Very much disagree on space colonies as hedge against human extinction. I could write a more detailed critique, but the bottom line is there is no x-risk severe enough to wipe out all (not merely 99.999%) humans on Earth but at the same time not severe enough to also wipe out all moon/Mars colonies.
I think this is a good point. Civilization may eventually recover from some catastrophic risks (e.g. nuclear war). And some risks are so severe that even Mars would not be safe (e.g. UFAI).
But are there no risks that could wipe out humanity on Earth that wouldn’t also kill a Mars colony? A comet impacting the Earth might be at the right scale for that. Or maybe a runaway greenhouse effect triggered by our carbon emissions.
And what do you think about using space colonies as a hedge against the collapse of civilization (rather than extinction)?
But are there no risks that could wipe out humanity on Earth that wouldn’t also kill a Mars colony? A comet impacting the Earth might be at the right scale for that. Or maybe a runaway greenhouse effect triggered by our carbon emissions.
I have thought about both scenarios and, no, I don’t think either is plausible. I find natural x-risks not worth defending against in general due to their unlikelihood and lack of severity. If a planet allows complex but non-technological life to exist for hundreds of millions of years, it has nothing to throw at us in the next few hundred years.
Regarding meteor impact specifically, I think a comet would have to be significantly bigger than the one that caused the Chicxulub crater and failed to wipe out the dinosaurs. Birds are not close cousins of dinosaurs, they are the direct descendants; and had that meteor missed the Earth, dinosaurs would likely have evolved into something that looks very different than what walked the Earth 65 million years ago anyway, just like how we look very different to early mammals.
We, like the dinosaurs, are spread all over the Earth across every climate zone. Unlike the dinosaurs, we have technology at our disposal from stone tools to computers. Even the ruins of our civilization will provide many useful tools to ensure the survival of at least the tiniest fraction of humanity. I believe we are far more resilient than dinosaurs which again, survived the Chicxulub impact.
Since the distribution of meteor sizes follows a power law, it’s unlikely for Earth to encounter a comet/asteroid large enough to wipe out humanity outright until the sun becomes a Red Giant, let alone the next few centuries.
But if we were to hedge against such an impact, the most cost-effective way would be to create large underground bunkers with infrastructure and industry to keep a small isolated civilization running indefinitely. If we can build a self-sufficient colony on Mars, we sure as hell could do it on Earth.
Regarding runaway greenhouse effect, we have geological records testifying CO2 concentrations above 1000 ppm in the Cretaceous period which didn’t cause a runaway greenhouse, and I expect climate catastrophes to limit our ability to pump more CO2 into the atmosphere well before then through regional economic collapse. Since it’s a gradual process, there is also time for negative feedback like plant growth to kick in, and for drastic geoengineering efforts such as deliberately setting off a nuclear winter.
My favorite example of a one-planet x-risk (at first glance) is a microscopic black hole swallowing the Earth. Since a black hole with Earth’s mass would follow the same orbit, you’d think it won’t have any effect on the rest of the solar system. (Un)fortunately, there is 1) no physics grounding for the thesis that such a black hole would be stable and 2) the energy released in such an event would be akin to setting off a supernova inside the solar system and nuking everything from here to Pluto.
I’m not sure what you mean by “hedging against the collapse of civilization”. A Mars colony doesn’t stop civilization from collapsing on Earth. It would help avoid a delay in technological progress from a collapse, but in the long run a delay of a few centuries is of no particular importance.
I think this is a good point. Civilization may eventually recover from some catastrophic risks (e.g. nuclear war). And some risks are so severe that even Mars would not be safe (e.g. UFAI).
But are there no risks that could wipe out humanity on Earth that wouldn’t also kill a Mars colony? A comet impacting the Earth might be at the right scale for that. Or maybe a runaway greenhouse effect triggered by our carbon emissions.
And what do you think about using space colonies as a hedge against the collapse of civilization (rather than extinction)?
I have thought about both scenarios and, no, I don’t think either is plausible. I find natural x-risks not worth defending against in general due to their unlikelihood and lack of severity. If a planet allows complex but non-technological life to exist for hundreds of millions of years, it has nothing to throw at us in the next few hundred years.
Regarding meteor impact specifically, I think a comet would have to be significantly bigger than the one that caused the Chicxulub crater and failed to wipe out the dinosaurs. Birds are not close cousins of dinosaurs, they are the direct descendants; and had that meteor missed the Earth, dinosaurs would likely have evolved into something that looks very different than what walked the Earth 65 million years ago anyway, just like how we look very different to early mammals.
We, like the dinosaurs, are spread all over the Earth across every climate zone. Unlike the dinosaurs, we have technology at our disposal from stone tools to computers. Even the ruins of our civilization will provide many useful tools to ensure the survival of at least the tiniest fraction of humanity. I believe we are far more resilient than dinosaurs which again, survived the Chicxulub impact.
Since the distribution of meteor sizes follows a power law, it’s unlikely for Earth to encounter a comet/asteroid large enough to wipe out humanity outright until the sun becomes a Red Giant, let alone the next few centuries.
But if we were to hedge against such an impact, the most cost-effective way would be to create large underground bunkers with infrastructure and industry to keep a small isolated civilization running indefinitely. If we can build a self-sufficient colony on Mars, we sure as hell could do it on Earth.
Regarding runaway greenhouse effect, we have geological records testifying CO2 concentrations above 1000 ppm in the Cretaceous period which didn’t cause a runaway greenhouse, and I expect climate catastrophes to limit our ability to pump more CO2 into the atmosphere well before then through regional economic collapse. Since it’s a gradual process, there is also time for negative feedback like plant growth to kick in, and for drastic geoengineering efforts such as deliberately setting off a nuclear winter.
My favorite example of a one-planet x-risk (at first glance) is a microscopic black hole swallowing the Earth. Since a black hole with Earth’s mass would follow the same orbit, you’d think it won’t have any effect on the rest of the solar system. (Un)fortunately, there is 1) no physics grounding for the thesis that such a black hole would be stable and 2) the energy released in such an event would be akin to setting off a supernova inside the solar system and nuking everything from here to Pluto.
I’m not sure what you mean by “hedging against the collapse of civilization”. A Mars colony doesn’t stop civilization from collapsing on Earth. It would help avoid a delay in technological progress from a collapse, but in the long run a delay of a few centuries is of no particular importance.