Spot the odd one out: Albert Einstein, Sir Isaac Newton, James Clerk Maxwell, Niels Bohr, Werner Heisenberg, Stephen Hawking. Did you get it? Of course, the answer is Professor Hawking. Why? Well, the others are all dead; and are also the top five physicists of all time, as voted by their peers in a 1999 survey by Physics World, the house magazine for physicists.
But Professor Hawking didn't come sixth. In fact, he wasn't even the highest-ranked living physicist when his peers came to vote; that honour went to Hans Bethe (a Nobel prizewinner who, in the 1930s, deduced the nuclear reactions that power stars). He wasn't even the second-ranked living physicist. About 10 other people were named as having been just as important in their contributions to the science that attempts to explain how the universe works. Professor Hawking was way down the rankings, well outside the top 10.
So, why is it then that the average member of the public is sure that Professor Hawking, 60 next January, who since 1979 has held the chair of Lucasian Professor of Mathematics at Cambridge University, is simply the most brilliant scientist ever since Einstein? Why is it he who gets cameos on Star Trek and The Simpsons, and has fireside chats with the President of the United States (as he did in 1998), when most of his colleagues – including Professor Bethe – labour in comparative obscurity, in ageing facilities, doodling equations on blackboards and computer screens? And what do the physicists themselves think of that difference?
Ask around, and you begin to get the impression that there are people whose feathers are ruffled by Professor Hawking's fame. Peter Coles, professor of astronomy at the University of Nottingham, says: "Coffee-time talks in physics departments often come up with the same topic: it's very difficult to get anybody to say anything critical of him. But to have somebody like that in an establishment that runs on peer review isn't healthy. The trouble is, people fear that they will be thought of as jealous."
However, Bernard Carr, a friend of Hawking's who is professor of astronomy at Queen Mary College, London, says: "The fact is, he is a great physicist. To say he's the greatest since Einstein is an exaggeration, but he's a cult figure with the public, and that has to be good for the subject."
"There's a difference between views inside the physics community and outside," says Peter Rodgers, editor of Physics World. "Inside, he's recognised for a couple of important works, but he has never set himself up as the new Newton or anything. But outside, he's famous because of that book."
Which book? Why, A Brief History of Time, of course, his 1988 blockbuster that has sold more than 10 million copies and been turned into a TV series. There's probably a copy of the book in every aspirational middle-class home, and equally probably, the last 20 pages remain unperused by human eyes. Brief History must rank alongside James Joyce's Finnegans Wake, as the most regularly unfinished book.
It's worth noting that, when it was published, the reviews were not rapturous. A reviewer in The Economist described it as a "not-altogether-satisfactory explanation, to the layman, of the ideas that have earned him so much respect among his colleagues... the presentation is disappointing... there is little sense of how and why people chose to ask the questions to which the book provides simplified answers".
That didn't stop it taking off, and even defining a genre of books that people buy but don't actually read: "social furniture". Now he has written another one, called The Universe in a Nutshell, which is being pushed as a "very optimistic" look at the future. The publishers are preparing a huge marketing push to promote it, with advertising campaigns in trade magazines and bookshops. They are also keen to emphasise that this time, it is a reader-friendly book.
But when it arrives in November, can it possibly elevate his status any further? Or will it lead to the reverse, as inevitably happens to those caught in the spiral of fame, where the upward path abruptly turns downward?
Hawking himself has long been protected from the usual intrusions of celebrity by the combination of his subject matter and his disability. While many people can argue about whether or not Victoria Beckham can sing in key, only top-flight physicists are in a position to determine whether black holes are really able to emit heat (so-called "Hawking radiation", predicted in a paper by him in 1975).
His disability, the result of motor neurone disease (MND), marks him out and, many believe, has given him the pre-eminence in the public eye that he would never have had if he were just an average dishevelled physics teacher in a provincial university who happened to write an interesting but impenetrable book. Confined to a wheelchair, able to communicate only through a computerised voice (now a baritone rather than his former android burr), where he must laboriously type each answer, he has become iconic.
"He's instantly recognisable," says Professor Coles. "That also made Einstein famous. He's unique in the way he has to communicate, and the fact that he's suffered this illness most of his adult life. That means that there's sympathy, and people also marvel that he has done so much."
