In June 2012, Robin Hanson wrote a post promoting plastination as a superior to cryopreservation as an approach to preserving people for later uploading. His post included a paragraph which said:
We don’t actually know that frozen brains preserve enough brain info. Until recently, ice formation in the freezing process ripped out huge brain chunks everywhere and shoved them to distant locations. Recent use of a special anti-freeze has reduced that, but we don’t actually know if the anti-freeze gets to enough places. Or even if enough info is saved where it does go.
This left me with the impression that the chances of the average cryopreserved person today of being later revived aren't great, even when you conditionalize on no existential catastrophe. More recently, I did a systematic read-through of the sequences for the first time (about a month 1/2 ago), and Eliezer's post You Only Live Twice convinced me to finally sign up for cryonics for three reasons:
- It's cheaper than I realized
- Eliezer recommended Rudi Hoffman to help with the paperwork
- Eliezer's hard drive analogy convinced me the chances of revival (at least conditionalizing on no existential catastrophe) are good
Note: Signing of this letter does not imply endorsement of any particular cryonics organization or its practices. Opinions on how much cerebral ischemic injury (delay after clinical death) and preservation injury may be reversible in the future vary widely among signatories.
I don't find that terribly encouraging. So now I'm back to being pessimistic about current cryopreservation techniques (though I'm still signing up for cryonics because the cost is low enough even given my current estimate of my chances). But I'd very much be curious to know if anyone knows what, say, Nick Bostrom or Anders Sandberg think about the issue. Anyone?
Edit: I'm aware of estimates given by LessWrong folks in the census of the chances of revival, but I don't know how much of that is people taking things like existential risk into account. There are lots of different ways you could arrive at a ~10% chance of revival overall:
- (50% chance of no existential catastrophe) * (30% chance current cryopreservation techniques are adequate) * (70% chance my fellow humans will come through for me beyond avoiding existential catastrophe) = 10.5%
is one way. But:
- (15% chance no existential catastrophe) * (99% chance current cryopreservation techniques are adequate) * (70% chance my fellow humans will come through for me beyond avoiding existential catastrophe) = ~10.4%
is a very similar conclusion from very different premises. Gwern has more on this sort of reasoning in Plastination versus cryonics, but I don't know who most of the people he links to are so I'm not sure whether to trust them. He does link to a breakdown of probabilities by Robin, but I don't fully understand the way Robin is breaking the issue down.
I wish I could give you more up-votes for explicitly making existential catastrophe part of your calculations, too many people focus on the technical considerations to the exclusion of other relevant unknowns.
Here are mine (explanation of edit-- oops, patternists being wrong and right didn't sum to 1, fixed now):
Cryo
(50% not being ended by an intervening existential catastrophe) x
(80% fellow humans come through) x
[(70% patternists are wrong) x (50% cryo sufficient to preserve whatever it is I call my continuity strictly by repairing my original instance) +
(30% patternists are right) x (70% cryo sufficient to preserve whatever it is I call my continuity by any means)]
= 22.4%
Plastination
(70% not being ended by an intervening existential catastrophe) x
(85% fellow humans will through) x
[(70% patternists are wrong) x (0% plastination sufficient to preserve whatever it is I call my continuity by any means) +
(30% patternists are right) x (90% plastination sufficient to preserve whatever it is I call my continuity by any means)]
= 16.065%
Explanations: among existential risks I count human-made problems that would prevent people who would revive me from doing so. So, fellow humans coming through simply means there is someone at any point in the future willing and able to revive me conditioned on no existential catastrophes and it being technically possible to revive me at all.
For patternists to be right, both the following would have to be true...
A sufficiently accurate representation of you is you (to the point that your amplitude would sum over all such representations that you coexist with).
It is theoretically possible to achieve such a representation by uploading or reconstruction with molecular precision or some other reconstruction or simulation technique.
... or the following has to be true:
It's unlikely that patternists can be right in the first way because there is no evidence that very-very-similar configurations can validly be substituted for identical configurations. Especially if the replica in question did not evolve from the original and even more so if the replica is running on a completely different substrate than the original. Even if they are right in that way, will it ever be possible to test experimentally?
It is far more likely that patternists are right in the second way. My terminal goal is continuity (and I value accurate preservation of the data in my brain only because I think it is instrumental to preserving continuity). The main reason I am signed up for cryonics is because I believe it is more likely to succeed than any currently available alternative. If all alternatives are fundamentally doomed to failure, the entire question becomes largely moot. I'm therefore conditioning my above probabilities on the patternists not being right in the second way.
If continuing inner narrative is an illusion, and you find yourself in a simulation, then you could very well realize your dream of meeting a "the real Mickey Mouse." If we can be accurately simulated, why not living cartoons as well? A lot becomes possible by getting rid of identity-related illusions.