Ka. Milton et Yj. Ng, OBSERVABILITY OF THE BULK CASIMIR EFFECT - CAN THE DYNAMICAL CASIMIR EFFECT BE RELEVANT TO SONOLUMINESCENCE, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 57(5), 1998, pp. 5504-5510
The experimental observation of intense light emission by acoustically
driven, periodically collapsing bubbles of air in water (sonoluminesc
ence) has yet to receive an adequate explanation. One of the most intr
iguing ideas is that the conversion of acoustic energy into photons oc
curs quantum mechanically, through a dynamical version of the Casimir
effect. We have argued elsewhere that in the adiabatic approximation,
which should be reliable here, Casimir or zero-point energies cannot p
ossibly be large enough to be relevant. (About 10 MeV of energy is rel
eased per collapse.) However, there are sufficient subtleties involved
that others have come to opposite conclusions. In particular, it has
been suggested that bulk energy, that is, simply the naive sum of 1/2
(h) over bar omega, which is proportional to the volume, could be rele
vant. We show that this cannot be the case, based on general principle
s as well as specific calculations. In the process rye further illumin
ate some of the divergence difficulties that plague Casimir calculatio
ns, with an example relevant to the bag model of hadrons.