This is, of course, not anywhere in anything that kalla724 or I said.
If you complain about how it would be hard to in-situ repair denatured proteins - instead of talking about how two dissimilar starting synapses would be mapped to the same post-vitrification synapse because after denaturing it's physically impossible to tell if the starting protein was in conformation X or conformation Y - then you're complaining about the difficulty of repairing functional damage, i.e., the brain won't work after you switch it back on, which is completely missing the point.
If neuroscience says conformation X vs. conformation Y makes a large difference to long-term spiking input/output, which current neuroscience holds to be the primary bearer of long-term brain information, and you can show that denaturing maps X and Y to identical end proteins, then the ball has legitimately been hit back into the court of cryonics because although it's entirely possible that the same information redundantly appears elsewhere and the brain as a whole still identifies as single person and their personality and memories, telling us that cryonics worked would now tell us a new fact of neuroscience we didn't previously know (e.g. that the long-term behavior of this synapse was reflected in a distinguishable effect on the chemical balance of nearby glial cells or something). But currently, if we find out that cryonics doesn't work, we must have learned some new fact of neuroscience about informationally important brain information not visible in vesicle densities, synaptic configurations, and other things that current neuroscience says are important and that we can see preserved in vitrified rat brains.
We don't have current tech for getting info out. There's solid foreseeable routes in both nanoimaging and nanodevices. If the molecules are in-place with sufficient resolution, sufficiently advanced and foreseeable future imaging tech or nanomanipulation tech should be able to get the info out. Like, Nanosystems level would definitely be sufficient though not necessary, and those are some fairly detailed calculations, estimates, and toy systems being bandied about.
There are a lot of steps that all need to go correctly for cryonics to work. People who had gone through the potential problems, assigning probabilities, had come up with odds of success between 1:4 and 1:435. About a year ago I went through and collected estimates, finding other people's and making my own. I've been maintaining these in a googledoc.
Yesterday, on the bus back from the NYC mega-meetup with a group of people from the Cambridge LessWrong meetup, I got more people to give estimates for these probabilities. We started with my potential problems, I explained the model and how independence works in it [1]. For each question everyone decided on their own answer and then we went around and shared our answers (to reduce anchoring). Because there's still going to be some people adjusting to others based on their answers I tried to randomize the order in which I asked people their estimates. My notes are here. [2]
The questions were:
To see people's detailed responses have a look at the googledoc, but bottom line numbers were:
(These are all rounded, but one of the two should have enough resolution for each person.)
The most significant way my estimate differs from others turned out to be for "the current cryonics process is insufficient to preserve everything". On that question alone we have:
My estimate for this used to be more positive, but it was significantly brought down by reading this lesswrong comment:
In the responses to their comment they go into more detail.
Should I be giving this information this much weight? "many aspects of synaptic strength and connectivity are irretrievably lost as soon as the synaptic membrane gets distorted" seems critical.
Other questions on which I was substantially more pessimistic than others were "all cryonics companies go out of business", "the technology is never developed to extract the information", "no one is interested in your brain's information", and "it is too expensive to extract your brain's information".
I also posted this on my blog
[1] Specifically, each question is asking you "the chance that X happens and this keeps you from being revived, assuming that all of the previous steps all succeeded". So if both A and B would keep you from being successfully revived, and I ask them in that order, but you think they're basically the same question, then A basically only A gets a probability while B gets 0 or close to it (because B is technically "B given not-A")./p>
[2] For some reason I was writing ".000000001" when people said "impossible". For the purposes of this model '0' is fine, and that's what I put on the googledoc.