Seth Shostak is an astronomer, specifically a radio astronomer. That is, he looks at radio signals coming from space from various cosmic objects. But a while back, he decided to change his focus (haha, get it?) somewhat. He doesn’t look for black holes and galaxies anymore. He looks for aliens.
Still, the folks at SETI been searching a while and haven’t heard anything. That doesn’t slow Seth down, though, because he knows that our technology is increasing rapidly. We’re getting so good at this, in fact, that Seth thinks we may hear from our cosmic brethren in the next 20 years or so!
But you know what? I’ll let him tell you all about it, in this TEDxSanJose talk he gave in April 2012. I think you’ll quite enjoy it. I think Seth makes a compelling case. And we’ll know soon enough. The galaxy is big. But we know there are billions of planets out there, some of them quite old…and we are getting better at this. If E.T. is out there, I hope SETI can find it.