[Ultra-Tech] Conservative hard SF... but not implausibly conservative

[sir_pudding]

Originally Posted by Michael Thayne

Note, though, that I'm assuming technological advance grinds to a halt because we're being pessimistic about what's possible in the future, and eventually possible innovations are exhausted.

It isn't even especially pessimistic to say they'd be extinct.

[Andreas]

Originally Posted by Anthony

A problem for sapient beings is that brains have limited storage capacity; our learning rates vary significantly with age (the older you are, the slower you learn) and also involve a lot of forgetting. Basically any means for storing immortal memory in a finite brain involves some combination of extremely limited ability to form new memories and extremely aggressive purging of old memories.

Is the slowing of learning really because of the brain running out of information storage capacity? The upper bound estimates for how much the brain can store I remember reading about were very high.

There is also the possibility of storing some of your memories outside the brain (or expanding the brain). The storage capacity would of course still be finite, but it could very well be enough to last until the end of the universe.

Originally Posted by AlexanderHowl

I doubt that we will reach a Class II civilization ever. That is 3.8e26 W, which is around 2e14 times as much energy as we consume right now (by comparison, we have only increased our per capita energy consumption by x115 over the past two million years). If we assume that the per capita energy consumption will only increase by a similar factor over the next two million years, the population of humanity would need to increase by 1.7e12 in the Sol System to reach a Class II civilization within two million years.

One possible reason why advanced civilizations may not leave their home systems would be due to virtual reality. A TL11 civilization could support a virtual world with a complete cast of realistic characters for every inhabitant for as much expense as it would be to send a small colony to another star system via STL travel. If they have biological immortality and advanced non-volitional AI, they would probably prefer their virtual worlds within a connected virtual galaxy over the boredom and risk associated with STL travel to another star system. With biological immortality, there is also little need for reproduction beyond replacement through cloning, so the alien civilizations would probably cap out at 1 trillion people when their virtual worlds become a reality.

There is little reason for such a society to send colonies to other star systems. Just send enough AIs to build a self sufficient industry there. That gives them access to far more computing power (a return on investment they would even live to see due to biological immortality and a low risk VR lifestyle) and with such advanced technology, they could probably just sleep until the project is complete if they for some reason found a slightly less ridiculusly wealthy lifestyle unbearable.

Not being located in only a single system also helps protect them against potential existential risks such as hostile aliens.

There is very little reason for such a civilization not to spend the resources necessary to get interstellar expansion going. They would only have to do it once, then the other star systems could continue and they would eventually have access to all the resources in the galaxy.

Originally Posted by Michael Thayne

You know, I plucked the 10 million years figure out of a hat, but I just realized at 1% C, you're not actually going to colonize the entire galaxy in that time. Hmmm...

Why not? As I understand it, the farthest reaches of our galaxy is roughly 75000 light years away. At 1% of C, that would be just 7.5 million years. Multiply that by a modest factor to account for the extra time needed and you would probably get less than 10 million years.

[David Johnston2]

Originally Posted by Andreas

I

There is little reason for such a society to send colonies to other star systems. Just send enough AIs to build a self sufficient industry there. That gives them access to far more computing power

Unless they have faster than light communication I don't see how they have access to it.

[AlexanderHowl]

Why bother colonizing other star systems if your population is stable and your needs will be met for the next couple of billion years? A virtual reality addicted civilization would probably despise the idea of leaving their home star system because they would leave the virtual reality galaxy that represents the greatest achievement of their society. In such a stable society, only a million new people would occur every year and would find themselves vastly outnumbered by the people who have lived for tens or hundreds of thousand of years, so any ambitious change would be voted down because it would be seen as an unnecessary change.

The fact that we are not part of an interstellar civilization leads to two unsettling conclusions (the idea that we are the only one to ever exist is probably just an artifact of ignorance, much like the idea that only the Solar System possessed planets was before the 1990s). Either it is impossible for advanced civilizations to colonize other star systems or there is something that destroys them before they can spread too far. In either case, stable societies like the virtual reality addicts would survive for billions of years while more ambitious civilizations would disappear within a few hundred years after achieving STL colonization capabilities.

