...the ET's we want to meet would have to have lifespans in the hundreds of thousands of years per individual to get close enough for us to notice them....assuming our knowledge is complete -- and it never is.
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.