Quantum inequalities

Quantum inequalities are a concept in quantum field theory, particularly related to the study of the energy conditions in curved spacetime. They provide constraints on the local energy density allowed by quantum fields, especially in the context of quantum fluctuations in vacuum states. In classical general relativity, the energy conditions (such as the weak energy condition, the strong energy condition, etc.) define certain properties that energy-momentum tensors must satisfy to ensure physically reasonable conditions, such as avoiding certain types of singularities or pathological behaviors.