Two German physicists are claiming to have devised an experiment in which Photons travel across a distance of up to one meter at a velocity greater than the speed of light. That seems to be an obvious violation of Einstein’s theory of special relativity. And breathless headlines across the internet are declaring that it’s true. For example: “Germans Break The Speed Of Light” , “Scientists break speed of light in lab test” … and my favorite, “Experts do the ‘impossible’ by breaking speed of light.” Apparently, “Expert”, “Scientist”, and “German” are all synonyms for “physicist”.
Just two problems buried beneath all the hype — the expert German scientists don’t seem to be describing a newly discovered effect, and the effect in question doesn’t violate relativity.
In fact, the effect has been known for decades, and even has a name — the “Hartman effect”:
Experiments done with “single photonsâ€, classical light waves, and microwaves all show this apparent superluminality. The origin of these paradoxical effects has been a mystery for decades.
And leading physicists believe that the particles involved don’t travel (pdf) in the classical sense at all:
If a wave packet takes no more time to cover distance
10d than it does to cover a distance d, we must either imbue the packet with the intelligence to increase its speed by just the right amount to cover the greater distance in the same time or consider the possibility that we are not dealing with a propagation phenomenon. We have taken the latter approach in recent work where we show that tunneling is a quasi-static process in which an input pulse, much longer than the barrier width, modulates the amplitude of a standing wave in the barrier. Standing waves do not go anywhere: they stand and wave, with all moving parts in the same time phase.
It pays to be skeptical when someone claims to invalidate one of the most tested — and validated — theories in history.
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