Very true, there may be ways to move we don't know about yet, hell we're still unable to describe or see 2/3 of the material that makes up the universe!
So as we currently understand the nature of time and space and life the likely hood of 2 intelligent civilizations from different worlds coming into contact is virtually impossible.
"But I am not really willing to accept your premise, because it may well be that the means of communications they have are of a kind that we do not know how to receive, and that they would not have the means of communicating with sufficiently powerful radio or optical signals. That is something which, technologically, is too difficult for them but they would have some other means we would not recognize." -- Thomas J. Gold, 'Communication with Extraterrestial Intelligence' (Sagan, ed)