nLab stress-energy tensor




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In a model (in theoretical physics) of gravity coupled to other fields, the energy momentum tensor or stress energy tensor T is the variation of the matter part S fieldsS_{fields} in the Einstein-Hilbert action with respect to the metric, δS fields=Tδg\delta S_{fields} = T \delta g.

It is a measure for the energy and momentum density of the matter contribution to the theory.

Since the variation of the Einstein-Hilbert action S EHS_{EH} is the Einstein tensor GG, the equations of motion of gravity, hence Einstein's equations assert that (up to constant prefactors)

G=T. G = T \,.


Renormalization and Vacuum energy

The renormalization freedom in perturbative quantization of gravity (perturbative quantum gravity) induces freedom in the choice of vacuum expectation value of the stress-energy tensor and hence in the cosmological constant.

For details see there.


Last revised on February 9, 2018 at 12:02:24. See the history of this page for a list of all contributions to it.