About Time

The possibility of being able to travel, at will, back and forth through time has continued to fascinate us since, and even before then: Wells was pre-empted, in 1889, by Mark Twain with his A Connecticut Yankee in the Court of King Arthur. Recent years have seen Hollywood toying with the clock, not only with adaptations of the Wells tale, but with the popular Back To the Future series, an adaptation of Michael Crichton's Timeline and the darkly disturbing Butterfly Effect. Across the airwaves, quite apart from the temporally anarchic Doctor Who, just last weekend BBC Radio 3 broadcast an accomplished adaptation of Wells's original, while yesterday saw BBC Radio 7 embark on a time-travel comedy serial, The Sofa of Time.

All of us at some point must have wished we could circumvent the inexorable, one-way strictures of time, either to rewrite less than glorious episodes in our lives, or on a grander canvas circumvent global tragedy by assassinating Hitler, or preventing the assassination of Archduke Franz Ferdinand, or simply go on safari in the Jurassic age.

Fantasy, of course: but time travel, once dismissed as pulp fiction by serious scientists, has become "something of a cottage industry in the theoretical physics community", according to Professor Paul Davies, physicist, astrobiologist and award-winning science writer, who a few years ago published a book with the engagingly no-nonsense title of How To Build A Time Machine. In it, Davies makes it clear that travelling into the future is entirely allowable, according to Einsteinian laws of physics. And, while the speed of light is an unbreachable barrier, according to conventional or "classical" physics, even at a mere 99.999999 per cent of the speed of light you could not only reach the far side of our galaxy within a human lifetime but also start to warp time.

Coming back, however, is a different matter. It is one for which Davies and others have speculated on the possibility of harnessing the power of "wormholes". Remember those fearsome tunnels through time and space down which Jodie Foster hurtled in the film Contact? That was Hollywood's vision, but the concept of wormholes – originally called "Einstein-Rosen bridges" – has been speculated on since the 1930s, as tunnel-like shortcuts through space and time, because the unimaginably powerful gravitational forces within them could be harnessed to warp the space-time continuum.

However, Davies concluded that to build and operate a machine powerful enough to conveniently unravel space and time would require "the resources of a supercivilisation". So say goodbye to that glittering crystal-and-brass Wellsian machine you envisaged knocking together in your basement.

Since he wrote that, says Davies (London-born but currently based at Arizona State University, where he is director of Beyond, the university's Centre for Fundamental Concepts in Science), everything in his book still stands, but a recent development that could just feasibly bring the concept of time travel a little closer to reality is the Large Hadron Collider (LHC). This, the world's largest and most powerful particle accelerator, was built at Geneva by the European Organisation for Nuclear Research (CERN) to test high-energy physics hypotheses.

It has been speculated that the LHC, once it starts functioning properly, could possibly form Einstein-Rosen bridges. "There is a ghost of a chance, but no more than that in my opinion, that it could create microscopic wormholes," says Davies. Such thinking involves what he describes as "rather speculative, non-standard theories of gravitation. If we go with Einstein's General Theory of Relativity (which attributes gravity to the curving of space and time), which is what most of the discussion in my book was based on, then it's not going to happen. But in recent years there has been increasing attention given to alternatives to Einstein's theory, and one of those involves additional dimensions of space."

If some of these theories are correct, says Davies, we may just see a wormhole, on a microscopic level, created under laboratory conditions by the LHC, making the whole subject of time-travel that bit more credible. "The weakest point in the entire chain of reasoning is whether wormholes actually exist. But if the Large Hadron Collider really can make a wormhole, that would transform the whole landscape of the subject. Suddenly (it] would move from theory into the domain of experimentation."

Much of the research pertaining to this ever-intriguing topic takes us out of the relatively solid world of classical physics and Einsteinian theory and into the realms of quantum mechanics, with scientists questing after the "holy grail" of 21st-century physics, an overall theory of quantum gravity, which would supersede Einstein's and be applied to everything in the cosmos. Among those working towards this are Dr Charles Wang, reader in physics at the University of Aberdeen. "If we have a breakthrough in quantum gravity, then time travel would stand a better chance. We certainly expect some interesting result to come out soon – although we can't really promise a time machine," he laughs.

