Newman–Janis algorithm

The Newman–Janis algorithm is a method used in general relativity and theoretical physics for generating new solutions to the Einstein field equations. Specifically, it is often utilized to derive rotating black hole solutions from static ones. The algorithm is named after its developers, Eric Newman and Roger Penrose. The typical application of the algorithm involves starting with a known stationary solution (like the Schwarzschild solution for a non-rotating black hole) and transforming it to create a rotating solution (like the Kerr solution).