Why Does Collapsing a Bubble with a Sound Wave Produce Light?

Absolutely! Ozone is produced as a byproduct but I don't have any refrences at hand. More generally it can be said reactive oxygen species are produced as an intermediary that turn into several compounds as plasma is cooled.

Whatever gas you make bubbles from is going to be ionised(plasma is created during cavitation) and it's going to produce a cocktail of chemicals inside as it cools below ionisation temperature.

Many of these are shortlived eg oxygen reacts with hydrogen or nitrogen to form more stable compounds but some intermediaries can be stable and be detected.

The absolute max amount of nitric acid you can get for example is proportional to the amount of air dissolved in water. If you cavitate entire 1L of water max HNo3 you can get is about 20mg. Realistically it's not possible to cavitate such a large volume of water at once and there's a competition among reactants to form other products eg oxygen is going to used for hydrogen peroxide as well. Very sensitive instruments are used to detect these.

This is studied in sonochemistry —using bubbles to drive chemical reactions.Not enough for large scale production but small doses of chemicals — mostly radicals can be delivered by bubbles making it useful as a disinfectant.

Are you agreeing or disagreeing with it being trivial to check if theres fusion?

> However it's quite possible that I'm wrong. Because bubble science keeps on throwing new surprises.

Ultimately that's my assertion. No need for exaggerated/optimistic claims when something interesting turns up about it on a regular basis.

Unfortunately, no- while atoms fusing has a fixed mass to energy conversion... getting them close enough that they'll fuse takes a lot of energy. The three hurdles to effective fusion are: 1) getting more energy from fusion than was spent making it happen 2) extracting the extra energy 3) (this never gets covered) avoid neutron flux turning the whole thing into radioactive scrap before it can pay for itself and storage.

National ignition facility (NIF) recently got exited about more energy out than they put in. They don't have a plan for #2 or #3- but as a research facility focusing on #1 thats OK.

Numerous tokamak designs try to handle #1 and #2, but handle #3 by putting rails into the reactor for robots to replace and repair things.

I'm very pessimistic about #3- nothing is immune to neutron damage from fusion, it's just engineering it to fail in a way thats useful. And, once the public accepts the problem, produces less nuclear waste than fission.