5 ms·

That's awfully optimistic. For one, why would we colonize the galaxy? We probably can't beat lightspeed. It'll take generations to get anywhere, plus a huge up

by bccdee 3y ago

That's awfully optimistic. For one, why would we colonize the galaxy? We probably can't beat lightspeed. It'll take generations to get anywhere, plus a huge upfront investment, and for what? We can't send resources back, so it is not an investment. Terraforming would be extremely challenging, extremely slow, and would (if we were very, very lucky) still just get us a worse version of Earth. It just isn't a rational choice. "Tweaking the sun" is probably unfeasible. We could crash our entire planet into the sun and it'd have little effect. The sun is really really really big and we are really really really small. Similarly, adjusting Earth's orbit would require a colossal amount of energy and reaction mass which we just don't have, and probably never will. There's no reason to assume that humanity will inevitably advance through some exponential techno-apotheosis such that we'll eventually be able to do anything we want. Instead, it's much more sensible to assume technological growth will follow a sigmoid curve. 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.

perilunar 3y ago
> 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.
mmcdermott 3y ago
> For one, why would we colonize the galaxy? [...] It just isn't a rational choice. If things are universally good on Earth, then sure. Bear in mind that many of the European colonies that would become the United States were built by people fleeing situations in their home country. Of course, replicating that scenario still requires a lot of technological advancement and I agree that level of sophistication is not a given.
- bccdee 3y ago
  > If things are universally good on Earth, then sure. Bear in mind that the choice is between living on Earth vs spending the rest of your life in an extremely cramped spacecraft with the hope that, after several generations of spacecraft life and many more of terraforming, your great-great-great-to-the-nth-power grandchildren will have a nice home. Bear in mind too that destitute people will never be able to make this call; you'd need to be quite powerful to start this sort of program.
  - perilunar 3y ago
    Yeah, nobody would want that. But why assume the spacecraft will be cramped? They could well be extremely large rotating colonies, with an internal area equal to a large city or small country. And if you can build such craft, then why bother terraforming planets? Mine asteroids or planets for materials to make new colonies, study the stellar system, and move on to the next star when it gets a bit crowded.

by bccdee 3y ago

perilunar 3y ago

> 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.

mmcdermott 3y ago

> For one, why would we colonize the galaxy? [...] It just isn't a rational choice. If things are universally good on Earth, then sure. Bear in mind that many of the European colonies that would become the United States were built by people fleeing situations in their home country. Of course, replicating that scenario still requires a lot of technological advancement and I agree that level of sophistication is not a given.

bccdee 3y ago
> If things are universally good on Earth, then sure. Bear in mind that the choice is between living on Earth vs spending the rest of your life in an extremely cramped spacecraft with the hope that, after several generations of spacecraft life and many more of terraforming, your great-great-great-to-the-nth-power grandchildren will have a nice home. Bear in mind too that destitute people will never be able to make this call; you'd need to be quite powerful to start this sort of program.
- perilunar 3y ago
  Yeah, nobody would want that. But why assume the spacecraft will be cramped? They could well be extremely large rotating colonies, with an internal area equal to a large city or small country. And if you can build such craft, then why bother terraforming planets? Mine asteroids or planets for materials to make new colonies, study the stellar system, and move on to the next star when it gets a bit crowded.