. "Kerr vacuum solution" . . "Kerr spacetime" . "Kerr metric" . . "extremal Kerr" . "Kerr solution" . "Kerr metric" . . . . "Kerr Metric" . "spinning" . . . "flattened space-time" . . . . . "Kerr vacuum" . . "Kerr geometry" . . "rotating" . "Kerr black holes as wormholes" . . "Kerr black holes" . "Kerr black hole" . . . "uncharged, rotating black hole" . "the exact solution" . . "Kerr" . "Kerr-type" .