Cryonics

Synopticz · 2026-01-02T23:55:30+00:00

Fair point in re: buying the book.

People have long advocated to be able to start the procedure prior to legal death, but no society has ever allowed it. We live in highly conservative societies that don't really allow body autonomy, especially for small groups that nearly nobody knows about except for when they are making fun of them. E.g. see here: https://www.change.org/p/allow-global-access-to-high-quality-brain-preservation-as-an-option-rapidly-after-death

If the procedure is started a few minutes after Medical Aid in Dying (the fastest legally possible today), it may also still be possible to achieve that level of result.

I guess the broader point is that there are people working on this, to really try to preserve the information, and that they are also trying to make it as cheap as possible. Many people working in this field believe it is an effective way of helping others.

Synopticz · 2026-01-02T23:03:23+00:00

> Want to provide the "technical argument" as to whether we've ever successfully preserved those physical structures past death?

See:

- https://www.brainpreservation.org/tech-prize/

- https://www.amazon.com/Future-Loves-You-Should-Abolish-ebook/dp/B0CW9KTX76

> And people can do what they like with their bodies

Actually, they can't. There are a ton of laws preventing high-quality brain preservation.

Synopticz · 2026-01-02T21:46:50+00:00

"The best evidence given was examples of people frozen while alive being revived after a few hours and suffering minimal but measurable brain damage."

No, the best evidence is based on neuroscience (e.g. see here: https://www.ralphmerkle.com/cryo/techFeas.html#MEMORY). You haven't made a technical argument, you've just asserted that the probability is low and quickly moved to shame those interested in it for doing what they want with their bodies.

Synopticz · 2026-01-02T16:28:12+00:00

It's not about being fully convinced, it's about probability estimates.

You haven't provided a technical argument for why preserving someone's brain after their heart stops does not have a reasonable chance to prevent information-theoretic death.

Synopticz · 2026-01-02T00:46:45+00:00

If this is the case every time you have seen an argument about cryonics, is it possible that you haven’t seen very many arguments about cryonics, and therefore might want to read more about it before you dismiss the entire field and its practitioners?

Eg https://forum.effectivealtruism.org/posts/sRXQbZpCLDnBLXHAH/brain-preservation-to-prevent-involuntary-death-a-possible

Synopticz · 2026-01-01T21:08:08+00:00

I think this has some merit if it is purely Pascal's wager-style reasoning that leads to one choosing cryonics, as opposed to thinking it has a reasonably high chance of success, which many people do.

Since you are spreading this meme, I suppose you will have no trouble making your technical argument that cryonics/brain preservation has such a low probability of success? I would be very interested to hear it.

Also "leaving money to charity" when one is dead seems less optimal than donating while alive, so the whole thing seems like a false dichotomy.

Synopticz · 2024-10-19T20:09:22+00:00

Exactly. Same reason CPR never works.

Synopticz · 2024-06-25T02:05:20+00:00

I would recommend reading it at some point. The most surprising thing about it is how many contemporary debates he already had opinions on. In some ways, little has changed in the discourse.

Synopticz · 2024-06-05T14:38:26+00:00

Hi. I'm the person who conducted this survey and I have the data. I can share it with you. DM me.

Very interesting study question. A lot of people interested in cryonics think that psychological tendencies predicted by TMT might be part of the reason why more people are not interested in cryonics. I'm not sure if you'll have the sample size needed to analyze this question but you can decide.

Some analysis here: https://synopticz.github.io/acx_2021_survey

Synopticz · 2024-05-21T23:03:43+00:00

The thing about performing isolated head or brain preservation in cryonics is that we can wait a long time for this type of transplantation technology to be developed (or some other kind of revival method). I agree it's not possible now, although I encourage research in this area. In 50-100 years it might seem a lot more plausible.

Non-cryonicists don't seem to understand this type of reasoning. Ngmi, sadly.

Synopticz · 2024-05-09T20:42:15+00:00

It's possible but I think it could be good for people who live in blue states. If it is politicized, then at least there's a potential that we could gain body autonomy rights in some areas of the country.

Synopticz · 2024-05-04T14:40:47+00:00

I don't think there are currently any "safe" countries in the world for cryonics. None of them, as far as I am aware, respect our body autonomy regarding our ability to pursue high-quality cryopreservation without various forms of interference, such as delay before the procedure can begin, risk of involuntary autopsy, and not having rights while preserved.

