The electromagnetic field tensor F constructs the electromagnetic stress–energy tensor T by the equation: T α α β β = 1 μ μ 0 ( η η α α ν ν F ν ν γ γ F γ γ β β + 1 4 η η α α β β F γ γ ν ν F γ γ ν ν ) where η is the Minkowski metric tensor (with signature (+ − − −)). Notice that we use the fact that ε ε 0 μ μ 0 c 2 = 1 , which is predicted by Maxwell's equations.