The prospect of time travel seems unlikely, according to the latest findings by physicists who confirmed the ultimate speed limit for photons, which are packets of light.
The universe's ultimate speed limit is the speed of light in vacuum. Recent experiments suggested that single photons might beat it and allow for the prospect of time travel, but now findings indicate that individual photos are also limited to the vacuum speed limit.
Einstein's theory of special relativity maintains that an event's effect cannot precede its cause by travelling faster than light. A violation of this causality would permit time travel.
The limit in vacuum is a fixed number - about 300,000km per second, but the speed of light can vary.
"By showing that single photons 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 photon," said Professor Shengwang Du of Hong Kong University of Science and Technology.
In conclusion, photons cannot time travel, and moving information around at faster-than-light speeds is not possible. But that doesn't mean that time travel is entirely ruled out.