🚀 go-pugleaf

In article <1993Jan6.074948.27304@murdoch.acc.Virginia.EDU>, crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:
|> 
|>      Just curious.  What meaning is assigned to 'the dynamical analogue
|>      of the Casimir effect'?  I don't really see any place for the 
|>      Casimir effect or an analogue in the process.  This isn't exactly
|>      a subtle indication of zero-point energy.  Are you sure it
|>      wasn't a joke?  
|> 

Definitely not a joke: Proceedings of the National Academy 89(4091)1992.

The basic idea, as best I understand it, seems to be this. The ordinary
Casimir effect concerns two static conductors. One calculates the energy
difference due to the vacuum energy which exists between them; this leads
to an inverse-fourth-power force. Now consider the case where the conductors
are in motion. The time dependence introduces a new level of complexity.
In ordinary perturbation theory, one difference between the static and
time-dependent cases is that in the static case you calculate changes in
energy levels, while in time-dependent theory you calculate transition 
probabilities; the same is true here. In the dynamic case, there is a
probability for a photon to be emitted -- hence, possibly, sonoluminescence.

Actually reading the paper indicates that this is not quite, as I had
thought, a theory of sonoluminescence already completed; no experimental
data is addressed. However, he states repeatedly that this is his mechanism
and that he in fact developed the theory with sonoluminescence in mind.

Also with cold fusion in mind, by the way, though he doesn't say so. The
reason I knew about this was that he gave a talk here last year on both
subjects, although he deliberately did not make any explicit link between
them: he just said that sonoluminescence proves that everyday phenomena
(bubbles on propellors, electrochemical cells) may hold unexpected new
physics.

Incidentally, I can think of a "hand-waving" reason for at once thinking
that the Casimir effect might be involved. Although everyone thinks of the 
static Casimir effect as "a subtle indication of zero-point energy", it's
really not so subtle when you think about it: at a certain scale of distances,
namely the scale of small water droplets, it's van der Waals and Casimir
rather than Newton and Maxwell you have turn to. Now sonoluminescence
originates with bubbles right in that size regime, but in a dynamic
environment... If only I could think of things like this in advance, I'd
be Schwinger!

N. Redington