It might also depend on how you are defining the word Universe. Multiple universes might exist in terms of time travel. If I hop in a time machine, and set it for yesterday, I will leave this universe and enter into a parallel universe. This means that anything I do in the parallel universe affects this universe in no way. I could theoretically kill my own father, or assassinate a world leader, then come back to this universe with nothing being changed.<br /><br />Now if you're talking about another physical universe, it could very well be possible that other universes exist. Can we travel to them in any way? Who knows, I would say it's not impossible, just very improbable.<br /><br />Unless you take some of Stephen Hawking's theories into consideration. If blackholes are the entrances to wormholes, then it is possible to either jump to another point in this universe instantaneously, or jump to another universe all together. <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>