Better shelve that plan for a timehopping cultural tour of Renaissance Venice; physicists from the University of Hong Kong are convinced they’ve shown time travel to be impossible.
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. It was later found to be a visual effect, but researchers thought it might still be possible for a single photon to exceed light speed. Du, however, believed Einstein was right and determined to end the debate by measuring the ultimate speed of a single photon, which had not been done before.
“The study, which showed that single photons also obey the speed limit c, confirms Einstein’s causality; that is, an effect cannot occur before its cause,” the university said.
I’ll give it a maximum of two years before someone has a counter-theory that makes it possible once again…