Planets are indefensible, as is most of space if your orbit is predictable. All you need is a body bigger than your margin of computational error, and reaction mass.
> exponential growth
My point is that in order for civilization to be multi-starred, they'd need to communicate. Once a new star is colonized, due to the constraint on light speed, they become two separate civilizations. This means each star basically starts from the beginning, each time. So, if you estimate a couple of million years for a civilization to just to consider expanding... it'd take awhile. A lot more than a few million years to colonize the galaxy because not every star will consider expanding.
> the reason is resource competition.
Resources for what, exactly? Populations self-govern growth. It isn't always pretty, since over-population means a lot of deaths. But hungry people aren't going to say "I'm hungry so I'm going to build a space ship and hunt Space Cows. Who's coming with me?"
Further, there is no evidence that dinosaurs left this planet. They had 165 million years to do so. So, it doesn't 'just take' a few million years and there is no guarantee that a civilization will expand beyond a star. Sure, you could argue that dinosaurs probably weren't intelligent, but there's no evidence for that other than a small cavity size for brains; which doesn't necessarily mean they were stupid. Whales have bigger brains than humans, but I don't see them leaving the earth any time soon either.
My point is, even if you decide to colonize another planet, you are effectively cut off from your home. Technology WILL be lost since you basically have to restart manufacturing from nothing, with a small population at that, and there are a whole different set of filters to pass through. The odds of that civilization growing to the point of wanting to move on, without dying out itself, is remarkably low.
Interestingly, colonization of stars beyond a certain distance might even be impossible without some kind of artificial gravity or cryo. Especially if it requires multiple generations to arrive.
I really like this thread. Both make good points. I still land on space being really big and really hard. Maybe so much so that multi-stellar civilization is next to impossible and multi-galactic moreso.
If you think resources are scarce on Kepler-452b, wait til you see how bad things on the Space Mormon ship. Especially since it’s 60% harder to exit the gravity well than it would be on our destination at Sol-3. We used all our lift capabilities just to get the basics to orbit. Once we get out there, it’s 1400 light years away, so will take us 5600 years to get to Sol assuming we can get the drives going full speed and still retain enough delta-v to brake in Sol orbit. If not, it may even take longer or worse - we zoom by as a blip at the edge of the system. The good news is our telescopes are pretty sure it’s habitable, but we don’t hear any techno signatures. So with any luck we arrive in 6000 years and have enough gametes in storage for the incubators to build a viable colony from. I just hope the kids behave once they get there.
Planets are indefensible, as is most of space if your orbit is predictable. All you need is a body bigger than your margin of computational error, and reaction mass.
> exponential growth
My point is that in order for civilization to be multi-starred, they'd need to communicate. Once a new star is colonized, due to the constraint on light speed, they become two separate civilizations. This means each star basically starts from the beginning, each time. So, if you estimate a couple of million years for a civilization to just to consider expanding... it'd take awhile. A lot more than a few million years to colonize the galaxy because not every star will consider expanding.
> the reason is resource competition.
Resources for what, exactly? Populations self-govern growth. It isn't always pretty, since over-population means a lot of deaths. But hungry people aren't going to say "I'm hungry so I'm going to build a space ship and hunt Space Cows. Who's coming with me?"
Further, there is no evidence that dinosaurs left this planet. They had 165 million years to do so. So, it doesn't 'just take' a few million years and there is no guarantee that a civilization will expand beyond a star. Sure, you could argue that dinosaurs probably weren't intelligent, but there's no evidence for that other than a small cavity size for brains; which doesn't necessarily mean they were stupid. Whales have bigger brains than humans, but I don't see them leaving the earth any time soon either.
My point is, even if you decide to colonize another planet, you are effectively cut off from your home. Technology WILL be lost since you basically have to restart manufacturing from nothing, with a small population at that, and there are a whole different set of filters to pass through. The odds of that civilization growing to the point of wanting to move on, without dying out itself, is remarkably low.
Interestingly, colonization of stars beyond a certain distance might even be impossible without some kind of artificial gravity or cryo. Especially if it requires multiple generations to arrive.