In the late 1980s, when I first wrote about Stephen Hawking, it seemed inappropriate – indeed impossible – to describe details of the Hawkings’ private lives that only a very few people knew. All of this hidden information became public knowledge in 1999 with the publication of Jane Hawking’s Music to Move the Stars. She was unsparingly frank about her memories of the physical and emotional turmoil of their lives and about her relationship with Jonathan Hellyer Jones. It surprised hardly anyone that Jane’s book caused a sensation in the media, but all the furore did seem to come as something of a shock to Jane. Hawking made no public comment except that he never read biographies about himself. His humour survived, as witness his reply to a reporter asking him about Jane’s book, who also asked whether he had willed his DNA to science for cloning: ‘I don’t think anyone would want another copy of me.’20
Hawking had appeared in an opera and on television, and had a film made about him. He had not yet been a character in a play. When he received an advance script of Robin Hawdon’s God and Stephen Hawking, his reaction was to ignore it in the hope it would go away and never reach the stage. When Hawdon added details from Jane’s book, Hawking considered taking legal action but decided that would just attract more attention to a play that was ‘stupid and worthless’.21 God, the Pope, the Queen, Jane Hawking, Einstein and Newton were also characters. Lucy saw a performance and, watching her family portrayed on stage, found herself both ‘horrified and mesmerized’, fighting an ‘insane urge to climb on the stage and join them’.22
Meanwhile, Hawking was broadening his horizons in a different direction at the behest of his son Tim, now a university student in Exeter. Unlike his older brother, Tim had not followed his father into physics but instead was studying French and Spanish as his mother had done. Tim managed to interest his father in Formula One racing and even enticed him to rock concerts. Hawking claimed he really enjoyed some of these, but he left one concert for which the tickets had been particularly difficult to obtain after only twenty minutes. This life-long Wagner fan (though his speech synthesizer insisted on pronouncing it ‘Werner’ or ‘Wagoner’) was also a discerning enough rock fan to know what he liked and what not – and vote with his wheels.
A Meeting of Theories – No Boundaries and Inflation
In the late 1990s, as the end of the millennium approached, Hawking’s reputation among his colleagues and his public celebrity seemed secure, but his and Jim Hartle’s no-boundary proposal was still controversial. It predicted a closed universe, the first of Friedmann’s models (see Figure 6.1). In that model, the universe would eventually collapse to a Big Crunch. The discovery that the expansion of the universe is speeding up, and better-informed estimates of the amount of matter and energy in the universe, were increasingly causing theorists in the late 1990s to doubt the possibility that ours is that kind of universe. It was even looking likely to be an ‘open’ universe, Friedmann’s second model, which expands for ever.
At the same time, inflation theory was predicting that the universe is ‘flat’, Friedmann’s third model, meaning that the amount of matter in it is just right, not too much and not too little, to cause the universe to expand only barely fast enough to avoid collapse. In 1995, Neil Turok, Martin Bucher and Alfred Goldhaber at the State University of New York Stony Brook had written a paper showing that inflation did not necessarily rule out an open universe, expanding for ever – but this was no immediate help for the no-boundary proposal.23
With his no-boundary proposal predicting a closed universe, inflation theory a flat or perhaps open one, and observations leaning towards an open one, Hawking began to consider the possibility of bringing these models into agreement. Neil Turok was a good friend, and over cups of tea one day after a Cambridge seminar on open inflation the two began sharing ideas.
