Farscape S04E11 - Unrealized Reality

Crichton gets sucked into a wormhole while he is studying it, but instead of exiting the wormhole on the other end he becomes trapped with a mysterious man inside the wormhole. The man claims he is a relation of The Ancients who Crichton met before and gave him his wormhole technology. He demonstrates the consequences of wormhole travel to Crichton and forces him to confront the possibility that he may never be able to get home.