Question

Is a self-wormhole possible?

Answer 1

Yo! Here's your answer! If we think of a wormhole as two blackholes where points on each horizon are identified. Should a "self-wormhole" not also be possible?                         E.g-Where opposite points on the event horizon are identified?  So, if you go in one side you emerge on the other side instantaneously.  (Not that this is how  wormholes work).  Well,instead of the topology being like a tube it would be like a cross-cap.   I can't see any reason why this shouldn't also be a solution of Einstein's equations. Hope that this helps you. (Btw,the concept of wormhole is just a theory.But,i like your thinking! :D) -TGA.