Re: Can sound waves tunnel through a vacuum?

RolandRB wrote:
>Can sound waves tunnel through a vacuum?

I though up a few ways that might make it look like they do:

If sound waves are incident on a membrane, which is closely placed to a
second membrane (separated by vacuum), then the waggling of one
membrane could cause waggling of the second membrane, which would then
setup sound waves on the far side. This could happen via Casimir
forces, gravitational forces, or (if the membranes were charged)
electrostatic forces. This may be considered cheating as these could be
considered as transduced forms, rather than sound itself, but it's a
thought.

Sound in air is not quantized (AFAIK) due to velocity not being
quantized, even phonons in solids are not really quantized, though
there are similarities. Phonons are properties of the material they are
in, not properties of the vacuum like EM is, so cannot of themselves
tunnel via vacuum.

The "wavefunction" of a phonon is determined by the positions of all
the atoms supporting it. This phonon wavefunction tails across the
vacuum to the same extent as the wavefunctions of the atoms in the
material tail across the vacuum. I guess that counts as bona fide
tunnelling, but you won't get much!

br

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