12-14-2014, 12:38 AM
Regarding the detection of alien civilizations, million year old or otherwise:
It's not really clear what a really advanced civilization would do on an ongoing basis that we could readily detect over interstellar distances, even if other civs are fairly common on the galaxy. IIRC even if we assume a million other civs in the galaxy that puts the nearest one about 300ly away. So what does that get us?
a) Most notions about what an alien (or future human) civilization might do with its time are built on the notion that a civ must/will grow in material and energy consumption until it has no choice but to limit itself. But current thinking on conservation and sustainability (and just plain birth control) indicate it might be possible (or even likely) for a civilization to hit the point of limiting its numbers (and resource needs) well before it hit the point of building a dyson or the like. If that is the case (and if that mode operates as a 'steady state' over the remaining lifetime of the civ, itself a notion that is debatable), then there would be much less or no need for things like dyson spheres or other megaengineering that might be detectable across interstellar distances.
b) Even if a civ was inclined to do mega-engineering we don't necessarily know what form it would take or how often it would take place. If a civ needs to detonate stars for raw materials but only needs to do it every 100,000yrs or so, we could have gone through our entire history to date without seeing it happen. If a civ has some kind of wormhole or warp drive based tech that lets them get around in a hurry, they might just boom stars that are already about to die, regardless of where they are and then transport useful stuff back home. In which case we might just see what we already do. If they are doing some form of megaengineering that involves goals and processes we haven't even thought of yet, we might not even recognize what we're seeing as engineering, even if we can detect it in the first place. Note that many megastructures in OA are built because someone just wants to, not because there is a real need for it.
c) Most SETI projects assume that aliens would be actively trying to communicate with other, lower tech, civs. There's no particular reason to think this is the case. This doesn't mean they aren't talking to each other, just that they aren't bothering to talk to us. Data transmissions between established hubs would likely be encrypted (and so look like noise to us) and would also likely use tight beams making them very difficult, perhaps impossible, for us to detect unless we happened to pass right through a beam.
Even if 'they' did want to talk to folks like us, the simplest option would see to be to wait until they detect our radio signals and then beam a message/send a probe to us. But if the nearest civ is 300ly away, they don't know about us yet and nothing will come of it from our end for centuries more.
d) It's possible to imagine models in which advanced civilizations (even those that carry out mega-engineering) are common, but very hard to spot at our level. The idea of an 'interstellar internet' would see lots of small (grapefruit size?) probes moving at low speeds across the galaxy and establishing hubs at various 'interesting' places. Each hub would be a store and forward point in the network. Civs would plug into their local hub and then be able to access the various 'web pages' of other civs, containing their knowledge and culture, possibly even after the originating civ is long gone. Data transfer between hubs would be by tight beams using encrypted (or at least very efficiently encoded) signals. To us, it might not look like much is happening.
A more energetic (but still hard to spot) model might be a mix of stay-at-homes who convert their solar systems into Matrioshka Brains or equivalent and settle down to living in huge virtual universes and explorers who use the Far Edge Party approach to rapidly explore the entire galaxy in a cosmic eyeblink of time. While they're at it they could transmit all of their findings back to their stay-at-home origin, effectively uploading the whole galaxy into virtuality. Any other civs they encounter could be contacted and put in touch with the stay-at-homes or worked with to continue the grand exploration.
Once the entire galaxy is explored, it seems unlikely that those inclined to do it are just going to stop. Rather they will probably pack up and take off for one or more other galaxies to continue the process.
The end result of this scenario is a galaxy of hard to spot megastructures radiating at near CBR temps and fleets of explorers zipping around in intergalactic space, spending millions of years or more in transit. Also hard to spot from our limited perspective.
As far as superintelligent AIs that have killed off their creators - I'm not sure a 'paperclip' AI of superhuman level would really be possible. This scenarios assumes that a 'baseline' intelligence could create a mind much more capable than itself but not so capable that it couldn't overcome any kind of behavioral restrictions the baseline minds tried to come up with.
Once we get past the paperclip scenarios, we are essentially back to the earlier mention of what an advanced (and possibly superhumanly intelligent) civ would do with its time and whether or not that activity would be noticeable or common enough to have been observed by us yet.
