Scientists at the University of Queensland, Australia, successfully sent a photon, a single particle of light, back through a closed timelike curve and then observed the photon as it interacted with its older self.

"Time travel was simulated by using a second photon to play the part of the past incarnation of the time-travelling photon," said University of Queensland physics professor Tim Ralph.

The lead author of the paper, PhD student Martin Ringbauer, was quoted by The Week as saying, the experiment aimed to examine the intersection of quantum mechanics and Einstein's theory of relativity.

"The question of time travel features at the interface between two of our most successful yet incompatible physical theories," Ringbauer said. "Einstein's general relativity and quantum mechanics."

Einstein's theory of relativity suggests that it may be feasible to travel backwards in time by following a "space-time path" that doubles back and returns to its own starting point in space, but at an earlier time.