Yes there is some metabolic activity in hypothermia patients. However, metabolic activity isn't the reason for no ice crystal formation in hypothermia patients.
Sorry, my reply came out differently from what it sounded like in my head. What I meant to say was something like, "hypothermia patients still undergo noticeable metabolic activity, as opposed to cryonic patients, because the temperatures involved are much higher (among other reasons)". So, you and I mostly agree here; still, what I tried to say is that hypothermia and cryopreservation are not entirely analogous.
The brain has a higher degree of vascularization than other organs, which is positive for cryonics purposes.
Can you explain why ? Is this because the higher density of blood vessels allows for higher densities of cryoprotectants to be delivered ? But isn't this advantage offset by the disadvantage of having a more delicate structure that needs to be preserved ? AFAIK, you can lose a chunk of liver or a piece of skin with only a minor loss of function, but losing a piece of brain is a different story.
In any case, is there a reason why we can freeze and revive a rabbit kidney, but not a human one ?
Cracking due to temperature differentials is macroscopic in vitrification, thus doesn't apply to "cells" so much as to tissues.
That actually sounds worse, not better...
Largely prevented (under ideal conditions) with prompt cooling.
How prompt are we talking here ? And isn't this requirement at odds with your other comments ?
I don't know why your interpretation of the phrase "deal-killer" would exclude the possibility of repairs using future technology.
Fair enough, I think I interpreted your comment too strongly. As for the future technologies, you bring up molecular nanotech, molecular biotech (for lack of a better word; MBT for short), and uploading (which I do accept as a continuation of self, so at least we can agree on this point). You say that the "most compelling arguments against MNT are because it would be too fragile to work in warm, wet conditions"; I actually don't think that this is the most compelling argument against MNT, but that's another topic. I also believe that uploading will require some sort of MNT, or something very close to it.
The problem I have with MNT and MBT is twofold:
This entire talk of "future technologies" sounds a little hand-wavy to me, to be honest. Yes, I understand that all kinds of really awesome future technologies could hypothetically exist, but I would need to see some compelling evidence before I become convinced that they are likely to exist.
I was referring to the outcomes of cryobiology experiments. You can experiment with new cryoprotectants and get meaningful results right away. ... With anti-aging interventions by contrast, you cannot tell whether something is helping until the experimental animal reaches old age.
Oh, ok, I see what you meant. I have a few objections, though (as you probably knew I would, heh):
Don't get me wrong, I'm not saying that cryonics is a generally bad idea. I'm just saying that, as of today, there are better ways to spend your resources (i.e., money).
For the sake of argument let's assume the worst case regarding current cryopreservation technology. Assume it does too much damage to work regardless of what future tech is possible. That does not rule out advancements in cryopreservation tech in the near term that permit either a) good enough, or b) perfect preservation of the brain (or the full body for that matter) within our lifetimes, without needing to achieve anything approaching MNT or what you term MBT. So this is an independent variable.
Cryobiology has a solid track record of progress, to the poi...
From Mike Darwn's Chronopause, an essay titled "Would You Like Another Plate of This?", discussing people's attitudes to life:
Conclusion, graphs, and references in article. As usual, I recommend reading Chronopause.com as Darwin has many good articles; to quickly link a few: