This is an interesting topic and I enjoyed reading your post. I’d like to nitpick one point, though, which is the “stable, galaxy-wide civilization”. Specifically: I think a stable, galaxy-wide civilization would be surprising, for reasonable definitions of “stable civilization”. (This might not be disagreeing with you, since you just say there’s a decent chance of it, not that it’s the most likely outcome.)
Before getting into why it would be surprising, a note about why it matters: if in fact the future involves an ecosystem of many unstable civilizations instead, then our present moment is less crucial (though perhaps still wild). That’s because such a future would explore more possibilities for different types of civilizations, resulting in more Darwinian-like dynamics that give a result less dependent on starting conditions.
The problem for a galaxy-wide civilization is the speed of light. Assuming travel and communication are in fact limited by the speed of light (as present-day physics predicts), it will take ~100k years to send a message from one side of the Milky Way to the other. Even sending a message from here to Alpha Centauri takes ~4 years.
History makes it seem hard to maintain a coherent civilization with such long travel & communication delays. We’ve been living in a time of increasing civilizational coherency for the past few hundred years, but that could be caused by reduced travel & communication delays. In a galactic scenario, where travel & communication are limited by fundamental physics, the trend towards coherency would plausibly reverse.
I’ll return to galaxy-wide coherency in a moment, but assuming it doesn’t happen, that’s a problem for stability of civilizations because of inter-civilizational competition. If it’s possible to have a long-term stable civilization, I think it would require totalitarian control. But if your #1 priority is stability via totalitarian control, you may not do so well at competing with freer civilizations. As a contemporary example, North Korea is pretty good at maintaining a stable totalitarian regime, but it’s sacrificing GDP, technological development, etc. to do that. So the civilizations in the ecosystem should not be expected to be perfectly stable.
Returning to galaxy-wide coherency, you hint at an argument for why it may be possible:
I’ll also argue in a future piece that there is a chance of “value lock-in” here: whoever is running the process of space expansion might be able to determine what sorts of people are in charge of the settlements and what sorts of societal values they have, in a way that is stable for many billions of years.
It does seem at least conceivable that a sort of societal error-correction could maintain coherent values over long time-scales, and thus over long distances too, for similar reasons that we can store data digitally for long periods of time despite human memory being unstable.
But again I suspect this runs into problems with the speed of light. Assume perfect totalitarian control has not yet been achieved when galactic expansion starts. In that case, the initial phase of galactic expansion consists of frontier civilizations trying to expand as close as possible to c (the speed of light). If a particular civilization finds a way to expand at 0.3c when the next best is 0.2c, its descendants are going to dominate the galaxy, and splinter into many different civilizations themselves. This creates a Darwinian situation that selects for rapid expansion.
Since the most successful frontier civilizations are selected for rapid expansion, that’s their top priority. In general, there can only be one top priority, and since it’s not perfect totalitarian control, they probably won’t be perfectly totalitarian. Thus, this initial expansion phase seeds the galaxy with many differing civilizations descended from the frontier civilizations.
Once you have civilizational diversity throughout the galaxy, there’s no obvious way that can be reversed. I can’t see how else it could continue from there other than an ecosystem of civilizations. Something fundamental would need to change.
My biggest uncertainty here is about what if perfect totalitarian control is achieved before interstellar expansion. For reasons described earlier, I’d expect such a civilization to be eventually outcompeted by non-totalitarian aliens if there are any out there, but maybe there aren’t any of those. Maybe the whole thing depends on how doable perfect totalitarian control is relative to interstellar expansion.
This is an interesting topic and I enjoyed reading your post. I’d like to nitpick one point, though, which is the “stable, galaxy-wide civilization”. Specifically: I think a stable, galaxy-wide civilization would be surprising, for reasonable definitions of “stable civilization”. (This might not be disagreeing with you, since you just say there’s a decent chance of it, not that it’s the most likely outcome.)
Before getting into why it would be surprising, a note about why it matters: if in fact the future involves an ecosystem of many unstable civilizations instead, then our present moment is less crucial (though perhaps still wild). That’s because such a future would explore more possibilities for different types of civilizations, resulting in more Darwinian-like dynamics that give a result less dependent on starting conditions.
The problem for a galaxy-wide civilization is the speed of light. Assuming travel and communication are in fact limited by the speed of light (as present-day physics predicts), it will take ~100k years to send a message from one side of the Milky Way to the other. Even sending a message from here to Alpha Centauri takes ~4 years.
History makes it seem hard to maintain a coherent civilization with such long travel & communication delays. We’ve been living in a time of increasing civilizational coherency for the past few hundred years, but that could be caused by reduced travel & communication delays. In a galactic scenario, where travel & communication are limited by fundamental physics, the trend towards coherency would plausibly reverse.
I’ll return to galaxy-wide coherency in a moment, but assuming it doesn’t happen, that’s a problem for stability of civilizations because of inter-civilizational competition. If it’s possible to have a long-term stable civilization, I think it would require totalitarian control. But if your #1 priority is stability via totalitarian control, you may not do so well at competing with freer civilizations. As a contemporary example, North Korea is pretty good at maintaining a stable totalitarian regime, but it’s sacrificing GDP, technological development, etc. to do that. So the civilizations in the ecosystem should not be expected to be perfectly stable.
Returning to galaxy-wide coherency, you hint at an argument for why it may be possible:
It does seem at least conceivable that a sort of societal error-correction could maintain coherent values over long time-scales, and thus over long distances too, for similar reasons that we can store data digitally for long periods of time despite human memory being unstable.
But again I suspect this runs into problems with the speed of light. Assume perfect totalitarian control has not yet been achieved when galactic expansion starts. In that case, the initial phase of galactic expansion consists of frontier civilizations trying to expand as close as possible to c (the speed of light). If a particular civilization finds a way to expand at 0.3c when the next best is 0.2c, its descendants are going to dominate the galaxy, and splinter into many different civilizations themselves. This creates a Darwinian situation that selects for rapid expansion.
Since the most successful frontier civilizations are selected for rapid expansion, that’s their top priority. In general, there can only be one top priority, and since it’s not perfect totalitarian control, they probably won’t be perfectly totalitarian. Thus, this initial expansion phase seeds the galaxy with many differing civilizations descended from the frontier civilizations.
Once you have civilizational diversity throughout the galaxy, there’s no obvious way that can be reversed. I can’t see how else it could continue from there other than an ecosystem of civilizations. Something fundamental would need to change.
My biggest uncertainty here is about what if perfect totalitarian control is achieved before interstellar expansion. For reasons described earlier, I’d expect such a civilization to be eventually outcompeted by non-totalitarian aliens if there are any out there, but maybe there aren’t any of those. Maybe the whole thing depends on how doable perfect totalitarian control is relative to interstellar expansion.