Reversible computing should be mentioned, as it could be the holy grail of low energy use.
https://spectrum.ieee.org/computing/hardware/the-future-of-c...
https://spectrum.ieee.org/computing/hardware/the-future-of-c...
Glad that it's still moving, sad that it's at an even slower pace than the "functional/immutable will save the parallellization worries" stuff I encountered in the same period.