Wormholes travel?

I know that there was an expirement thinking that wormholes are time portals. They send a space craft (or something, can`t recall) into one and it showed -- 2004 (for example) at the entrance..... 2009 (ex) in the middle... and then 2004 at the exist so he returned. They said that wormholes have to be circular: () so there will be no exist but only entrance and middle. The only problem will be how to get back?... but is this true... anyway with scientific proof.