What I saw on the web on 2023.3.21

1. Vienna Concert
   by Keith Jarrett
   https://www.youtube.com/watch?v=hWf7WaU9oIo
   this. this is it.
   via memory
   
   
2. An aperiodic monotile
   by David Smith, Joseph Samuel Myers, Craig S. Kaplan, and Chaim Goodman-Strauss
   https://cs.uwaterloo.ca/~csk/hat/
   all hail the einstein!
   via several places. this is big news