Heat equation by Ciro Santilli 34 Updated +Created
Besides being useful in engineering, it was very important historically from a "development of mathematics point of view", e.g. it was the initial motivation for the Fourier series.
Some interesting properties:
  • TODO confirm: for a fixed boundary condition that does not depend on time, the solutions always approaches one specific equilibrium function.
    This is in contrast notably with the wave equation, which can oscillate forever.
  • TODO: for a given point, can the temperature go down and then up, or is it always monotonic with time?
  • information propagates instantly to infinitely far. Again in contrast to the wave equation, where information propagates at wave speed.