just working my way through Susskind's "Theoretical Minimum". At the Langrangian formalism I'm in novel territory so this may be a dumb question. Kind of multiple choice or fill in a real answer. Why is there no term for the Entropy of a system in the Lagrangian? Is it because time is an independent background variable? Or is Entropy included in potential energy? Or is it because the Lagrangian is approximate (like Newton) or something? It's implied by "the principle of least action" wher the L is minimized in the action Or it gets added later, just keep reading Or am I missing it altogether?