I ws researching this very subject once... one of those selfsame authors had also said, when they first had been calculating planets by observing a star's ever-so-slight wobble, caused by a planet, that they would not likely find any terrestrial planets, like Earth, Mars, and Venus, as they are usually too small to cause that wobble. The giant gas planets are the only ones that have that kind of gravitational authority, and again, its on such a small scale.
I believe the had said that for now, they could check out those systems that had the gas giant, in hopes of looking closer at them to see if they saw more abberations, whcih could entail smaller, non-visible terrestrial planets.
Dont give up hope, hell, they cant even see these gas giants hardly at all. Besides, Hawking had to renig (is this a proper word?) on his bet with what's-his-name about black holes. I think he has to buy his an encyclopedia set now, or something. I think that the bet was something about whether or not the black hole leaks only x-rays (at its poles only). I believe Hawkingfound they will reach a critical mass after a point, or something. Its damned fun reading, thats for sure.
I figure the Lord did make other flocks, maybe they are really far out there.... they are probrobly unique too. There was a lot of stars that have already burnt out, Generation 0 an Generation 1 stars are laready gone... our universe is kinda middle-aged now, I bet you someone else already evolved a long time ago and moved off or something... who knows?
Its illogical to have all this universe, and beyond, which will be provable soon enough, only for little old us. I bet He just orchestrated this just right so we dont meet up until we're a little more stable and chilled out. I just hope whoever is out there is so awesomely different than we could imagine, so we'd have that much more to share. Of course, froma third-person perspective, humans are pretty neat unto ourselves, just look at the fairer sex
.