[PvK]

Originally posted by geoschmo:
... Actually there's not much difference in this case. If is his basic assumtion is correct, that a new colony could send a new colony ship in 100 years, and additionally we assume that it takes an average of 100 years for the each colony ship to reach it's new home, we could colonize the entire galaxy in less then 4000 years.

Huh? Reversing your math, 4000 years, with 100 year stops at each system, and 100 years between systems, is 200 years per system expansion. 4000 / 200 = 20 systems wide, the galaxy. Sounds more like an SE4 quadrant than a galaxy, to me.

That's about the length of recorded human history. But even if he meant it would take 100,000 years, considering the age of the galaxy we should be seeing someone out there. So either we are alone, or they don't want us to know they are there, or it's a lot harder then we think to get around out there.
...

Or they aren't doing anything that we have been able to observe, not necessarily because they care if we know about it, or not. The EM broadcasts we scan for may be obsolete, muffled, or undiscovered for all other intelligent life that we are in the correct time/space position to observe.

PvK