Reply #16: All other factors aside, our radio waves really haven't traveled that far

[htuttle]

100 or 200 LY sounds like a long distance, but considering that even just the disk of the Milky Way is over 1000 LY thick out where we are, our radio waves haven't even traveled half of the thickness of the galactic disk yet. Our EM radiation hasn't even left our backyard yet relatively speaking (nor could we pick up EM radiation unless it was nearly next door).

Regarding alien civilizations traveling here -- I highly doubt it unless they've found a way to travel FTL, which might not even be possible (in fact, all of our current mainstream physics says it probably isn't). Using our fastest spacecraft (the Deep Space One probe), I think it would take over 15,000 years just to get to Alpha Centauri (one way). Considering that would encompass the entire span of known human history, much less the return trip, I'm not entirely surprised nobody has shown up on our doorstep yet.