[Lonesome in Massachussets]

We could communicate with distant civilizations via radio. Low data rates and long message delay times, no doubt. The Milky Way, our “hood” is 100,000 light years across. If we try to communicate with a relatively nearby civilization, say 1000 light years distant, we could send a message today and would not expect a reply until 4013, or about the time between the present and the birth of Christ.

Of course, if you could travel near the speed of light, you could travel to this distant civilization in what for you would seem like a relatively (no pun intended) short time, but by the time you get back, the earth will be 2000 years older, and your mission will be the stuff of ancient legend, no one expecting to ever see you again.

[central_va]

The Fermi paradox can be asked in two ways. The first is, "Why are no aliens or their artifacts physically here?" If interstellar travel is possible, even the "slow" kind nearly within the reach of Earth technology, then it would only take from 5 million to 50 million years to colonize the galaxy.[15] This is a relatively small amount of time on a geological scale, let alone a cosmological one. Since there are many stars older than the Sun, or since intelligent life might have evolved earlier elsewhere, the question then becomes why the galaxy has not been colonized already. Even if colonization is impractical or undesirable to all alien civilizations, large-scale exploration of the galaxy is still possible; the means of exploration and theoretical probes involved are discussed extensively below. However, no signs of either colonization or exploration have been generally acknowledged.