He has also escaped many of the other trappings of fame – such as tabloid fascination with his private life. This, despite a love life worthy of Robin Cook. In 1990, he left Jane, his wife of 30 years, to move in with Elaine Mason – one of his nurses, whose former husband had developed the voice synthesiser that provided Hawking's "voice". In 1995, the pair married quietly. Last year, when police were alerted to a series of mysterious injuries sustained by Hawking, he refused to make a statement and the matter was dropped by the police and the press.
Then, in 1999, his former wife published Music To Move The Stars: My Life with Stephen, in which she detailed the grind of being married to someone who needed constant care while she also looked after a young family (Hawking has three children and a grandchild); of how her Christian faith clashed with his steadfast atheism; of how she felt increasingly sidelined as his fame grew following the book's publication. "Outside the marriage, and apart from Stephen, I was nothing," she wrote. He then began a relationship with Ms Mason.
News of the affair always generates the same reaction: not "why?" but "how?" But that follows from the natural belief that because Hawking is paralysed, he is helpless. In fact, he is known for an incisive wit; the story is told of how he gave a physics talk at a London university, and then went out for a curry with some friends there. The head of department was talking about how some of the students had been ringing phone sex lines, and showed everyone the bill. Abruptly, the sound of a lesbian tryst began issuing from the loudspeaker on Hawking's chair: he had dialled one of the numbers from the bill on his onboard phone. "He had everybody laughing," recalls one. "There was not much movement in his face, but there was a real smile in his eyes."
It is worth noting that he is not above manipulating people's thinking about him to his benefit. The last line in A Brief History Of Time is famous for saying that, if we could tie together the equations describing the universe, we would "know the mind of God". But, as his former wife says, he is an atheist. So why is the deity making an appearance? The obvious answer is that it helps sell books. It is notable that in 1997, Professor Hawking admitted that he had been over-optimistic in predicting in 1980 that we would have such a "unified theory" by 2000; but, like a backgammon player, he then doubled, insisting that in 20 years, we would have. Quite what his contribution to that unified theory would be is unclear. Physics remains a discipline where theories are examined on their merits, not those of the writer; though it would not hurt a rising scientist to be linked with the Lucasian Professor. But the answers won't come from one very clever scientist, insists Professor Carr.
"The media like to think that there's just a few key people responsible for the big breakthroughs," he says. "In fact, there are hundreds of people working away at all the little problems that make up the big problem. The public likes to think that science progresses by big eureka moments. But it doesn't. In fact, it's a lot of little ones."
That doesn't mean, though, that some scientists don't use the press, and hype, to get more visibility, which leads to better grants for themselves and their employers. Moreover, Professor Hawking's iconic appearance has led to companies falling over themselves to sponsor him and Cambridge University. Microsoft has a research campus there, inspired by Nathan Myhrvold, formerly chief technology officer at the giant software corporation; he was a former student of Hawking's. Compaq also rushed to provide his onboard computer, confident that he would provide better visibility than any other scientist in the world.
Yet the spiral of celebrity is relentless. It troubles some scientists, who think he has become too famous. One was heard to grumble, while waiting to be interviewed for a scene in the TV series Stephen Hawking's Universe, that "It's not Stephen Hawking's..." Professor Coles says: "He deliberately places himself as a mystical figure: the things he works on are so far removed from everyday experience that people feel he's got an insight into the workings of the universe. And people find it thrilling. The idea that somebody can understand these things – well, they revere people who, they think, can understand the universe for them, when they can't."
Hawking himself says (on his personal website at www.hawking.org.uk): "I don't pay much attention to how journalists describe me. I know it is media hype. They need an Einstein-like figure to appeal to. But for them to compare me to Einstein is ridiculous. They don't understand either Einstein's work, or mine."
"It's like priests in medieval times," says Professor Coles. "They could do the understanding of God's work for the masses." Perhaps this then is the true face of God: not understanding – but passing off the job to someone else. In Stephen Hawking's case, it may be that we, the public, have found a true face of God: inscrutable, intelligent, and so remote that we can always put our own reading on to it.
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