I assume that interstellar travel is really difficult for any civilization. That assumption is based on my knowledge of physics (relativity in particular).
First you need an incredible amount of energy to get even a modest mass out of the earth's gravity well. Then you you need a truly fantastic amount of energy to get it up to a fraction of the speed of light. Then you need an equally fantastic amount of energy to slow it down again at it's destination. Then you run into time dilation effects, which diminish the usefulness to the sender of any information they are going to get back (due to the delay).
Going slowly has it's own issues. If it takes you 100,000 years to cross the space between 2 stars, you are going to need a lot of energy/food to keep your crew/robots/computers going - because there isn't going to be much solar energy available. Also is any civilization going to invest the effort to create a probe/mission that they are not going to hear back from over that sort of time-scale?
Very true, but the point is it just shows there's a lot we don't know still that an advanced civilization might and likely have already discovered and learned to harness/control.
