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Joshua_Blaine comments on You Only Live Twice - Less Wrong

86 Post author: Eliezer_Yudkowsky 12 December 2008 07:14PM

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Comment author: Joshua_Blaine 04 September 2013 09:31:24PM 10 points [-]

I understand this is from ages ago but is worth a response. See the Wiki page on Deep hypothermic circulatory arrest (a procedure used in some surgeries today):

Deep Hypothermic Circulatory Arrest (DHCA) is a surgical technique that involves cooling the body of the patient and stopping blood circulation.

The procedure requires keeping the patient in a state of hibernation at 12 - 18 degrees Celsius with no breathing, heartbeat, or brain activity for up to one hour. Blood is drained from the body to eliminate blood pressure. [emphasis mine]

The existence and success of this procedure seems like incredibly strong evidence in favor of people having a purely chemical identity stored in their head. When timely applied and non-lossy preservation techniques (which I consider modern cryonics to be) are used, you should be able to be successfully re-animated.

Comment author: Moss_Piglet 07 September 2013 11:43:14PM 2 points [-]

There's a bit of a difference, as I'm sure you're aware, between being refrigerated for seven minutes and frozen for a decade or more. Proteins denature, lipid membranes break down, cells and tissues are destroyed either by expanding liquids or toxic antifreeze compounds.

Some of that damage might be reversible. Much could well be to fungible parts of the body; having to replace an ear or a spleen shouldn't overly impact whether the reanimated person is you or not. But in the absence of knowledge about how / where "chemical identity" is stored in the brain and how vulnerable those systems are to damage (much less how one would go about putting the bits back together), it is preposterous to make a definite claim that cryonics is reversible.

Some damage cannot be reversed, some information cannot be recovered/decrypted within the time until heat death, and there is not sufficient evidence to believe that a frozen brain is any less 'erased' than a letter which has been dissolved in acid.

Comment author: somervta 08 September 2013 12:51:27AM 12 points [-]

There is, in fact, ridiculously good evidence to think that more information is preserved by cryonics than a letter dissolved in acid. The incredibly important question is 1) How much information is preserved, and 2) whether it is the right information.