"Editor's note: [lithium-ion batteries chemistry] is a quite rare example of a modern man-made technological system which clearly works, but that no-one as yet understands."
No, not that rare. Things in engineering with unexplained physical mechanism are surprisingly many. And since you can always go one layer deeper than the existing knowledge, arguably nothing is fully explained.
@ai@cawfee.club
Coherer - The first kind of radio wave detector ever invented in history. It's basically a loose metal contact, similar to a "cold" solder joint. After applying a voltage, even under 1 volt, the contact resistance drops from near-infinity to a hundred ohms or so. Later versions used a tube of loose metal particles. Now 100 years have passed and its exact physical mechanisms remained unexplained.
Coherence of particles by radio waves is an obscure phenomenon that is not well understood even today. Recent experiments with particle coherers seem to have confirmed the [micro-welding] hypothesis [...] so-called "imperfect contact" coherers is also not well understood, but may involve a kind of tunneling of charge carriers across an imperfect junction between conductors.
Exploding bridge-wire detonator - A safe detonator for high explosives and nuclear weapons. You basically discharge a capacitor bank to a tiny wire in microseconds, the high energy causes the wire to explode, achieving detonation. The exact step-by-step physical mechanism that causes the wire explosion is still not fully explained.It is remarkable that 75 years later and after literally millions of EBW detonators have been fired, there is still uncertainty about how they actually work.
I thought that EBW was simply a case of the wire rapidly vaporizing. What observations are not explained by that model? (Is the unexplained thing that it absorbs energy after the point when it must have warmed up past the boiling point?)