The upshot was a model in which a particle of space and time resembling an extremely small, slightly irregular, wrinkled sphere in four dimensions would automatically inflate itself into an infinite, open universe.24 Because this particle would have lasted for only an instant before undergoing inflation, just a flash in the pan, so to speak, Hawking and Turok named it the ‘instanton’. But ‘pea’ was the name that caught on with the public, because the two theorists announced that though it was unimaginably tinier than a pea, it had the mass of a pea (about one gram). The pea image was also useful because a pea is round, which goes nicely with the rounded ‘origin’ of the universe, where time was like a fourth dimension of space, in the no-boundary proposal. A pea is not a singularity. Not a point of infinite density. In Neil Turok’s words:
Think of inflation as being the dynamite that produced the big bang. Our instanton is a sort of self-lighting fuse that ignites inflation. To have our instanton, you have to have gravity, matter, space and time. Take any one ingredient away, and our instanton doesn’t exist. But if you have an instanton, it will instantly turn into an inflating, infinite universe.25
Nothing existed ‘outside’ the instanton, and nothing existed ‘before’ it. In both time and space, it was all there was. However, claims in the media that this theory showed how the universe sprang into being from nothing were far from the mark. It sprang into being from a ‘combination of gravity, space, time, and matter packed into a rounded minuscule object’.26
It was a good try, bringing together inflation theory, the no-boundary condition and observational evidence, but it was not an immediate hit with Hawking’s and Turok’s colleagues. One rather embarrassing problem was that many of the possible universes the model predicted had no matter in them at all. That, however, was not too difficult for Hawking to remedy. One could use the anthropic principle and say that, in fact, only one of the possible universes had to support the existence of intelligent life forms.
Criticism came from those who found the no-boundary proposal still too controversial to be used dependably as part of a meaningful theory. Others thought Hawking and Turok were relying too heavily on the anthropic principle. Andrei Linde was very critical. To his way of thinking, a model with universes that included at best only about one-thirtieth the density of matter currently observed in our universe was unacceptable. Not even the anthropic principle could save it. Hawking and Turok responded: so far they had been working with only a very simple model. A more realistic model would yield better results.
Because of public interest in any news having to do with Hawking, the media on both sides of the Atlantic picked up the disagreement and treated it as though the theoretical-physics world were staging its own Clash of the Titans. ‘Give Peas a Chance!’27 urged Astronomy Magazine, while Science showed more restraint with ‘Inflation Confronts an Open Universe’.28 The online news service at Stanford, where Linde was a professor, announced it like a prize fight: ‘Hawking, Linde Spar over Birth of the Universe’.29 Hawking’s name headed that title, even though Linde was now a local boy, but perhaps Stanford Report Online had decided that no one could be faulted for sticking to alphabetical order.
If Linde had once found Hawking intimidating, that was no longer the case. He called Hawking ‘an extremely talented person’,30 ‘a very brilliant man’,31 but also commented that Hawking’s faith in mathematics bordered on a religion,32 and that ‘Sometimes – this is my interpretation – he trusts mathematics so much that he makes calculations first and interprets them later.’33 ‘You need to make sure that you are applying the mathematics correctly. In this case, my intuition tells me that he has not done so.’34 In one highly complimentary statement, however, Linde echoed what many others have said about Hawking: ‘I consider Stephen my friend and I hope we will remain friends after this is over. A number of times he has come up with surprising conclusions that at first seem like they are wrong. But in several instances he turned out to be right. In other cases, he was wrong. We will just have to wait and see which it is this time.’35
The article in the Stanford online news was triggered by a seminar Hawking gave at Stanford in April, at Linde’s invitation. The prospect
of witnessing these two men ‘sparring’ in person brought out a mammoth crowd. Hawking also debated with Linde and Alexander Vilenkin the next November in Monterey, California, this time defending his employment of the anthropic principle with a confidence that foreshadowed the much stronger use he would make of it in the future: ‘The universe we live in didn’t collapse early on or become almost empty. So we have to take account of the anthropic principle: if the universe hadn’t been suitable for our existence, we wouldn’t be asking why it is the way it is.’36 When it came to Hawking’s and Turok’s proposal, the jury would be out a long time.
