I am confused about your description who “handles” what. Especially for threats that move at the speed of light (solar flares, super flares, super nova explosions, gamma ray blasts, quasar ignition &c), it seems like the only option is increasing civilizational robustness, right? Additionally, you say that for rogue celestial bodies, “Managing this threat is futile”, which is true at the current level of technology, but if we had the energy of our sun available, surely we could redirect the path of such an object if detected early enough?
The only threat that looks like it truly falls into the category “unmanageable” is false vacuum decay, except maybe by interspersing as much as possible in the reachable universe, and avoiding destabilising fundamental physics experiments (though, ah, fictional evidence).
I don’t think there’s anything we can do right now about rogue celestial bodies—so not worth thinking about for me.
For space weather stuff like solar flares, the main jobs are proofing technology against high amounts of radiation, especially when it comes to nuclear reactors and national defence infrastructure. Researching exactly what the impacts might be from different threats, and their probabilities, would definitely help governments defend against these threats more effectively.
but if we had the energy of our sun available, surely we could redirect the path of such an object if detected early enough?
Momentum is the limiting factor. Even redirecting all of the sun’s light in the same direction only gets you about 1018 N of force. That’s enough to accelerate a solar mass by a whopping 10−13 m/s2, so you’re going to need to see it coming millions of years out. Doing better than that would require somehow ejecting a significant amount of reaction mass from the solar system.
The story I know is that if you can change the course of such an object by a slight amount early enough, that should be sufficient to cause significant deviations late in its course. Am I mistaken about this, and the force is not strong enough because the deviation is far too small?
For a freely moving mass, yes, though “early enough” can be arbitrarily early depending on how much impulse you have to work with. But stars in a galaxy aren’t freely moving. They’re on highly chaotic trajectories, with characteristic timescales on the order of (very roughly) ~1MYr.
This is a great post, strong upvote.
I am confused about your description who “handles” what. Especially for threats that move at the speed of light (solar flares, super flares, super nova explosions, gamma ray blasts, quasar ignition &c), it seems like the only option is increasing civilizational robustness, right? Additionally, you say that for rogue celestial bodies, “Managing this threat is futile”, which is true at the current level of technology, but if we had the energy of our sun available, surely we could redirect the path of such an object if detected early enough?
The only threat that looks like it truly falls into the category “unmanageable” is false vacuum decay, except maybe by interspersing as much as possible in the reachable universe, and avoiding destabilising fundamental physics experiments (though, ah, fictional evidence).
I don’t think there’s anything we can do right now about rogue celestial bodies—so not worth thinking about for me.
For space weather stuff like solar flares, the main jobs are proofing technology against high amounts of radiation, especially when it comes to nuclear reactors and national defence infrastructure. Researching exactly what the impacts might be from different threats, and their probabilities, would definitely help governments defend against these threats more effectively.
Momentum is the limiting factor. Even redirecting all of the sun’s light in the same direction only gets you about 1018 N of force. That’s enough to accelerate a solar mass by a whopping 10−13 m/s2, so you’re going to need to see it coming millions of years out. Doing better than that would require somehow ejecting a significant amount of reaction mass from the solar system.
The story I know is that if you can change the course of such an object by a slight amount early enough, that should be sufficient to cause significant deviations late in its course. Am I mistaken about this, and the force is not strong enough because the deviation is far too small?
For a freely moving mass, yes, though “early enough” can be arbitrarily early depending on how much impulse you have to work with. But stars in a galaxy aren’t freely moving. They’re on highly chaotic trajectories, with characteristic timescales on the order of (very roughly) ~1MYr.