Hong Kong scientists show time travel is impossible
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Hong Kong physicists say they have proved that a single photon obeys Einstein’s theory that nothing can travel faster than the speed of light — demonstrating that outside science fiction, time travel is impossible.
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The 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.”
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“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.
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“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.”
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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.
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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.
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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.
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“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.
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“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 Du, assistant professor of physics.
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“Our findings will also likely have potential applications by giving scientists a better picture on the transmission of quantum information.”
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The team’s study was published in the U.S. peer-reviewed scientific journal Physical Review Letters.
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