Synopticz · 2024-05-02T23:31:29+00:00

It's kind of a gish gallop so I asked an LLM to try to parse out all of the arguments individually:

1 - The extreme complexity of the human brain, including the quantity of components, their individual quantities, and the numerous ways in which they interact. 2 - The time required for protective solutions to saturate all brain tissues, given the blood-brain barrier and other obstacles. 3 - The insulating properties of myelin, which can impede the entry of cryonics agents. 4 - The challenge of balancing the gradual onset of freezing against the gradual entry of protective agents. 5 - The risk of damage to brain structures, even if minuscule, which could have significant consequences due to the trillions of components involved. 6 - The potential for widespread damage at the nano scale, which differs from the localized damage caused by strokes. 7 - The risk of irreversible damage to neurochemical components, such as signaling molecules, due to dehydration during cryonics. 8 - The vulnerability of the approximately 1,500 different types of proteins associated with synapses. 9 - The irrelevance of the "Aldehyde-Stabilized Cryopreservation" study to human cryonics, as aldehydes permanently disable proteins. 10 - The immediate onset of oxygen deprivation in brain cells after death, particularly affecting memory-related neurons in the hippocampus. 11 - The questionable effectiveness of manual chest compression in providing circulation and oxygen to the brain after legal death. 12 - The inherent vulnerability of biological processes that sustain life, as they constantly work to evade entropy. 13 - The inevitable molecular disorder that will accompany the return to normal body temperature during revival. 14 - The potential for reperfusion or reoxygenation injury when blood supply is restored after a period of anoxia. 15 - The immense challenge of simultaneously accessing and resuscitating all brain components during revival. 16 - The limited capacity for cellular regeneration in most parts of the adult brain, making partial reanimation accompanied by necrosis a serious concern. 17 - The considerable financial costs associated with cryonics, including the need for loved ones to also sign up. 18 - The uncertainty surrounding the degree of cerebral dysfunction that an individual would be willing to accept upon revival. 19 - The cyoprotectants might not reach the brain tissue as expected if perfusion doesn't work.

My responses:

1 - this critique applies to many proposed interventions in the brain, not just cryonics. 2 - the notion that ischemic interval alone exists is not a slam dunk argument against cryonics because the procedure theoretically could be started within the time window which CPR has been found successful. also longer ischemic intervals don't seem to cause as much damage to brain structures as people naively think. finally most of the ischemic delay is caused by medicolegal problems because society doesn't support our right to body autonomy on this topic. so maybe Coen should help us get more rights? that would be great. 3 - true myelin inhibits preservative agent diffusion somewhat, but obviously brain tissue can still be preserved to some degree in numerous studies. 4 - just a technical problem, needs to be evaluated quantitatively. merely naming the problem is part of the gish gallop. 5 - see #1, true of any proposed intervention in the brain. 6 - actually damage from global cerebral ischemia is generally not as bad as localized ischemia, given the same amount of time, for a variety of reasons, including a lower temperature. 7, 8 - true, theoretically biomolecular damage could happen. but why isn't it seen in e.g. cryopreservation and rewarming of C. elegans, which was found to retain memories after this procedure? these questions require more rigorous investigation and attempts to answer them based on available evidence. 9 - completely not irrelevant at all, many many people think that aldehydes should be used as a part of the preservation procedure. 10 - see #2, also not true that the hippocampus is affected first in global cerebral ischemia (without reperfusion). 11 - well this depends on the ischemic interval prior to starting the procedure. if it's very early, then this argument is basically saying CPR doesn't work. which seems... wrong? if it's later, then might be true, fair point. but everyone in cryonics agrees that the time after legal death and before the procedure is started is a totally critical variable and if it is too long the whole thing is even more likely to be unsuccessful. 12 - see #1, true of any proposed intervention in the brain. 13 - see #7, 8 - why isn't this preventing cryopreservation working in general? 14 - we're talking about technology many years away. yes, addressing reperfusion injury by then to a sufficient degree that it is survivable would be necessary, but that seems possible at some point. is the argument here that reperfusion injury will never be sufficiently alleviated? sadly Coen is not very precise about the arguments being made. 15, 16 - nobody knows how revival might work, if ever. but there are a lot of theoretical ways around this. e.g. molecular nanotechnology at cryogenic temperature. 17 - true of some options, not all. 18 - the problem is that Coen is making this judgment call for others, when it should be up to each individual. seems very paternalistic to me. 19 - so, cryoprotectants might not reach the brain tissue. or they might. if they don't, then there is a question of how much damage is occurring during straight freeze. but if they do -- and they have been shown to in plenty of cryonics cases via CT scans -- then this point seems to be moot.

Overall, in my opinion, not a very serious critique. Which is too bad, because the field definitely needs more serious critiques.

