All except for (precisely) the heat equation, which is not time-reversible (there is a “loss of information” as time passes, very badly and roughly speaking).

All except for (precisely) the heat equation, which is not time-reversible (there is a “loss of information” as time passes, very badly and roughly speaking). See https://math.stackexchange.com/questions/628720/why-heat-equation-is-not-time-reversible-time-arrow-in-mathematics https://math.stackexchange.com/questions/628720/why-heat-equ...