Coulomb explosion

This is why non-neutral plasma schemes aren't a road to fusion: the densities that could be practically achieved are extremely low.

The only references I can find online seem to be for studying materials (e.g., https://www.scienceinschool.org/article/2024/explosive-imagi...) and for nano machining (e.g., https://www.nature.com/articles/srep11313), I wasn't able to find any commercial uses.

Yes, although it's a very specialised process. Femtosecond lasers are ubiquitous in semiconductor and thin-film electronics manufacturing, where the dross produced by conventional laser machining is unacceptable. Beyond that, cardiovascular stents are probably the most widespread example - they're made of extremely thin-walled tube that is highly prone to thermal distortion and they require very good edge quality. Femtosecond lasers are increasingly commonly used in the laser texturing of injection mold tools because of the higher surface quality.

You can search for 'femtosecond micromachining' for an idea of the applications where this is being used. Most of the applications are still in high margin markets (aerospace, medical, semiconductor), but there are starting to be consumer applications in particular in the display industry. For example, cutting gorilla glass cleanly is most often done with femtosecond lasers these days.

Popularity is increasing rapidly as the cost for femtosecond lasers has been coming down. Wile you are not going to find a press release from Apple saying that they are installing a particular manufacturing technology on their iphone line, the sales numbers speak for themselves: there is a sizable fraction of 1B/year in sales of femtosecond systems which are being used to build _something_

Here is the Nature paper that confirms the claim: https://www.nature.com/articles/nature.2015.16771

Fantastic!

Probably not sodium. It's too unreactive for that.

You've no doubt seen the sodium explosions, but what actually explodes is hydrogen, not sodium itself. If you run water+sodium reaction in an inert atmosphere, or simply weigh down a chunk of sodium so it quickly sinks to the bottom of the vessel, the result is much more tame.

On the other hand, starting with potassium, you probable start to get enough charge separation to tear apart solid chunks of metal.

I'm having trouble finding anything about this algorithm online, would you be able to link a review or one of those white papers you mentioned?

Would be nice to see some more concrete data/references. This is a big claim. I mean, if it is "basically the same" but "faster and requires fewer examples" you can just say that it's "strictly better" than K-means, and stop using K-means ever. However, everybody is aware of K-means and personally it's the first time I hear about "Columb exemplar algorithm".