My 2c worth,
Todd
It's not really clear what a really advanced civilization would do on an ongoing basis that we could readily detect over interstellar distances, even if other civs are fairly common on the galaxy. IIRC even if we assume a million other civs in the galaxy that puts the nearest one about 300ly away. So what does that get us?
a) Most notions about what an alien (or future human) civilization might do with its time are built on the notion that a civ must/will grow in material and energy consumption until it has no choice but to limit itself. But current thinking on conservation and sustainability (and just plain birth control) indicate it might be possible (or even likely) for a civilization to hit the point of limiting its numbers (and resource needs) well before it hit the point of building a dyson or the like. If that is the case (and if that mode operates as a 'steady state' over the remaining lifetime of the civ, itself a notion that is debatable), then there would be much less or no need for things like dyson spheres or other megaengineering that might be detectable across interstellar distances.
b) Even if a civ was inclined to do mega-engineering we don't necessarily know what form it would take or how often it would take place. If a civ needs to detonate stars for raw materials but only needs to do it every 100,000yrs or so, we could have gone through our entire history to date without seeing it happen. If a civ has some kind of wormhole or warp drive based tech that lets them get around in a hurry, they might just boom stars that are already about to die, regardless of where they are and then transport useful stuff back home. In which case we might just see what we already do. If they are doing some form of megaengineering that involves goals and processes we haven't even thought of yet, we might not even recognize what we're seeing as engineering, even if we can detect it in the first place. Note that many megastructures in OA are built because someone just wants to, not because there is a real need for it.
c) Most SETI projects assume that aliens would be actively trying to communicate with other, lower tech, civs. There's no particular reason to think this is the case. This doesn't mean they aren't talking to each other, just that they aren't bothering to talk to us. Data transmissions between established hubs would likely be encrypted (and so look like noise to us) and would also likely use tight beams making them very difficult, perhaps impossible, for us to detect unless we happened to pass right through a beam.
Even if 'they' did want to talk to folks like us, the simplest option would see to be to wait until they detect our radio signals and then beam a message/send a probe to us. But if the nearest civ is 300ly away, they don't know about us yet and nothing will come of it from our end for centuries more.
d) It's possible to imagine models in which advanced civilizations (even those that carry out mega-engineering) are common, but very hard to spot at our level. The idea of an 'interstellar internet' would see lots of small (grapefruit size?) probes moving at low speeds across the galaxy and establishing hubs at various 'interesting' places. Each hub would be a store and forward point in the network. Civs would plug into their local hub and then be able to access the various 'web pages' of other civs, containing their knowledge and culture, possibly even after the originating civ is long gone. Data transfer between hubs would be by tight beams using encrypted (or at least very efficiently encoded) signals. To us, it might not look like much is happening.
A more energetic (but still hard to spot) model might be a mix of stay-at-homes who convert their solar systems into Matrioshka Brains or equivalent and settle down to living in huge virtual universes and explorers who use the Far Edge Party approach to rapidly explore the entire galaxy in a cosmic eyeblink of time. While they're at it they could transmit all of their findings back to their stay-at-home origin, effectively uploading the whole galaxy into virtuality. Any other civs they encounter could be contacted and put in touch with the stay-at-homes or worked with to continue the grand exploration.
Once the entire galaxy is explored, it seems unlikely that those inclined to do it are just going to stop. Rather they will probably pack up and take off for one or more other galaxies to continue the process.
The end result of this scenario is a galaxy of hard to spot megastructures radiating at near CBR temps and fleets of explorers zipping around in intergalactic space, spending millions of years or more in transit. Also hard to spot from our limited perspective.
As far as superintelligent AIs that have killed off their creators - I'm not sure a 'paperclip' AI of superhuman level would really be possible. This scenarios assumes that a 'baseline' intelligence could create a mind much more capable than itself but not so capable that it couldn't overcome any kind of behavioral restrictions the baseline minds tried to come up with.
Once we get past the paperclip scenarios, we are essentially back to the earlier mention of what an advanced (and possibly superhumanly intelligent) civ would do with its time and whether or not that activity would be noticeable or common enough to have been observed by us yet.
My 2c worth,
Todd