The Large Hadron Collider could - just possibly - be capable of causing matter to travel backwards in time.
"Our theory is a long shot, but it doesn't violate any laws of physics or experimental constraints," says Tom Weiler, a physics professor at Vanderbilt University.
One of the main goals of the LHC is to find the Higgs boson, or 'God particle', necessary to explain why particles like protons, neutrons and electrons have mass.
And some scientists predict that if the collider succeeds in producing the Higgs boson, it will create a second particle, called the Higgs singlet, at the same time.
But according to Weiler and colleague Chu Man Ho, these singlets should have the ability to jump into a fifth dimension where they can move either forward or backward in time, reappearing in the future or past.
"One of the attractive things about this approach to time travel is that it avoids all the big paradoxes," Weiler says.
"Because time travel is limited to these special particles, it is not possible for a man to travel back in time and murder one of his parents before he himself is born, for example. However, if scientists could control the production of Higgs singlets, they might be able to send messages to the past or future."
The pair say their theory is testable: if the LHC starts generating Higgs singlet particles and their decay products, it could mean that they were produced by particles traveling back in time to appear before the collisions that produced them.
Weiler and Ho's theory is based on M-theory, a 'theory of everything' which can accommodate the properties of all the known subatomic particles and forces - but which requires 10 or 11 dimensions instead of our familiar four.
Weiler began looking at time travel six years ago to explain anomalies that had been observed in several experiments with neutrinos. He and his colleagues came up with an explanation of the anomalies based on the existence of a hypothetical particle called the sterile neutrino, which should be capable of traveling through extra dimensions.
The team's ideas have been taken up by science fiction writers: Final Theory by Mark Alpert and Joe Haldeman's novel The Accidental Time Machine both involve time travel based on these theories.