No strings attached
YOU鈥橠 have thought that Roger Penrose would be pleased to have his work immortalised in an Oscar-nominated film. Apparently not. After friends told him about his book鈥檚 cameo in Happy Go Lucky, Penrose sat down to watch it. He didn鈥檛 have to wait long: his book appears in the opening sequence. The lead character is browsing in a bookshop. She pulls Penrose鈥檚 Road to Reality from a shelf, takes a look at the title and, putting it straight back, says, 鈥淥h, we don鈥檛 want to go there!鈥�
He is evidently disappointed by the treatment as, just for a moment, his bright, enthusiastic demeanour dims slightly. 鈥淚 thought she would have at least opened the book then closed it rapidly,鈥� he says. 鈥淏ut she didn鈥檛 even get that far.鈥� There鈥檚 a good reason for that: having a look inside the book might have derailed the film. Road To Reality clocks in at more than 1000 pages and is replete with intricate diagrams and terrifying equations. Its contents are pretty much indecipherable to almost everyone on the planet. Happy Go Lucky it is not.
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And yet 鈥� and here is the strange magic of Roger Penrose 鈥� it was a best-seller. Despite being impossibly successful in academia, Penrose seems to have the common touch. This is, after all, the mathematician who gave the artist M. C. Escher 鈥� also an esoteric yet popular figure 鈥� some of his best ideas. Penrose is also the mathematician most frequently mistaken for a physicist: in 1965 he produced the mathematics that showed how stars collapse to form black holes. More recently, Ed Witten, the founder of string theory, has been using another of Penrose鈥檚 creations 鈥� 鈥� to try to reduce string theory鈥檚 11 dimensions to a more manageable four.
Penrose, who is 80 next birthday, is still making incursions into physics. He has just handed his publisher the manuscript for his next book, a rewrite of cosmological theory. There are those, I hesitantly suggest, who say that mathematicians would normally have ceased being this productive long ago. 鈥淲ell,鈥� he says with a grin, 鈥淚 can鈥檛 help that, can I?鈥�
Indeed not; Penrose was born into a family of over-achievers. One brother is a chess grandmaster, another is a theoretical physicist and a fellow of the Royal Society. Their father was a professor of human genetics at University College London, and filled the house with a reverence for scholarship. One day, Penrose remembers, he came home from school and told his father his class would be learning calculus the following day. 鈥淭his terrified expression came over his face,鈥� Penrose recalls. 鈥淗e stopped what he was doing, took me over into the corner and taught me calculus. He didn鈥檛 want somebody else to have the pleasure of teaching his son something so wonderful.鈥�
And so it began. Where it will end is anyone鈥檚 guess, but Cycles of Time: An extraordinary new view of the universe is the next stop. The ideas in the book came to him five years ago, when he was worrying about the state of the universe. According to the standard view, dark energy will lead the universe into an eternal accelerating expansion. Every bit of matter will eventually lose contact with every other bit. 鈥淚t all just seemed unbelievably boring to me,鈥� Penrose says.
Then he found something interesting within it: at the very end of the universe, the only remaining particles will be massless. That means everything that exists will travel at the speed of light, making the flow of time meaningless. After a few mathematical manipulations of infinity, out popped a never-ending universe, where new big bangs are the inevitable result of a universe鈥檚 demise. In Penrose鈥檚 theory, one cosmos leads to another. 鈥淚 used to call it a crazy scheme, but I鈥檓 starting to believe it now,鈥� he says.
Penrose knows he is not the first to suggest endless loops of time. The , suggested by Paul Steinhardt and Neil Turok, tells a similar story. But, he says, their ideas come from string theory. And that, to Penrose, is a Bad Thing.
Penrose has no time for strings. 鈥淢y main objection is all those extra dimensions, which don鈥檛 make any sense,鈥� he says. Witten aside, says Penrose, string theorists are not facing up to their problems. 鈥淚 don鈥檛 see string theory converging on anything. In fact, it鈥檚 diverging: it has got wilder and wilder.鈥�
That鈥檚 part of the reason why, after Cycles of Time, he will publish Fashion, Faith and Fantasy in the New Physics, a critique of modern physics. String theory provides the 鈥渇ashion鈥�, but there are other targets too.
The 鈥渇aith鈥� is the idea that quantum mechanics is fundamental to the universe. Not that Penrose wants to take anything away from quantum theory. It is, he says, spectacularly successful in describing what happens on subatomic scales. But that doesn鈥檛 mean it鈥檚 the final answer to describing every aspect of reality. What鈥檚 more, he says, it has opened the floodgates for every flaky idea under the sun. 鈥淨uantum mechanics is so successful and so non-intuitive that people think they can have any old theory they like and it could be perfectly true,鈥� he says.
And the fantasy? Inflationary cosmology: the idea that, a few moments after the big bang the universe took just a fraction of a second to expand from the size of a pea to the size of the Milky Way.
Penrose is not cowed by the fact that inflation now sits slap bang in the middle of the cosmological mainstream.
Few people would dare to attack the three main arms of modern physics in one hefty swipe, but Penrose obviously enjoys his status as a maverick, and is flattered by criticism from his scientific colleagues. Theorist Frank Wilczek at the Massachusetts Institute of Technology called Road to Reality 鈥渄eeply flawed鈥�, saying that Penrose had sidestepped his responsibility to respond to his academic critics, go into details, or deal with experimental facts. 鈥淕alileo pulled this off brilliantly, but times were much simpler then,鈥� Wilczek said. Penrose鈥檚 response? 鈥淚 consider he paid me an enormous compliment by comparing me unfavourably with Galileo.鈥�
鈥淔ew would dare to attack the three arms of modern physics in one hefty swipe鈥�
New Galileo or not, few people could carry off Penrose鈥檚 coups with such aplomb and so little collateral damage: after decades in science and a number of significant contributions, Penrose has countless admirers and few enemies. Perhaps that is because it is impossible not to like him. He is, in his own words, an incurable optimist, someone who is as excited about seeing his 9-year-old son building Lego robots as he is about solving the puzzles of the universe. The smile rarely disappears from his face, even when he tells of receiving 鈥渁n awful lot of nutmail鈥�. With two more books on the way, that mailbag is certain to fill up again, but that won鈥檛 put him off. 鈥淪top? No, why would I do that?鈥� he says.
