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One thing a lot of discussion of the Drake equation get wrong is that they assume the average lifetime of a civilisation is a few hundred years. However, while there are speculative ideas about nuking the Sun,, the harsh reality is that there are no known technological way to destroy civilisation so thoroughly it doesn't rebuild in a few hundred years. Nuclear war, global warming or a bioengineered plague never kill everyone; 99.99% mortality is a blip on a graph on a large enough scale. 100% never happens by accident. So one of the most plausible long term futures is an endless drunken walk between the 17th to 21st C. Which means the total time spent in the radio-spewing 20C is indefinitely large, probably hundreds of millions of years. But civilisations doing that would be hard to spot by current tech at anything greater than a few light years. So there could be billions of technological civilisations in this galaxy alone.
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Aug 24, 2016 14:08
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Ytlaya posted:People probably wouldn't have to reinvent how to build a nuclear power plant, for example. Lack of fossil fuels, when they eventually run out on Civilisation 10.0 or something, would change things somewhat. It'd be hard to mine uranium with a pick axe. But i don't see why you couldn't build a small hydro plant or windmill manually and then expand from there. Plus 9 catastrophes out of 10 there would be at least one country left with a working power plant. Solar, wind, probably seawater uranium are not going to run out until the Sun leaves the main sequence.(5 billion years or so). The 18C led inexorably to the 19th; it seems to really take some kind of motivated reasoning to imagine it could ever continue indefinitely. On the plus side, 5 billion years is enough time for a large enough statistical sample of civilisations that you can be confident every population group will get their fair share of time having a go on the Maxim gun.
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Aug 25, 2016 08:20
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A White Guy posted:The planet won't be inhabitable for 5 billion years. I forget where I read this, but as solar radiation increases over the millenias, the planet will get less and less habitable. The projections were that the planet would stop being habitable within the next billion years, on a timescale that's well beyond the lifespan of our civilization but pretty soon, in galactic terms. That's true. On the other hand a steady state rise-and-collapse civilisation might get to the point of being able to setup/fix mitigation measures every thousand years or so. Even if not, a billion years is a pretty long time. quote:Radiation isn't just something that we as a species could just adapt to. We're not fungus, though human ingenuity is very impressive. There are simply some challenges that are impossible to mount, and a full-scale MAD style nuclear war might be one of them. Unlikely; the usual estimated global impact of exploding every nuke that ever existed is about a 1% rise in background radiation. Which wouldn't even be noticeable, except within a society that's publishing scientific papers on cancer rates. You could probably do better if you really tried, with a cobalt bomb, or nuking the Sun. But that's all hypothetical technology that doesn't actually exist. If you are going to get hypothetical, hyper-tech aliens would doubtless have a wide arrange of means of wiping out all life, and probably physically destroying the Earth. Less hypothetically, plenty of natural phenomena could get the job done too, though I think the jury is currently out on any being statistically expected within a billion years.
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Aug 25, 2016 13:15
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A Buttery Pastry posted:
That's a list of reasons why you might end up in the 17C as opposed to '21C but some people are dead'. If you lose the ability to economically organise anything larger than a village, then any specialist occupation that doesn't pay off at that scale is non-viable. Which means you can have a blacksmith, a priest, and maybe a schoolteacher and doctor. Nothing more. But that's enough to maintain literacy , which means anything that has ever been invented you know about. Which is why it's 17C(ish), not before . Although 'contemporary isolated 3rd world village' might actually be a better mental model. To go below that, you have to destroy everything at village scale, leaving only isolated individuals. And even if you somehow did do that, that would only delay the process of civilisation reforming by a few hundred or thousand years.
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Aug 25, 2016 17:16
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