Hanson on Fermi

I've posted at great length on the Fermi Paradox — the simple question "Where are they?" in regard to extraterrestrial civilizations. One element of that paradox is simply that the time it would take for an expanding civilization to spread across the Galaxy is relatively short in geological terms. Or so we assume.

Now Robin Hanson has actually tackled the question in a pair of posts on his own blog, analyzing how long it would take for civilizations to bump into each other. It's not an easy read — the math is pretty rigorous, and Hanson uses graphics to show his results which aren't easy for non-specialists to understand. But it's worth the effort.

His analysis does seem to support the idea that we are a very early civilization in the Milky Way Galaxy, which is why we don't see any others. It doesn't really explain why we don't detect any traces of civilizations in other galaxies, unless life on Earth is so unlikely that we're not only the first intelligent species in the Milky Way but the first one in all the nearby galaxies. Which doesn't fit with what we know.

It's a paradox . . .