The bubble cavitation experiment has been overhyped. First, the issue of emitted radiation when the bubble collapse. The late Julian Schwinger (co-winner of the Nobel Physics prize with Richard Feynman) concluded that a sudden change of the dielectric constant at a fixed point in space brings about the emission. Something to do with Maxwell’s equations with time-dependent dielectric constants. Second, whatever the pattern of ultrasound in the container, the average molecular speed is not that much greater than the speed of sound in the liquid. The speed of the walls of the collapsing bubble is not that greater than the speed of sound in said liquid. The compression inside the bubble is not that great since the vapor inside the bubble is of the same chemical composition as that of the liquid: all you get is in-situ condensation. If the wall of the bubble was made of steel and the vapor inside is hydrogen, then the hydrogen will heat up to very high temperatures.
Just those two? Schwinger and Feynman? !!
And what do you have against Tomonaga? Is it just because the Japanese have gone ahead and researched cold fusion? /sarc>
Cheers!