I used to think the following: Either time travel is never going to be possible, or the world will end before it becomes possible. How did I come to such a depressing conclusion? Simple. We haven't been visited by people from the future. Ergo, what I said before. If time travel ever becomes possible, we'd have been visited.
But now I see the flaw in my logic. There's another possibility: Perhaps time travelers from the future are just really sneaky. If so, and they've been here in our time, how would we know? So maybe they're all around us and are just not letting us in on the secret, not out of meanness, but because they don't want to destroy their own present by introducing the dreaded time travel paradox.
That's the problem caused when you go back in time to kill your grandfather, only to discover this means you were never born. Oh well. Maybe the instruction manual on the time machine makes this clear: Do not, under any circumstances whatsoever, interact with the old-timers, or you'll screw up everything here!
Well, it turns out that math has come to the rescue, as it usually does:
Parallel universes really do exist, according to a mathematical discovery by Oxford scientists that sweeps away one of the key objections to the mind boggling and controversial idea.
The work has wider implications since the idea of parallel universes sidesteps one of the key problems with time travel. Every since it was given serious lab cred in 1949 by the great logician Kurt Godel, many eminent physicists have argued against time travel because it undermines ideas of cause and effect to create paradoxes: a time traveler could go back to kill his grandfather so that he is never born in the first place.
But the existence of parallel worlds offers a way around these troublesome paradoxes, according to David Deutsch of Oxford University, a highly respected proponent of quantum theory, the deeply mathematical, successful and baffling theory of the atomic world.
He argues that time travel shifts between different branches of reality, basing his claim on parallel universes, the so-called "many-worlds" formulation of quantum theory.
The new work bolsters his claim that quantum theory does not forbid time travel. "It does sidestep it. You go into another universe," he said yesterday, though he admits that there is still a way to go to find schemes to manipulate space and time in a way that makes time hops possible.
If you do kill dear old granddad, no worries, mate. You won't disappear like Michael J. Fox in
Back to the Future. You'll just cause a fork in the road, as it were, whereby the new branch of the universe where you aren't born (because you killed your grandfather, you idiot) goes off on its merry way, while the old one where you
were born, unfortunately goes on.
So time travel could well be possible. And it may be coming sooner than you think:
The first time travelers from the future could materialize on Earth within a few weeks.
Physicists around the world are excitedly awaiting the start up of the £4.65 billion Large Hadron Collider, LHC - the most powerful atom-smasher ever built - which is supposed to shed new light on the particles and forces at work in the cosmos and reproduce conditions that date to near the Big Bang of creation.
Prof Irina Aref'eva and Dr Igor Volovich, mathematical physicists at the Steklov Mathematical Institute in Moscow believe that the vast experiment at CERN, the European particle physics centre near Geneva in Switzerland, may turn out to be the world's first time machine, reports New Scientist.
The debut in early summer could provide a landmark because travelling into the past is only possible - if it is possible at all - as far back as the point of creation of the first time machine.
That means 2008 could become "Year Zero" for temporal travel, they argue.
Time travel was born when Albert Einstein's colleague, Kurt Gödel, used Einstein's theory of relativity to show that travel into the past was possible.
Ever since he unveiled this idea in 1949, eminent physicists have argued against time travel because it undermines ideas of cause and effect to create paradoxes: a time traveler could go back to kill his grandfather so that he is never born in the first place.
But, sixty years later, there is still no fundamental reason why time travellers cannot put historians out of business.
But the Russians argue that when the energies of the LHC are concentrated into a subatomic particle - a trillionth the size of a mosquito - they can do strange things to the fabric of the universe, which is a blend of space and time that scientists called spacetime.
While Earth's gravity produces gentle distortions in spacetime the LHC energy can distort time so much that it loops back on itself. These loops are known to physicists as "closed timelike curves" and they ought, at least in theory, to allow us to revisit some past moment.
So keep your eyes peeled and your ears to the ground.
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