Two U.S. physicists say if their theory is right, the Large Hadron Collider, the world largest atom smasher, could be the world's first time machine.

Vanderbilt University researchers Tom Weiler and Chui Man Ho say the machine could be capable of causing matter to travel backward in time, a university release said Tuesday.

"Our theory is a long shot," Weiler said, "but it doesn't violate any laws of physics or experimental constraints."

One of the major goals of the collider is to discover the elusive Higgs boson, the particle that physics theories invoke to explain why particles like protons, neutrons and electrons have mass.

If the collider succeeds in producing the Higgs boson, some scientists predict it will create a second particle, called the Higgs singlet, at the same time.

Weiler and Ho's theory says these singlets should have the ability to jump into an extra, fifth dimension where they can move either forward or backward in time and reappear 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 said. "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," he said.

The test of the researchers' theory will be whether the physicists monitoring the collider begin seeing Higgs singlet particles and their decay products spontaneously appearing in the collider. If they do, Weiler and Ho say they believe it will mean they have been produced by particles that travel back in time to appear before the collisions that produced them.