## Stress tensor

Why stress tensor must be symmetric?

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 Recognitions: Science Advisor A nonsymmetric stress tensor means that there is an interior source of stress energy (Cauchy's second law of motion).
 Some reference for this perhaps? What that means physically? -Example!

## Stress tensor

The T00 component of the stress energy tensor is energy density, the T11, T22, T33 (the diagonal components) are momentum flows or pressures. The off diagonals represent shear stresses and as Andy has pointed out a non-symmetric tensor means there is an interior source of energy. In GR this tensor usually represents a perfect fluid which is either dust (zero pressures) or radiation which is a fluid with pressure but no shear stress.

Recognitions:
 I don't understand this. Is there some other way. If $$\hat{N}$$ is symmetric then $$\hat{N}=\hat{N}^*$$. Maybe from this?