On stationary solutions to the vacuum Einstein field equations
arXiv:1606.00543
Abstract
We prove that any 4-dimensional geodesically complete spacetime with a timelike Killing field satisfying the vacuum Einstein field equation with nonnegative cosmological constant is flat. When dim , if the spacetime is assumed to be static additionally, we prove that its universal cover splits isometrically as a product of a Ricci flat Riemannian manifold and a real line.
24 pages