  We start by surveying the history of the idea of a fundamental conservation
law and briefly examine the role conservation laws play in different classical
contexts. In such contexts we find conservation laws to be useful, but often
not essential. Next we consider the quantum setting, where the conceptual
problems of the standard formalism obstruct a rigorous analysis of the issue.
We then analyze the fate of energy conservation within the various viable paths
to address such conceptual problems; in all cases we find no satisfactory way
to define a (useful) notion of energy that is generically conserved. Finally,
we focus on the implications of this for the semiclassical gravity program and
conclude that Einstein's equations cannot be said to always hold.
