Abstract
In classical general relativity, many key results are proved under the assumption that matter obeys one of the classical energy conditions (dominant, weak, strong, etc). However, it is impossible for any quantum field to obey these conditions! In this talk I will describe the construction of the stress-energy tensor in curved spacetime, give a simple argument to show that QFT necessarily violates the energy conditions, and then discuss Quantum Energy Inequalities, the remnant of the classical energy conditions after quantisation.