Equation Icon  R μν = R¯μν + 2 π(1 − α)((n μn )(nνn ) − (nμn )(nνn )) δ , αβμ μ αβ μ α β β α Σ R ν = R¯ ν + 2π(1 − α)(n n ν)δΣ, R = R¯ + 4π(1 − α )δΣ , (55 )