In the realm of quantum physics, says Wang, things tend to operate at miniscule sub-atomic levels, measurable only by the Planck scale, but recent advances in nanotechnology have enabled scientists to speculate on unprecedentedly large quantum objects.

At the miniscule scales of length and time described by quantum physics, at the level of what has been described as "spacetime foam", the laws of quantum mechanics allow for certain fluctuations in time.

"The main problem," says Wang, "is how to amplify this effect, and recent nanotechnology has enabled the control of larger quantum objects. Ultimately, of course, you'd want objects of human-being size to behave like quantum objects. In that case, the quantum fluctuations could defy certain limitations set by classical physics and you may experience larger fluctuations in time."

This, of course, is all theoretical. However, Wang adds, the nanotechnology and quantum-engineering developments mean that real progress is being made. "If this progress continues, then large quantum effects may have important implications for large time fluctuations. You may have a simplified forward or backward movement in time."

Ask him if he sees time travel ever being a practicality, outwith the realms of science fiction, and he is circumspect. "I'm not saying a time machine could ever be built any time soon, but there is encouraging progress being made towards evidence that might touch on this intriguing subject. At the moment you could certainly, in principle, send someone into the future, according to Einstein's laws. But it would be a one-way ticket."

Which leaves us to continue chewing over such speculative time-travel paradoxes as Michael J Fox interfering, almost terminally, with his parents' love life in Back To The Future, or, in Ray Bradbury's classic tale, A Sound of Thunder, the time-roving dinosaur-hunter who treads on a butterfly, thereby creating mayhem with the future from which he has come.

The classic paradox, of course, is what happens if you were to travel back and murder your parents before you're born: how could you be there to kill them in the first place?

The renowned cosmic physicist and author Professor Stephen Hawking has blown hot and cold over time travel in the past, but finally concluded it did seem a possibility. Although even he tempered his theorising by wondering why, then, we haven't been overrun by droves of "time tourists", anxious to view our quaint ways. Perhaps, one is tempted to suggest, they've had a discreet peek and decided to leave well alone.

If indeed time-travel does, er, materialise, it will be a brave man who first steps into the machine and presses that fast-forward button.

"I think you'd want to send the cat first," as Paul Davies has said.

And if you still think that all of this sounds improbable, to say the least, it's worth considering the remark, quoted in Davies's book, by JBS Haldane, the influential Scots evolutionary biologist and geneticist: "The universe is not only queerer than we think, it is queerer than we can think."

TRAVELLING FARE

The Time Machine (1895)

HG WELLS'S classic tale of a Victorian inventor who builds a time machine and ventures into the future, discovering that humanity has evolved into two distinct species, the pampered and vulnerable Eloi, and the troglodyte Morlocks who prey on them.

A Sound of Thunder (1952)

FAMOUS short story by Ray Bradbury (execrably filmed a few years ago by Peter Hyams), about a big-game hunter who journeys back to the Cretaceous age to shoot a dinosaur but, in classic time-travel paradox, steps on a butterfly, disastrously altering the future from which he has come.

Doctor Who (1963-)

IN what is now the longest-running TV sci-fi series in the world, William Hartnell, the first of (at least) 11 temporally freewheeling Doctors so far (with Matt Smith due to take up the sonic screwdriver next year), first stepped out of the policebox known as the Tardis back in 1963.

Back To The Future (1985)

POPULAR sci-fi movie, the first of a trilogy, in which Michael J Fox takes a short, sharp ride back to 1955 in a time-travelling DeLorean Special with eccentric inventor Christopher Lloyd. Avoids potentially disastrous affair with his mother and seals his future by getting his parents back together.

Life On Mars (2006-7)

DIDN'T go any further than back to the 1970s, but this series about Manchester Detective Chief Inspector Sam Tyler (John Simm) who is hit by a car and propelled back to a politically-incorrect 1973, proved hugely popular. Followed up last year by Ashes To Ashes, in which Keeley Hawes played a London police detective similarly transported back to the 1980s, there to meet Life On Mars's unreconstructed alpha-male character, Gene Hunt, a decade on.

The Time Traveller's Wife (2003)

AUDREY Niffenegger's unconventional romance novel, about a man with a genetic disorder that causes him to time-jump at inconvenient moments, became a bestseller, with a bit of help from Richard & Judy's Book Club.