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‘It seems clear to me’
IN DECEMBER 1999, on the eve of the millennium, CNN’s Larry King came in person to Cambridge to the DAMTP to film an interview with Hawking, who carefully programmed the answers to prearranged questions into his computer to avoid any delay in replying. The interview was broadcast on Christmas Day. When Larry King asked him how he planned to celebrate this special New Year, Hawking replied that he was going to a Simpsons-character costume party, dressed as himself. This would not require a costume.1
The millennium found Hawking playing in the big leagues. He joined international luminaries – among them Archbishop Desmond Tutu – in signing a ‘Charter for the Third Millennium on Disability’. In May 2000 he took issue with Prince Charles for opposing genetically modified food, and in August he recorded a televised tribute to US presidential candidate Al Gore, to be shown at the Democratic National Convention in the United States.
His speaking engagements for audiences numbering in the thousands were continuing to take him worldwide, to South Korea, to Mumbai and Delhi in India, to Granada in Spain. He delivered a lecture at Caltech for Kip Thorne’s sixtieth-birthday ‘KipFest’ in June 2000, and another back home in Cambridge that raised thousands of pounds for the Newnham Croft Primary School to build a new extension. In the summer of 2001 a new documentary, The Real Stephen Hawking, aired on BBC4. Hawking called public attention to the need for new technology for the disabled by agreeing to advertise the Quantum Jazzy 1400 Wheelchair. ‘It will keep my nurses fit as they try to keep up,’ he quipped, and that was no exaggeration.
‘Try to keep up’ they did. A trip abroad was, and is, like an army on the move: Hawking, his graduate assistant, a medical nurse, and two carers are the minimum. The amount of equipment and luggage that go with them has been prodigious ever since the 1980s, when he began travelling with the computer and apparatus with which he communicates. Joan Godwin, who oversaw the transportation of all this paraphernalia back and forth across the world many times, says it includes the usual suitcases for clothing, the vital suction equipment for keeping his breathing passages open, and an extremely heavy black bag containing everything that might be necessary in case of an emergency. His graduate assistant brings along tools and equipment and spare parts necessary for maintenance and emergency repairs to the wheelchair and computer. Not surprisingly these items sometimes get lost in transit. Godwin recalls the crisis and emergency shopping trip when the suitcase with all Hawking’s clothes got shoved aside by baggage handlers and never made it to the next stop, where he was scheduled to meet Bill Gates. On another occasion, when she wasn’t along on the journey, she received a frantic phone call from his staff on the other side of the world. The suction equipment was locked in a car and the keys lost. What should they do?
Since the millennium, Hawking has been flying whenever possible by private jet. On a commercial flight, the wheelchair had to travel inside the plane to avoid a lengthy wait for him on the otherwise deserted plane until the baggage was brought out and the chair brought to him. It had even happened that the chair had its own first class seat. Security checks have been a perennial problem because the chair won’t fit through the metal detector. Most of the time no one insists on searching him. It isn’t only planes that are a challenge. Complicated special arrangements had to be made for the ‘bullet train’ in Japan to stop for an extra thirty seconds.
Not long after the millennium, some of the same press that excitedly described all this coming and going and Hawking’s public appearances and honours seemed equally eager to report rumours that he was suffering mysterious physical abuse. When the Cambridge police initiated an investigation, Hawking resolutely refused to have any part in it. He dismissed the sometimes frantic concerns of staff and family, and firmly let it be known to police and all others that he wanted no interference in his and his wife’s life. Intermittent investigations, rumours, and police interviews of colleagues, staff and family regarding an alleged series of ‘unexplained injuries’, some of them allegedly life-threatening, went on for five years until, in March 2004, the police dropped the investigation.
P-branes aren’t So Dumb
The millennium and the years immediately following found Andrei Linde and his collaborators working to connect string theory with the multiverse of eternal inflation, while Hawking and some of his current and former graduate students were putting their heads together (when Hawking’s head wasn’t off in some remote part of the world) to bring the no-boundary proposal and a relatively new idea called ‘brane’ theory into line with one another. They were also continuing to look at black holes in the light of brane theory.
