Many of my science professors have remarked that the law of conservation of mass and energy is unprovable (or at least unproven); is this really the case, however? Isn't the problem of the conservation law precisely the problem of induction? (I.e., we observe that the mass and energy of every system we have ever examined has remained constant, but how do we know that this will hold true (1) in the future and (2) of all systems?) But presumably when my professors have said that the conservation law is unproven, they didn't mean that this is so because of the problem of induction (after all, if they took this route then all of science would be "unproven"!). I feel as though they are treating the conservation law as exceptional when in fact it is not.