[math-fun] Reversible computation

This idea has been around since I first encountered computers --- maybe not as exotic as "quantum compution", but appears to this casual sceptic a good deal more soundly based. Wot, me worry? I fully expect to be pushing up daisies long before either notion becomes at all practicable! Mind you, I once said the same about climate change ... https://spectrum.ieee.org/computing/hardware/the-future-of-computing-depends... WFL