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This is an archive page, last updated 16 July 2022. Please do not make edits to this page.
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Long term notes (sticky)[edit]

  • "Freezing": Let it be taken as a given that when someone refers to freezing living/recently dead tissue, they mean reducing its temperature to the liquid nitrogen range, using all available means to prevent the formation of destructive ice crystals (such as the "vitrification" process).

I wanted to add the first note to reduce silly correction battles over terminology; the second got archived and without the link here no one will ever go mock my essay. Thank you. ħumanUser talk:Human 19:19, 6 March 2010 (UTC)

Do any of these people matter?[edit]

Can someone who knows what they're doing review this webpage: (talk) 03:18, 21 November 2014 (UTC)

A few actual neuroscientists amongst a whole lot of unrelated fields - David Gerard (talk) 17:22, 16 April 2015 (UTC)

PZ on cryonicists again[edit]

[1] - includes comment from cryobiologist who apparently talks about this at length in a podcast (no transcript).

Also: A lot of the reference links here have gone stale and need refreshing - David Gerard (talk) 17:21, 16 April 2015 (UTC)

need to expand on the rabbit kidney[edit]

Cryonics advocates LOVE the rabbit kidney example. Here's a paper: [2] The nine days "surviving" rabbit showed plenty of signs of kidney failure (despite claims the rabbit could have survived indefinitely); they killed it and dissected it and found the kidney was way messed up, probably by cracks from freezing. This was a tiny object frozen with a best-case protocol. Apparently there's a case with a 45 days surviving rabbit? - David Gerard (talk) 09:13, 9 September 2015 (UTC)

new source[edit]

[3] - David Gerard (talk) 08:21, 16 September 2015 (UTC)

Preserving neurons. 99% won't cut it... or will it?[edit]

Having 'worked with stroke victims', the figure used for neuron loss following a severe stroke of "about 1%" sounds too low. Large mature strokes are usually pretty obvious on CT or MRI (as in "oh dear, there is a big hole where your temporal lobe used to be") which suggests volume loss more than 1%. I've checked the citations used currently (two blog posts and an article in the journal Stroke). I think the data is being misinterpreted.

The data is mainly in the Stroke article (Time Is Brain—Quantified. Saver JL. Stroke 2006; 37: 263-266). Saver analyzed the literature to determine "The typical final volume of large vessel, supratentorial ischemic stroke". (NB. a large vessel stroke is different from a large stroke). The answer is 54ml (findings ranging from 19 to 138ml). The total volume of the supratentorial brain quoted in the paper is 1020ml (excluding CSF). So the typical supratentorial brain loss is ~5% with some patients losing more than 10%! To be fair, size is probably less important than location e.g. a small stroke in the brainstem could stop you breathing; a large occipital stroke could blind you but leave other functions intact.

The total neuron count in the human brain is ~130 billion. However, surprisingly, most of them are in the cerebellum. The split (quoted in the paper) is 109 billion in the cerebellum to 21.5 in the neocortex (neocortex = 86% of supratentorial brain volume). The Wikipedia cerebellum article agrees with a 3.6:1 ratio [so it must be true...]. Presumably this reflects different architectures, glial numbers, white matter tracts, etc.

The Saver paper only looked at supratentorial strokes (i.e. not including the cerebellum). The total brain neuron count is skewed by the disproportionately large number of neurons in the cerebellum. Therefore using the total brain neuron count as the denominator for calculating %loss is misleading. I'm going to revise the 'Preserving neurons' section to better reflect the Saver paper data. Pantrog (talk) 01:12, 17 June 2016 (UTC)

I wrote that years ago and recall looking up the numbers ... if you have better cites, go for it - David Gerard (talk) 13:47, 17 June 2016 (UTC)

/r/ELI5 thread, includes an extensive writeup on the history and science of cryonics[edit]

We can probs crib some of this. The FCP Foundation (talk/stalk) 15:21, 19 November 2016 (UTC)

The article seems a bit harsh.[edit]

The people and organizations involved in cryonics are not cranks and charlatans promising that frozen people will wake up in a future of flying cars. They acknowledge that the frozen corpses are probably irretrievably dead but figure that a small chance of revival is better than the no-chance of burial or cremation. The article makes it sound like they are as bad as Sylvia Browne going up to desperate grieving parents and offering to let them talk to their dead child for 20 minutes in exchange for 700.00 U$D when the cyonicists themselves admit that it is an extreme gamble, not likely to work. The article makes it seem like cryonicists are out-and-out con artists, selling immortality when this is not true. — Unsigned, by: / talk / contribs

