Observational entropy appreciation club

John von Neumann said: Look! Forget my von Neumann entropy, Eugene had this wonderful idea, observational entropy! It’s much better! He’ll tell you more about it.

Eugene Wigner went to study a hydrogen atom instead, for which he got the Nobel prize (the guy knew what he was doing).

Alfred Wehrl: hmm this is an obvious and cool quantity, we should study it… and he wrote about one page about it.

Now it’s our turn.