Ok, now we are squeezing a comment way too far. Let me give you a fuller view: I am a neuroscientist, and I specialize in the biochemistry/biophysics of the synapse (and interactions with ER and mitochondria there). I also work on membranes and the effect on lipid composition in the opposing leaflets for all the organelles involved.

Looking at what happens during cryonics, I do not see any physically possible way this damage could ever be repaired. Reading the structure and "downloading it" is impossible, since many aspects of synaptic strength and connectivity are irretrievably lost as soon as the synaptic membrane gets distorted. You can't simply replace unfolded proteins, since their relative position and concentration (and modification, and current status in several different signalling pathways) determines what happens to the signals that go through that synapse; you would have to replace them manually, which is a) impossible to do without destroying surrounding membrane, and b) would take thousands of years at best, even if you assume maximally efficient robots doing it (during which period molecular drift would undo the previous work).

Etc, etc. I can't even begin to cover complications I see as soon as I look at what's happening here. I'm all for life extension, I just don't think cryonics is a viable way to accomplish it.

Instead of writing a series of posts in which I explain this in detail, I asked a quick side question, wondering whether there is some research into this I'm unaware of.

Does this clarify things a bit?

Showing 3 of 9 replies (Click to show all)

I will quickly remark that some aspects of this comment seem to betray a non-info-theoretic point of view. From the perspective of someone like me, the key question for cryonics are "Do two functionally different start states (two different people) map onto theoretically indistinguishable molecular end states?" You are not an expert on the future possibilities of molecular nanotechnology and will not be asked to testify as such, but of course we all accept that arbitrarily great physical power cannot reconstruct a canister of ash because the cr... (read more)

11RobinHanson7yNo doubt you can identify particular local info that is causally effective in changing local states, and that is lost or destroyed in cryonics. The key question is the redundancy of this info with other info elsewhere. If there is lots of redundancy, then we only need one place where it is held to be preserved. Your comments here have not spoken to this key issue.
5Merkle8yYou'll need to read Molecular Repair of the Brain [http://www.merkle.com/cryo/techFeas.html]. Note that it discusses a variety of repair methods, including methods which carry out repairs at sufficiently low temperatures (between 4K and 77K) that there is no risk that "molecular drift" would undo previous work. By making incredibly conservative assumptions about the speed of operations, it is possible to stretch out the time required to repair a system the size of the human brain to three years, but really this time was chosen for psychological reasons. Repairing a person "too quickly" seems to annoy people. You might also want to read Convergent Assembly [http://www.zyvex.com/nanotech/convergent.html]. As this is a technical paper which makes no mention of controversial topics, it provides more realistic estimates of manufacturing times. Total manufacturing time for rigid objects such as a human brain at (say) 20K are likely to be 100 to 1000 seconds. This does not include the time required to analyze your cryopreserved brain and determine the healthy state, which is likely to be significantly longer. Note that some alterations to the healthy state (the blueprints) will be required prior to manufacture, including various modifications to facilitate manufacture, the inclusion of heating elements for rewarming, and various control systems to monitor and modulate the rewarming and metabolic start-up processes as well as the resumption of consciousness. After you've had time to digest the paper, I'd be interested in your comments. As Ciphergoth has said, there are no (repeat no) credible arguments against the feasibility of cryonics in the extant literature. If you have any, it would be most interesting. As a neuroscientist, you might also be amused by Large Scale Analysis of Neural Structures [http://www.merkle.com/merkleDir/brainAnalysis.html]. For recent work on vitrification, I refer you to Greg Fahy at 21st Century Medicine.

Neil deGrasse Tyson on Cryonics

by bekkerd 1 min read9th May 2012107 comments

6


Question:

What are your thoughts on cryogenic preservation and the idea of medically treating aging?

His response:

A marvelous way to just convince people to give you money. Offer to freeze them for later. I'd have more confidence if we had previously managed to pull this off with other mammals. Until then I see it as a waste of money. I'd rather enjoy the money, and then be buried, offering my body back to the flora and fauna of which I have dined my whole life.

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