On talk pages, please sign your comments using four tildes (~~~~) or by clicking on the sign button: SigButt.png on the toolbar above the edit panel. (You can indent successive talk page comments using one more colon (:) for each line.) Thank you. Christopher (talk) 10:29, 19 March 2017 (UTC)
That argument is addressed in the article. It deals with it pretty well I think. Christopher (talk) 10:38, 19 March 2017 (UTC)
'Small chance'? Once 'your yourness' (personality, soul etc) has left your body how is it possible to 'get it back in there'? And who would want to be revived as a very sick/old/damaged person (which is what most of the cryonicised persons are)? The most that could probably be done is creating a clone (which does work, if poorly) - for which 'a suitable tissue sample' would suffice (and be much cheaper to store). (talk) 11:37, 19 March 2017 (UTC)
There is a small chance in that nothing is ever 100% certain (which I think is trivial, it's not certain there isn't an Invisible Pink Unicorn in the room but I happily assume there isn't). Also, a soul? There's no evidence for a soul or anything of that sort. Your personality is encoded in your brain. Christopher (talk) 11:45, 19 March 2017 (UTC)
They acknowledge that the frozen corpses are probably irretrievably dead They do a lot of not acknowledging this, actually.
The article makes it sound like they are as bad as Sylvia Browne going up to desperate grieving parents and offering to let them talk to their dead child for 20 minutes Reread the bits on Kim Suozzi, you've correctly assessed them there - David Gerard (talk) 14:34, 19 March 2017 (UTC)
I was catering for all preferences. We all know that we have 'a your-ness' (and most of us assume that others do as well) - but some people call their 'your-ness' a soul).
And when the energy sources run out, the cryogenics set ups will go pretty early. (talk) 22:47, 19 March 2017 (UTC)

Possible breakthrough for cryopreservation.[edit]

I'm thinking about adding this to the article to address some of the 'holes' in cryonics, at least as a possible starting approach for unfreezing people. Basically before an organ is frozen it is surrounded by metallic nanoparticles that will react to electromagnetic fields. When the organ needs to be unfrozen it is placed in a chamber where these fields are generated by coils and the heat is then evenly distributed throughout the organ. Preventing the formation of ice crystals and damage. I admit to not having an adequate background with this sort of thing but it is something to vet for the article. Recent version can be found on the verge.--That Imbecile (talk) 06:05, 2 July 2017 (UTC)

Interesting (speculatively) and relevant for the article, absolutely. Whatever the cryo people are up to is relevant to our coverage of it. That being said, cryonics still has a long way to go in practice before it could reasonably be called anyting more than a 'pipe dream' of sorts. And stuff like thisWikipedia will hardly cease to be relevant to the whole discussion. Reverend Black Percy (talk) 13:16, 2 July 2017 (UTC)
It seems to me that this would just replace the problem of ice crystals forming in the brain matter with the problem of every neuron being impregnated with foreign, conductive nano-particles. You might not get a grey slushie, but I'd think that there would still be considerable damage; manifesting as sustained epilepsy, perhaps. Daev (talk) 14:22, 3 July 2017 (UTC)
When all is said and done with cryonics #Elvis has left the building/the mustard jar is empty#. (talk) 15:55, 3 July 2017 (UTC)


You cannot by cryonised until 'that which sits behind the eyeballs' has left the skull.

How will the cryonicisers locate 'the eyeball-mover' and, having defrosted the body (or created BodyMark2) shove it back in? Anna Livia (talk) 18:09, 9 April 2019 (UTC)

Questionable quality of references cited[edit]

Reference #14 is just an anonymous Internet comment from an unverified source. That is not good.

The site is cited a few times, but the trustworthiness of this site feels dubious.

Professormagic (talk) 10:39, 26 June 2019 (UTC)

Your attempts to shit up the intro with special pleading are probably unsuitable for a cover article - David Gerard (talk) 11:23, 26 June 2019 (UTC)


This is often referred to in the media as "cryogenics". Should the article say a bit more about that confusion? Also should cryogenics redirect here? --Annanoon (talk) 09:11, 19 August 2019 (UTC)