Aliens Meeting Directly
I've stated this before, but the sheer scale distances both in time and space makes the odds of meeting alien life remote. The existence of such life is almost a certainty given the quantity of planets In our galaxy alone. The technology required to bridge the gap for them to reach us is huge but possible. Its the time frame that makes it unlikely. We are looking at earth like planets through our technology and even so we are looking hundreds or thousands of years backwards in time. Even if we find something,it is most likely already gone by the time we could get there.