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The stress–energy tensor, sometimes called the stress–energy–momentum tensor or the energy–momentum tensor, is a tensor physical quantity that describes the density and flux of energy and momentum in spacetime, generalizing the stress tensor of Newtonian physics. It is an attribute of matter, radiation, and non-gravitational force fields.
If the energy–momentum tensor T μν is that of an electromagnetic field in free space, i.e. if the electromagnetic stress–energy tensor = (+) is used, then the Einstein field equations are called the Einstein–Maxwell equations (with cosmological constant Λ, taken to be zero in conventional relativity theory): + = (+).
The energy and momentum of an object measured in two inertial frames in energy–momentum space – the yellow frame measures E and p while the blue frame measures E ′ and p ′. The green arrow is the four-momentum P of an object with length proportional to its rest mass m 0.
The symmetry of the tensor is as for a general stress–energy tensor in general relativity. The trace of the energy–momentum tensor is a Lorentz scalar; the electromagnetic field (and in particular electromagnetic waves) has no Lorentz-invariant energy scale, so its energy
The stress–energy tensor of a relativistic pressureless fluid can be written in the simple form T μ ν = ρ 0 U μ U ν . {\displaystyle T^{\mu \nu }=\rho _{0}U^{\mu }U^{\nu }.} Here, the world lines of the dust particles are the integral curves of the four-velocity U μ {\displaystyle U^{\mu }} and the matter density in dust's rest frame is ...
Download as PDF; Printable version ... is an algebraic classification of rank two symmetric tensors. ... commonly applied to the energy–momentum tensor ...
The energy-momentum tensor is = () = ( () () ()) It can be shown that this energy momentum tensor is traceless, i.e. that = = If we take the trace of both sides of the Einstein Field Equations, we obtain = So the tracelessness of the energy momentum tensor implies that the curvature scalar in an electromagnetic field vanishes.
The Einstein tensor is a tensor of order 2 defined over pseudo-Riemannian manifolds.In index-free notation it is defined as =, where is the Ricci tensor, is the metric tensor and is the scalar curvature, which is computed as the trace of the Ricci tensor by = .