Sonoluminescence has always been puzzling because different experimental setups—standard tabletop SL, NASA’s microgravity experiments, and the famous “dark‑bubble” regime studied by Putterman—behave so differently that they almost look like different phenomena. Until now, there has been no unified way to compare these regimes or understand how they relate to one another. This paper changes that. What we show is that all of these regimes—bright SL, dim SL, microgravity SL, and the dark‑bubble anomaly—actually live on the same underlying structure: an invariant manifold defined by the coupled Klein–Gordon and Rayleigh–Plesset dynamics. By mapping each experiment into this common coordinate system, we can finally compare them directly and see how they differ in a structural, rather than anecdotal, way. By placing all three regimes on the same invariant manifold and comparing them with the same solver, the same metrics, and the same nondimensional framework, this paper provides the first unified structural comparison of sonoluminescence regimes. It shows that the differences between NASA, SL, and Putterman are not mysterious or contradictory—they are geometric. They arise from where each regime sits on the manifold. This gives the field a new way to understand old results, reconcile conflicting observations, and reason about SL behavior in a principled, structural way.
David Mulnix (Sun,) studied this question.