Stephen Hawking (25 page)

Thinkers on both sides of the divide—those who support conventional religious views as well as the cynics and atheists—have quoted and misquoted Hawking on so many occasions that one writer recently compared his eloquence and quotability to that of Shakespeare or the Bible. Hawking scoffs at such suggestions, restating the fact that his quotability is derived from his succinctness, a talent he has had to nurture because of the difficulty he has communicating.

Hawking seems to have done little to help Jane through this crisis. She was, and perhaps still is, left exasperated by his stubbornness on the issue. “I pronounce my view that
there are different ways of approaching it [religion], and the mathematical way is only one way,” Jane has said, “and he just smiles.”
²⁹

It is not only conventional religion for which Hawking feels extreme skepticism. The lessons he learned from the ESP experiments in the fifties have never left him, and he has no time for mysticism or metaphysics in any shape or form. A number of writers have made attempts to bridge the gap between mysticism and late-twentieth-century physics. There are many who see parallels between Eastern religion and quantum mechanics, ancient teachings, and chaos theories, but Hawking pooh-poohs the whole scene. In his book
Lonely Hearts of the Cosmos
, Dennis Overbye describes an occasion when he met Hawking in the seventies and managed to steer him onto the topic of mysticism without getting his toes crushed. Overbye quoted the anthropologist Joseph Campbell on the Hindu goddess Kali, “the terrible one of many names whose stomach is a void and so can never be filled, whose womb is giving birth forever to all things.” He then tried to draw a connection between Kali and black holes. Barely able to contain himself, Hawking snorted:

It's fashionable rubbish. People go overboard on Eastern mysticism simply because it's something different that they haven't met before. But, as a natural description of reality, it fails abysmally to produce results. . . . If you look through Eastern mysticism you can find things that look suggestive of modern physics or cosmology. I don't think they have any significance.

Calling these things black holes was a master-stroke by Wheeler because it does make a [psychological]
connection, or conjure up a lot of human neuroses. If the Russian term “frozen star” had been generally adopted, then this part of Eastern mythology would not at all seem significant. They're named black holes because they relate to human fears of being destroyed or gobbled up. So in that sense there is a connection. I don't have fears of being thrown into them. I understand them. I feel in a sense that I'm their master.
³⁰

However, a number of journalists and commentators on the periphery of Hawking's world have made some quite ridiculous extrapolations on this theme. To some, Hawking is a metaphor for his own work, a black-hole astronaut himself. When Overbye put this to him, he was understandably ruffled by the suggestion.

“I've always found I could communicate,”
³¹
he snapped back, and went for Overbye's toes.

Black-hole astronaut or not, the amount Hawking traveled during the seventies was increasing each year. In the winter of 1976 he undertook an American tour, taking in talks at important conferences in Chicago and Boston. Even to other scientists who knew him from symposia and conferences around the globe, his speech was all but unintelligible, and when members of the general public and journalists were in attendance they found it almost as difficult to grapple with Hawking's speaking voice as with his subject matter.

Despite the fact that conference organizers were invariably forewarned of Hawking's disabilities, more often than not there would be no easy access to the stage in the lecture theater. He would have to make it there without ramps or lifts. On such occasions, Hawking's friends and colleagues
would come to his rescue, up to six of them manhandling his heavy wheelchair. Although Hawking himself weighed little more than ninety pounds, the chair ran on car batteries, which added to the weight, and, according to those who have taken part in these exercises, there was always the fear that they would drop him or that he would hurt his neck. One friend has described how he could see Hawking's head bobbing around as six of the biggest scientists in his group lifted the wheelchair five feet up onto the stage, and how he was terrified that one day something would go disastrously wrong, simply because the organizers hadn't thought things through.

Hawking made a great impression during his 1976 trip to the States. The stick-like figure hunched in his wheelchair was, to the vast majority of the audience, mumbling incomprehensibly, appearing to make his pronouncements to a point on the stage six feet in front of him. But despite this, those who came to hear him speak always took him very seriously. Close colleagues who could understand what he was saying translated for their neighbors as best they could, with one ear concentrating on the mathematics Hawking was describing. Slides and the relief of numerous corny jokes helped, but it was always hard work.

By this time, he had completely reversed his ideas about black holes and thermodynamics, the very ideas that had created such arguments a few years earlier. At a talk in Boston entitled “Black Holes Are White Hot,” he caused a stir with a conclusion refuting Einstein's famous statement “God doesn't play dice.” “God not only plays dice,” Hawking proclaimed, “he sometimes throws them where they can't be seen.”

Interviewers were queuing up to speak to Hawking. In January 1977, the BBC broadcast a program called
The Key
to the Universe
, with an accompanying book by Nigel Calder. The program was in large part devoted to Stephen Hawking's latest work and profiled the man and his efforts to unify general relativity and quantum mechanics—“the key to the Universe” of the title. For the first time, the general public was exposed to the thirty-five-year-old Dr. Stephen Hawking and the facts of his disability as well as his work. It had the British public watching in their millions.

From 1977, publicity surrounding Hawking and his achievements began to escalate on a local, national, and global scale. Between reports of punks signing record contracts in front of Buckingham Palace and growing excitement over the Queen's Jubilee that coming summer, there were mutterings in the Cambridge press about the odd fact that this famous scientist, a member of the Royal Society and black-hole celebrity, appearing on television and with his face in the papers on an increasingly regular basis, did not hold a professorial position at Cambridge University.

There were muted suggestions that perhaps the university was disinclined to give the severely disabled scientist a professorship because he might not live too long. By March 1977, however, the university had decided to offer him a specially created chair of gravitational physics, which would be his for as long as he remained in Cambridge; the same year, he was awarded the status of professorial fellow at Caius, a separate professorship bestowed by the college authorities.

