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> why would we colonize the galaxy? To explore. Yes, it may take generations to get anywhere, and no, we probably won't be sending resources back. > Terraform

> why would we colonize the galaxy? To explore. Yes, it may take generations to get anywhere, and no, we probably won't be sending resources back. > Terraforming would be extremely challenging Yes. Terraforming is a bad idea. Much better to mine asteroids and build large habitats in orbit. When it gets too crowded, move to the next star. No need to terraform planets to spread out into the galaxy. > "Tweaking the sun" is probably unfeasible We've got millions of years to work out how. I doubt it would be something as crude as crashing planets into it. > Similarly, adjusting Earth's orbit would require a colossal amount of energy and reaction mass Yes, but you'd have a colossal amount of time to move it. Light sails maybe — they use energy/mass from the sun itself. > Technological advancement has a ceiling determined by our resources and abilities, and that ceiling is almost certainly too low to accommodate a galactic civilization of stellar engineers. I don't know how you can know that. It's only a couple of hundred years since the scientific revolution — how can you possibly know what the limits will be over millions or billions of years?

bccdee 3y ago
> To explore But then why start a colony? If you're just looking around, then the massive investment to build a comfortable habitat isn't worthwhile. I think the incentives just don't line up; that's my Fermi paradox answer. I especially think it's unlikely that anyone would set off on an exploration where they were going to die of old age before ever seeing anything. > We've got millions of years to work out how. What if it isn't possible? The sheer scale involved suggests there's nothing to be done. It is a bonfire exponentially larger than all the mass we can conceivably bring to bear upon it in any way. When it burns out, it burns out. Moving the planet is a little more feasible [1], but doing it with solar sails would take about a billion years, even if the sail was 19x the diameter of Earth. An ion drive would be snappier, but we'd have to have effectively unlimited energy to make that happen, and we'd have to eject about a sixth of the Earth's mass from outside of the atmosphere on some sort of planetary gimbal. [1]: https://www.sciencealert.com/this-rocket-scientist-explains-how-we-could-hypothetically-move-the-planet https://www.sciencealert.com/this-rocket-scientist-explains-... > how can you possibly know what the limits will be Oh I can't. But there are limits, and we'll hit them eventually. The most obvious limits are energy and mass. We obviously can't do anything that would require more mass than exists in the solar system, and the ceiling for practically accessible mass for any given purpose is likely much lower. Some elements are quite rare. There may not be that much energy to go around. There are also likely soft time limits: A project that takes ten thousand years might simply be beyond us politically. Some tasks, like full comprehension of the human brain, might simply be too complicated to ever be realized. The longer you think about it, the more plausible limitations materialize.

bccdee 3y ago

> To explore But then why start a colony? If you're just looking around, then the massive investment to build a comfortable habitat isn't worthwhile. I think the incentives just don't line up; that's my Fermi paradox answer. I especially think it's unlikely that anyone would set off on an exploration where they were going to die of old age before ever seeing anything. > We've got millions of years to work out how. What if it isn't possible? The sheer scale involved suggests there's nothing to be done. It is a bonfire exponentially larger than all the mass we can conceivably bring to bear upon it in any way. When it burns out, it burns out. Moving the planet is a little more feasible [1], but doing it with solar sails would take about a billion years, even if the sail was 19x the diameter of Earth. An ion drive would be snappier, but we'd have to have effectively unlimited energy to make that happen, and we'd have to eject about a sixth of the Earth's mass from outside of the atmosphere on some sort of planetary gimbal. [1]: https://www.sciencealert.com/this-rocket-scientist-explains-how-we-could-hypothetically-move-the-planet https://www.sciencealert.com/this-rocket-scientist-explains-... > how can you possibly know what the limits will be Oh I can't. But there are limits, and we'll hit them eventually. The most obvious limits are energy and mass. We obviously can't do anything that would require more mass than exists in the solar system, and the ceiling for practically accessible mass for any given purpose is likely much lower. Some elements are quite rare. There may not be that much energy to go around. There are also likely soft time limits: A project that takes ten thousand years might simply be beyond us politically. Some tasks, like full comprehension of the human brain, might simply be too complicated to ever be realized. The longer you think about it, the more plausible limitations materialize.