[Andreas]

Originally Posted by David Johnston2

Unless they have faster than light communication I don't see how they have access to it.

Computations aren't only useful when you get an instantaneous result. That is especially the case for people with such long lifespans. There is also the possibility of some of the people going there.

Originally Posted by AlexanderHowl

Why bother colonizing other star systems if your population is stable and your needs will be met for the next couple of billion years? A virtual reality addicted civilization would probably despise the idea of leaving their home star system because they would leave the virtual reality galaxy that represents the greatest achievement of their society. In such a stable society, only a million new people would occur every year and would find themselves vastly outnumbered by the people who have lived for tens or hundreds of thousand of years, so any ambitious change would be voted down because it would be seen as an unnecessary change.

The fact that we are not part of an interstellar civilization leads to two unsettling conclusions (the idea that we are the only one to ever exist is probably just an artifact of ignorance, much like the idea that only the Solar System possessed planets was before the 1990s). Either it is impossible for advanced civilizations to colonize other star systems or there is something that destroys them before they can spread too far. In either case, stable societies like the virtual reality addicts would survive for billions of years while more ambitious civilizations would disappear within a few hundred years after achieving STL colonization capabilities.

What makes you think that all their needs are being met? There are ways to make use of pretty much any amount of computational power. Unless they are very different from the humans who exist now, there will be many of them who wants more. Why would leaving be so unappealing? You could have an equally advanced VR in the other systems as well.

If something is destroying ambitious civilizations, the less ambitous ones wouldn't necessarily be spared either and if such a destroyer exists, but has yet to reach you, expanding might very well be the only way to defend yourself.

[Michael Thayne]

Originally Posted by Andreas

Why not? As I understand it, the farthest reaches of our galaxy is roughly 75000 light years away. At 1% of C, that would be just 7.5 million years. Multiply that by a modest factor to account for the extra time needed and you would probably get less than 10 million years.

Argh, I meant to say, "I picked the 1 million years figure out of a hat." Your math is correct.

[Michael Thayne]

The more I think about it, the more I like this thread about societal collapse. Here's a question—how badly can things go for a space-faring clade before they cease to be space-faring, or can only remain space-faring through incredible luck? I've dropped "civilization" for the objections already given, and I say "clade" rather than "species" because they'll likely spawn ancestor-species through both genetic engineering and unguided evolution.

If civilizational collapse is inevitable, it's quite possible that generation ships at 1% c are non-viable, or at least would require genetically re-engineering humans and/or innovative social structures to work. If AI is relatively limited, seedships full of embryos will face different problems. You might, though, see a kind of natural selection applied to sub-civilizations and sub-species, where the variety best suited to interstellar, slower-than-light colonization eventually becomes dominant.

I think once you start filling the asteroid belt with O'Neill cylinders, you're pretty well insulated against clade extinction. The thing about nuclear war is that, even if you miss a major city here or there, you can pretty thoroughly wreck the biosphere, wiping out all intelligent life on a planet. If two halves of a Dyson sphere went to war with each other, I don't know if they'd face the same threat. Or would they?

Another thing to note about colonizing a galaxy: some quick Googling and a back-of-the-envelope calculation makes me think Polynesia was colonized at about 100,000th of the rate it could have been colonized, had there been an organized effort to colonize it at the fastest possible speed the technology allowed. I don't know if something analogous makes any sense for interstellar colonization, it might not. But it's something to chew on.

[sir_pudding]

Originally Posted by Michael Thayne

The more I think about it, the more I like this thread about societal collapse. Here's a question—how badly can things go for a space-faring clade before they cease to be space-faring, or can only remain space-faring through incredible luck? I've dropped "civilization" for the objections already given, and I say "clade" rather than "species" because they'll likely spawn ancestor-species through both genetic engineering and unguided evolution.

The end of the first half of Seveneves.

[Michael Thayne]

Originally Posted by sir_pudding

The end of the first half of Seveneves.

Haven't read that one. I'll check it out.

[David Johnston2]

Originally Posted by Andreas

Computations aren't only useful when you get an instantaneous result.

Seems to me that if technological progress has ground to a halt then...yeah, computations are only useful when you get an instantaneous result.