Is the Casimir effect relevant to sonoluminescence?

TL;DR

This paper calculates the Casimir energy for dielectric spheres considering dispersion and finds it cannot explain sonoluminescence, as the energy is positive, decreases with radius, and is too small compared to emitted light.

Contribution

It provides a direct frequency summation calculation of Casimir energy for dielectric spheres, incorporating dispersion and zeta function regularization, and assesses its relevance to sonoluminescence.

Findings

Casimir energy for dielectric spheres is positive.

Casimir energy increases as sphere radius decreases.

Casimir energy is too small to account for sonoluminescent energy.

Abstract

The Casimir energy of a solid ball (or cavity in an infinite medium) is calculated by a direct frequency summation using the contour integration. The dispersion is taken into account, and the divergences are removed by making use of the zeta function technique. The Casimir energy of a dielectric ball (or cavity) turns out to be positive, it being increased when the radius of the ball decreases. The latter eliminates completely the possibility of explaining, via the Casimir effect, the sonoluminescence for bubbles in a liquid. Besides, the Casimir energy of the air bubbles in water proves to be immensely smaller than the amount of the energy emitted in a sonoluminescent flash. The dispersive effect is shown to be inessential for the final result.