, physicists theorised the existence of one or more particles that account for the force and gave the name ‘graviton’ to the gravity particle, though the new theories presuppose that many more than one such particle exists. (Some physicists predict 8, others 154, which gives an idea of the task that still lies ahead.) But then, in the mid-1980s, physics was overtaken by the ‘string revolution’ and, in 1995, by a second ‘superstring revolution.’ In an uncanny replay of the excitement that gripped physics at the turn of the twentieth century, a whole new area of inquiry blossomed into view as the twenty-first century approached.31 By 1990 the shelves of major bookstores in the developed world were filled with more popular science books than ever before. And there were just as many physics, cosmology, and mathematics volumes as there were evolution and other biology titles. As part of this phenomenon, in 1999 a physics and mathematics professor who held joint appointments at Cornell and Columbia Universities entered the best-seller lists on both sides of the Adantic with a book that was every bit as difficult as A Brief History of Time, if not more so. The Elegant Universe: Superstrings, Hidden Dimensions and the Quest for the Ultimate Theory, by Brian Greene, described the latest excitements in physics, working hard to render very difficult concepts accessible (Greene, not to put his
readers off, called these difficult subjects ‘subtle’).32 He introduced a whole new set of physicists to join the pantheon that includes Einstein, Ernest Rutherford, Niels Bohr, Werner Heisenberg, Erwin Schrödinger, Wolfgang Pauli, James Chadwick, Roger Penrose, and Stephen Hawking. Among these new names Edward Witten stands out, together with Eugenio Calabi, Theodor Kaluza, Andrew Strominger, Stein Strømme, Cumrun Vafa, Gabriele Veneziano, and Shing-Tung Yau, about as international a group of names as you could find anywhere.
The string revolution came about because of a fundamental paradox. Although each was successful on its own account, the theory of general relativity, explaining the large-scale structure of the universe, and quantum mechanics, explaining the minuscule subatomic scale, were mutually incompatible. Physicists could not believe that nature would allow such a state of affairs – one set of laws for large things, another for small things – and for some time they had been seeking ways to reconcile this incompatibility, which many felt was not unrelated to their failure to explain gravity. There were other fundamental questions, too, which the string theorists faced up to: Why are there four fundamental forces?33 Why are there the number of particles that there are, and why do they have the properties they do? The answer that string theorists propose is that the basic constituent of matter is not, in fact, a series of particles – point-shaped entities – but very tiny, one-dimensional strings, as often as not formed into loops. These strings are very small – about 10–33 of a centimetre – which means that they are beyond the scope of direct observation of current measuring instruments. Notwithstanding that, according to string theory an electron is a string vibrating one way, an up quark is a string vibrating another way, and a tau particle is a string vibrating in a third way, and so on, just as the strings on a violin vibrate in different ways so as to produce different notes. As the figures show, we are dealing here with very small entities indeed – about a hundred billion billion (1020) times smaller than an atomic nucleus. But, say the string theorists, at this level it is possible to reconcile relativity and quantum theory. As a by-product and a bonus, they also say that a gravity particle – the graviton – emerges naturally from the calculations.