Time Travel Is Impossible, Scientists Say

Jul 25, 2011, 16:41 by Sarah Long

Physicists proved even a single photon must obey Einstein's theory that nothing can travel faster than the speed of light, possibly debunking the idea of time travel once and for all.

A Hong Kong University of Science and Technology research team led by Du Shengwang said they had proved that a single photon, or unit of light, "obeys the traffic law of the universe," Fox News reports.

"Einstein claimed that the speed of light was the traffic law of the universe or in simple language, nothing can travel faster than light," the university said on its website, as reported by Fox News.

"Professor Du's study demonstrates that a single photon, the fundamental quanta of light, also obeys the traffic law of the universe just like classical EM (electromagnetic) waves."

Du, a professor at the University, added that the study improves understanding of how photons move.

"The results add to our understanding of how a single photon moves. They also confirm the upper bound on how fast information travels with light," he says, as reported by the Daily Mail.

"By showing that single protons cannot travel faster than the speed of light, our results bring a closure to the debate on the true speed of information carried by a single proton."

The possibility of time travel was raised 10 years ago when scientists discovered superluminal -- or faster-than-light -- propagation of optical pulses in some specific medium, the team said.

Scientists later realized it was only a visual effect, where the superluminal "group" velocity of many protons could not be used for transmitting any real information, according to the Daily Mail. 

The team's study was published in the U.S. peer-reviewed scientific journal "Physical Review Letters."