Aliens? Not yet

I'm indebted to a post called 'Rogue Planets' by Ann Finkbeiner of The Last Word on Nothing back in February for much of the following.

This morning I read a review of a book called 'The Eerie Silence', by Paul Davies, just out in paperback here (Penguin), which apparently debates the evidence base (or rather lack of evidence) for the existence of aliens, and why, if they exist, they haven't been in touch.

I make a couple of breathtaking assumptions here.  The first is that these aliens will have evolved on roughly Earthlike planets, the second that they will have discovered, at about the same stage of their evolution, the use of the electromagnetic spectrum to transmit information, and fallen in love with this as deeply as we have over the last century or so.  So let's look at the planets.

According to state of the art astronomy, Kepler -10b, the nearest candidate so far, seems to be about 560 light years away. Let’s pretend that it’s Earthlike (which it isn’t) and formed about the same time as us (who knows). It’s reasonable to assume, then, that evolution would have progressed at roughly the same rate, if not in the same direction. If so, what we see of them, and they of us, would be rooted in the late Middle Ages.

That’s a best-case scenario. So why are these clowns wasting their time hunting for medieval alien TV channels?  And why doesn't any of the literature I've ever come across take this simple fact of elementary physics into consideration?  If they are out there (unless they've discovered a way of moving information, never mind themselves, faster than the speed of light), we probably have well over five hundred years to wait before we can expect to see even their equivalent of Marconi's first efforts.  And another hundred for The Alien X Factor.