The awards and honors continued to flood in. Robert Berman, Hawking's undergraduate supervisor at Oxford, had recommended him as an honorary fellow of University College. In his letter to the General Purposes Committee, he said:

The current issue of
Who's Who
shows some of his achievements, but cannot keep pace with the rate of award of honors.

I can't imagine that the College has ever produced a more distinguished scientist, and it would bring us honor if our association with his career were made manifest (the outside world assumes he is entirely a Cambridge product).

It might seem surprising to ask to consider someone not yet 35 as an Honorary Fellow, but there are two reasons for this. First, his distinction is quite exceptional and we don't have to wait for it to be generally recognized that he has made his mark. Hawking is mentioned in practically every article or lecture on black holes. His book (
The Large Scale Structure of Spacetime
) was what every cosmologist was waiting for.

Secondly, Hawking is gravely ill and is confined to a wheelchair with a type of creeping paralysis that normally cuts the lives of its victims very short. He is in an appalling physical state but his mind functions normally.

I hope that it won't be felt that we must wait to see whether he actually gets a Nobel Prize!

Berman thought that he might have to argue his case further. He was subsequently staggered when the recommendation was accepted without a single objection at the committee's first meeting.

The graffiti-daubing sluggard who, at Oxford University only sixteen years earlier, had spent more time drinking than working had come a very long way.

11

BACK TO THE BEGINNING

B
y the end of 1974, Hawking's work on black holes had shown that, using the general theory of relativity alone, the equations said that the surface area of a black hole could not shrink—but adding the quantum rules to the equations revealed that they could not only shrink but would eventually disappear in a puff of gamma radiation. His earlier work with Penrose had shown that, using the general theory of relativity alone, the equations said that the Universe must have been born out of a singularity, a point of infinite density and zero volume, at a time some 14 billion years ago. It was
natural that the next scientific question Hawking asked himself was what would happen to this prediction if the quantum rules were added to that set of equations.

This was no easy question to answer. Physicists had been trying to combine quantum theory and relativity theory into one complete, unified theory ever since the quantum revolution in the 1920s; Einstein himself spent the last twenty years of his working life on the problem and failed to come up with a solution. Indeed, a full theory of quantum gravity still eludes mathematicians. But by restricting himself to the specific puzzle of how relativity and quantum mechanics interacted at the beginning of time, Hawking was able to make progress, to such an extent that by the early 1980s he was posing the question of whether there ever had been a beginning to time at all. To understand how he arrived at this startling hypothesis, we have to look again at quantum theory, in a variation developed by the great American physicist Richard Feynman. It is known as the “sum-over-histories” or “path integral” approach.

The essential features of quantum mechanics are demonstrated most clearly in what is known as “the experiment with two holes.” In such an experiment, a beam of light, or a stream of electrons, is directed through two small holes in a wall and onto a screen on the other side. The version using light is known as Young's experiment and may be familiar from school physics. What happens is that the pattern of light on the screen forms a characteristic arrangement of dark and light stripes, caused when the electromagnetic waves passing through each of the holes interfere with each other. Where the two sets of waves add together, there is a bright stripe; where they cancel each other out, the screen is dark.

This interference is easy to understand in terms of waves. You can get exactly the same effect by making waves in a tank of water and letting them pass through two slits in a barrier. But it is much harder to understand how electrons, which we are used to thinking of as hard particles like tiny billiard balls, can behave in the same way. Yet they do.

What is even stranger is that the
same
pattern of dark and light stripes slowly builds up on the screen (which can be almost exactly the same as a TV screen) when electrons are fired through the holes
one at a time
. Why should this be strange? Think about what happens when electrons are fired through just one hole. Instead of a striped pattern on the screen, there is just a bright patch behind the hole. This is indeed what we see if we block off either of the two holes and fire the electrons through. “Obviously,” each electron can go through only one hole. But when
both
holes are open, even with electrons fired one at a time through the experiment, we do not see just two patches of brightness behind the holes, but the characteristic stripy pattern of Young's experiment.

This is the clearest example of the wave-particle duality (see
Chapter 2
) that lies at the heart of the quantum world. When each electron arrives at the screen, it makes a pinpoint of light, just as you would expect from the arrival of a tiny “billiard ball” particle. But when thousands of those points of light are added together, they produce the striped pattern corresponding to a wave passing through both holes at once. It is as if each individual electron is a wave that passes through both holes simultaneously, interferes with itself, decides which bit of the striped pattern it belongs in, and heads off there to arrive as a particle that makes a pinpoint of light.

Don't worry if you find this incomprehensible. Niels Bohr, one of the physicists who pioneered the quantum revolution, used to say that “anyone who is not shocked by quantum theory has not understood it,” while Feynman, probably the greatest theoretical physicist since the Second World War, went even further and was fond of saying that
nobody
understands quantum mechanics. The important thing is not to understand how such a strange behavior as wave-particle duality can occur, but to find a set of equations that describe what is going on and make it possible for physicists to predict how electrons, light waves, and the rest will behave. The sum-over-histories approach was Feynman's contribution to this more pragmatic form of “understanding” at the quantum level, and in the late 1970s Hawking applied it to the study of the Big Bang.

Feynman said that, instead of thinking of an object such as an electron as a simple particle that follows a single route from A to B (for example, through one of the two holes in Young's experiment), we have to regard it as following every possible path from A to B through spacetime. It would be easier for a “classical” particle to follow some paths (some “histories”) than others, and this is allowed for in Feynman's equations by assigning each path a probability, which can be calculated from the quantum rules.