The name ‘p-brane’ was coined by Peter Townsend, one of Hawking’s colleagues in the DAMTP who did fundamental work on these theoretical oddities. The ‘p’ in p-brane can be any number, the number indicating how many dimensions the ‘brane’ has. If p = 1, that’s a 1-brane. It has one dimension, length. It’s a string. If p = 2, that’s a 2-brane. It has two dimensions, length and width. It’s a sheet or membrane. Continuing in this vein, we might decide that the infamous, deadly ‘gelatinous cube’ of some adventure games must be a 3-brane – though that isn’t part of the theory. Higher numbers for p are possible as well. They are more difficult to picture. The scheme is reminiscent of an idea that had emerged in the fifth century BC with the Pythagoreans and was later picked up by Plato, that the world is created in a progression from point to line to surface to solid. Plato speculated that there might be more dimensions to the progression after that, but these were all that were needed to have the world we know.2 Modern p-brane theorists are far less restrained when it comes to considering those extra dimensions.
P-branes can absorb and emit particles in the same way black holes do. At least for certain types of black holes, the p-brane model predicts the same emission rate that Hawking’s virtual particle-pair model predicts.
The p-branes provide a sort of storage facility for information that falls into a black hole, but they might do better than that: the information emerges eventually in the radiation from the p-branes. Considering this possibility, Hawking was thinking again about the implication of the Heisenberg uncertainty principle that every region of space must be full of tiny black holes that appear and disappear as rapidly as the particle pairs in Hawking radiation. These little chaps gobble up particles and information. Of course, they are a hundred trillion times smaller than an atomic nucleus. Nibble might be a better word, which is why, said Hawking, the laws of physics still appear deterministic for everyday intents and purposes. That does not, however, mean the loss of information is any less serious. Could p-branes come to the rescue?
After Hawking’s 1981 announcement that information is lost from the universe in black holes, the controversy about the information paradox had continued, though – surprisingly, given the significance of the issue for physics – not at a level that appeared to disturb Hawking or get a rise out of him as his thoughts turned to other matters. Some wondered whether he was simply being stubborn, choosing to ignore interesting arguments that contradicted his own ideas, refusing to move ahead and engage in the discussion. A few feared that he was simply not well enough to respond in a forceful and meaningful way. To him it seemed he had delivered the unassailable verdict, as unfortunate as that verdict was, and none of the arguments he was hearing were significant enough to pull hi
m into the fray.
However, the boss had not been asleep. He knew of Susskind’s proposal in 1993; and the p-brane suggestion for solving the information paradox, coming in 1996 from physicists Andrew Strominger and Cumrun Vafa, had definitely caught his attention. Hawking and his colleagues considered that solution to the information loss problem, and some had hopes for it. The giant stirred in his lair a little, but then turned over and remained unconvinced. Hawking stuck to his guns. Information is irretrievably lost in black holes. P-branes – though interesting for other reasons – were not the answer. Nevertheless, when Hawking closed a lecture with the words, ‘The future of the universe is not completely determined by the laws of science and its present state as Laplace thought, God still has a few tricks up his sleeve’, and the last slide was a drawing showing an elderly, bearded figure with an enigmatic smile, slipping playing cards into the sleeve of his robe, one wondered … were those cards 2-branes?
A Prehistory of the ‘Nutshell’
The first I saw or heard of The Universe in a Nutshell was as a bundle of typewritten pages, sent to me by Ann Harris, Hawking’s editor at Bantam in New York in the summer of 2000. There were print-outs of public and scientific lectures and papers, most of them recent, some easy to understand, some full of equations and the language of physics, repetitious of one another in places and occasionally of previous Hawking books – not resembling a coherent book at all. Here were string theory, M-theory, imaginary time, sums-over-histories, the information paradox, the holographic principle, extra dimensions, not to mention summaries of more basic subjects such as quantum mechanics, general relativity, black holes and the Big Bang. It was an awful lot of material and it definitely was not in a nutshell … yet. Could it possibly make a book, Ann Harris wanted to know. Stephen Hawking was one of the jewels in her and Bantam’s crown. It was unthinkable to send this back to him and say it couldn’t be published.
Stephen Hawking, His Life and Work Page 26