Homogeneous Lorentz manifolds with simple isometry group (Q5948422)

The paper systematically discusses homogeneous Lorentz manifolds \(G/H\) with a simple isometry group \(G\). The main result reads: If \(H\) is a Lie subgroup of \(G=SO(2,n)\), \(n\geq 3\), such that the closure of \(H\) is noncompact and \(G/H\) admits an invariant Lorentz metric then the identity component of \(H\) is conjugate to the identity component of \(SO(1,n)\) in \(SO(2,n)\). If here, alternatively, \(G=SO(1,n)\) then the identity component of \(H\) is conjugate to the identity component of \(SO(1,n-1)\).