5 ms·
It is complicated by the fact that this implies intelligent civilizations have a very finite window of opportunity in order to communicate. 500 Myr is a pretty
by cshimmin 12y ago
It is complicated by the fact that this implies intelligent civilizations have a very finite window of opportunity in order to communicate. 500 Myr is a pretty short on cosmic timescale; so the odds that:
1) our civilization comes to exist in some 500Myr window
2) another civilization comes to exist in another 500Myr window
3) Signals sent from that other civilization arrive at the right time for ours to observe them
are considerably lower than just the odds that two civilizations develop that are advanced enough to communicate with each other.
- Dylan16807 12y agoThose windows are pretty big. These aren't life-scouring cosmic rays, just mass extinctions. Complex life is still there, and can develop a civilization in a couple million years. The reshuffling of life could even increase the chances of a civilization occurring. And a smart species has pretty good odds of surviving a mass extinction.
- vorg 12y agoTo survive a mass extinction from gamma-ray bursts, a smart species would build a self-sustaining subterranean city with 1 million humans in residence at any one time, perhaps rotating in and out on tours. I'm sure the Chinese will have one within 50 years even if no-one else does. And such subterranean cities are also likely how humans will be living on Mars for thousands of years before it's terraformed.
- obstinate 12y agoIIUC Mars will never be terraformed because it is not heavy enough to hold on to atmosphere.
- firethief 12y ago50 years? We must not allow a mineshaft gap!
- adrianN 12y agoA subterranean city won't protect your from a GRB.
- Sophistifunk 12y agoWhy not, if the extinction mechanism is disruption of the ozone layer?
- knodi123 12y agoWell, my understanding could be wrong, but it seemed like the risk is to the ecosystem, not to human bodies directly. We personally don't need to be protected from the burst itself.
- cshimmin 12y agoI was actually basing this argument off of a similar one which gives much shorter windows (like ~1 Myr or something) as an upper bound on the amount of time a civilization can exit, which makes communication with other civilizations even more unlikely. This shorter bound comes from the very pessimistic notion that advanced civilizations will inevitably destroy themselves (e.g. nuclear holocaust). Obviously this one is a somewhat unfounded limit, but one could interpret the Fermi paradox as an empirical basis for the macabre hypothesis >:)
- lumpypua 12y ago> The reshuffling of life could even increase the chances of a civilization occurring. Bumping life out of a local maxima, lol.