Topic: Can we compute back the Universe to revive everyone?
Quality / epistemic status: I’m just noting this here for now. Language might be a bit obscure, and I don’t have a super robust/formal understanding of this. Extremely speculative.
The map can’t be larger than the territory. So you need a larger territory to scan your region of interest: your scanner can’t scan themselves. The region of interest is the future info-cone of the civilisation you want to compute back. Your reachable-cone is strictly less than a past info-cone. So it seems impossible to compute it back. Except:
a) If you prevent too much info from leaking in the broaded info cone (ex.: by cryopreserving a brain, the info stays in one place instead of chaotically spreading in the world).
b) If the Universe collapses on itself, then maybe the reachable-cone becomes the same size as the info-cone, and maybe at that point you can safety exit the sphere of interest with info leaking, but it seems unlikely; seems like a brain destroyed ten thousand years ago might now be spread over the whole world (ie. needing the whole world to be computed back; or at least, not being able to know which part you don’t need to compute it back).
c) An alien civilisation outside the info-cone might be able to scan it entirely during a collapse of the universe.
d) Our simulators would be able to compute it backwards.
But actually, b) and c) might not work because the leaking also happens across Everett branches, so the info-cone has one more dimension which might never become reachable. In other words, our future would have multiple possible pasts. To truly compute it back, we would need to compute back from each Everett branch at the same time or something like that AFAIU.
Topic: Can we compute back the Universe to revive everyone?
Quality / epistemic status: I’m just noting this here for now. Language might be a bit obscure, and I don’t have a super robust/formal understanding of this. Extremely speculative.
This is a reply to: https://www.reddit.com/r/slatestarcodex/comments/itdggr/is_there_a_positive_counterpart_to_red_pill/g5g3y3a/?utm_source=reddit&utm_medium=web2x&context=3
The map can’t be larger than the territory. So you need a larger territory to scan your region of interest: your scanner can’t scan themselves. The region of interest is the future info-cone of the civilisation you want to compute back. Your reachable-cone is strictly less than a past info-cone. So it seems impossible to compute it back. Except:
a) If you prevent too much info from leaking in the broaded info cone (ex.: by cryopreserving a brain, the info stays in one place instead of chaotically spreading in the world).
b) If the Universe collapses on itself, then maybe the reachable-cone becomes the same size as the info-cone, and maybe at that point you can safety exit the sphere of interest with info leaking, but it seems unlikely; seems like a brain destroyed ten thousand years ago might now be spread over the whole world (ie. needing the whole world to be computed back; or at least, not being able to know which part you don’t need to compute it back).
c) An alien civilisation outside the info-cone might be able to scan it entirely during a collapse of the universe.
d) Our simulators would be able to compute it backwards.
But actually, b) and c) might not work because the leaking also happens across Everett branches, so the info-cone has one more dimension which might never become reachable. In other words, our future would have multiple possible pasts. To truly compute it back, we would need to compute back from each Everett branch at the same time or something like that AFAIU.
There are several other (weird) ideas to revive everyone:
send a nanobot via wormhole in the past, it will replicate and collect all data about the brains
find a way to travel between everett branches. For every person there is branch where he is cryopreserved.
use quantum randomness generator to generate every possible mind in different everett branches