OBSERVABILITY OF THE BULK CASIMIR EFFECT - CAN THE DYNAMICAL CASIMIR EFFECT BE RELEVANT TO SONOLUMINESCENCE

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.