Given a particle travelling very close to the speed of light encountering a barrier, is it possible for the particle to exceed the speed of light by tunnelling forward in the direction of motion through the barrier?
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Doesn't there need to be a barrier for a particle to tunnel? – Kyle Kanos Feb 09 '18 at 12:49
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@KyleKanos I've edited it to include mention of a barrier. – Josh Feb 09 '18 at 12:56
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If you have access to a library, the following article looks as it may be of interest to you: "Solid State Communications" Volume 82, Issue 11, June 1992, Pages 867-870, "Transit time for quantum tunnelling" by Mark J.Hagmann. If you search the web I think there was a flurry of interest in this subject at one time. – jim Feb 09 '18 at 17:25
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Here is the simple quantum mechanical barrier tunneling situation:
According to classical physics, a particle of energy E less than the height U0 of a barrier could not penetrate - the region inside the barrier is classically forbidden. But the wavefunction associated with a free particle must be continuous at the barrier and will show an exponential decay inside the barrier. The wavefunction must also be continuous on the far side of the barrier, so there is a finite probability that the particle will tunnel through the barrier.
etc.
The impotant thing to keep in mind is that the energy level is the same inside and outside the barrier, thus the particle must have the same momentum i.e. velocity all through. It is only the probabilities that change, because this is a quantum mechanical phenomenon.
A particle moving near the velocity of light and hitting a barrier, may radiate Cerenkov radiation entering the medium, and thus reduce its energy, but that is another story, not tunneling, itis scattering.
anna v
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