 Stress–energy tensor

The stress-energy tensor describes local energy density, momentum density, and stress. Compatibility with the Einstein field equations requires covariant conservation ${\nabla }^{\mu }{T}_{\mu \nu }=0$.

The stress-energy tensor is a fundamental concept in physics, particularly in the fields of relativity and continuum mechanics. It is a mathematical object that describes the distribution of energy, momentum, stress, and pressure within a physical system.