garden/2025-05-20.md

• I like magnets -- some ideas:
  • magnetic computing
  • magnetic 3d printing
  • magnetic assists
    • In general magnetism seems like an amazing way to transfer momentum?
  • magnetic gears
    • As in the little devices I've built
• Today (actually yesterday) I saw a great video on the principle of least action and it blew my mind a bit. It also introduced me to diffraction grating effects -- which I had heard about but hadn't grokked/seen demonstrated.
  • The fact that angular momentum is quantized... wow. Also it introduced me to diffraction gratings, which I had heard of only in passing.
  • And angular momentum has the same unit as action: Joule-second.
  • This all made me think also of...
    • Could you use diffraction gratings at astronomic scales to see into the past? E.g. by making visible light from a star that has taken a longer (slower) path to get to us.
    • The effect that makes lights 'stretch out' in one direction in some mediums, like water (think of night lights reflected on a lake) or... the effect that is apparent in my chrome kitchen countertop that is quite something and I sometimes call the rainbow folding). I'm unsure if these are really related but something about the discussion about the paths that light can take made me think of it.
  • All in all I really enjoy thinking about physics as of late.
  • -> Action principles and Lagrangian are both interesting over at Wikipedia.