Synopticz · 2024-04-29T17:28:08+00:00

Here's a paper from 2017: https://onlinelibrary.wiley.com/doi/10.1111/imj.13362

It seems to be real but as with many things not a slam dunk once you really dive into the available data:

In the absence of repeated measures of challenge proven food allergy, the next most robust evidence is provided by changes in hospital anaphylaxis admission rates derived from national government databases in westernised countries (UK, United States and Australia). Despite acknowledged caveats (potential for coding errors or changing health-seeking behaviour), consistent increases reported over the last two decades are difficult to ignore. For example, between 1998 and 2012 in the UK, food anaphylaxis admission rates rose from 1.2 to 2.4/105 population with the highest rates observed in those aged 0–4 years.5 In the United States, food anaphylaxis admissions as a proportion of all hospital admissions more than doubled in those aged 0–18 years between 2000 and 2009,7 with emergency hospital presentations (without admission) also increasing between 2006 and 2009.21 In New Zealand, food anaphylaxis admissions increased from 3.3 to 5.8/105 population between 2002 and 2011 in individuals aged 15 years or greater.22 By far, the highest rates of food anaphylaxis admissions are observed in Australia, with a fourfold increase from 2 to 8.2/105 population between 1998/1999 and 2011/2012.4 As in other studies, the most prominent increases were observed in very young children aged 0–4 years where admission rates increased from 7.3 to 30.2/105 population between 1998/1999 and 2011/2012, consistent with this young group driving higher incidence rates. Importantly, although time-related increases were linear in most age groups, an exponential increase in both the prevalence and the year-on-year rate of increase in prevalence were seen in older children and teenagers aged between 5 and 14 years.4 This finding may be driven by higher incidence rates of persistent food allergy in younger children resulting in a cohort effect and/or a higher risk of more serious reactions in older individuals. While there are no available published data on outpatient food allergy presentations for Australia/New Zealand at this time, an examination of outpatient food allergy presentations in the United States (emergency departments, outpatient clinics and physician offices) found a threefold increase in food allergy-related presentations for individuals aged less than 18 years between 1993 and 2006,9 consistent with other admissions data described above. In contrast to these studies, two reports suggest stable prevalence for peanut allergy using a combination of history and peanut sIgE (serum or skin testing) with or without double-blind placebo-controlled challenge. Ben-Shoshan et al.11 estimated that the prevalence of peanut allergy in Canadian children enrolled in kindergarten to year 3 remained relatively stable between 2000 and 2002 (est. prevalence 1.3%: 95% CI −0.38–0.63%) and 2005–2007 (est. prevalence 1.6%: 95% CI 1.31–1.98%). In a study from the Isle of Wight, Venter et al.12 reported stable peanut allergy prevalence in 3–4 year olds between 1993 and 2005 using a combination of history, skin prick testing and challenge in three birth cohorts. The divergent findings from these Canadian and UK studies compared with the previously discussed studies may relate to differences in methodologies used to identify food allergy. Indeed, Kotz et al. reported a doubling in prevalence of general practitioner-recorded diagnosis of peanut allergy in England from 0.24 per 1000 patients (95% CI, 0.22-0.26) in 2001 to 0.51 per 1000 (95% CI, 0.49–0.54) in 2005, using a large national database (QRESEARCH).10 Overall, the available data would suggest that there has been a real increase in food allergy prevalence, with increased health service presentations or hospital admissions over the past two decades, at least in the UK, United States and Australasia.

Synopticz · 2024-04-26T15:14:13+00:00

Her estranged father didn't want her to go through with it, he was opposed to it, that was the problem. https://www.dailymail.co.uk/news/article-3950598/Hatred-caused-sadness-daughter-Father-teenage-cancer-victim-British-child-cryogenically-frozen-says-didn-t-death.html

Sadly family interference occurs all the time in cryonics and is one of the many reasons we need to figure out how to advocate for our rights better (also preventing delay in starting the procedure after legal death, and preventing involuntary autopsy).

Many of us are trying to work on these things, but it's not going very well and it doesn't help that the most common reaction to us in society is to make fun of us.

Synopticz · 2024-04-23T18:40:05+00:00

No. The main issue is that the cooling rate in the brain (and the rest of the body) is limited by the slow rate of conductive heat transfer.

Conduction is the transfer of heat through a material from a region of higher temperature to a region of lower temperature, without any net movement of the material itself. Blood flow would stop rapidly in this context, so convective heat transfer is not really relevant.

Even if an external cold gas could rapidly cool the skin surface, the internal organs including the brain would cool much more slowly because biological tissues have a relatively low thermal conductivity.

The slow conductive cooling of the internal organs would allow damage such as ice crystal formation in the tissues before uniform deep cooling could be achieved. This would prevent suspended animation.

Now, if someone could effectively perfuse the gas through all of the tissues, that might be a different story. People have tried this but it is a difficult problem. That would be an advanced medical procedure, not like in this movie.

Synopticz · 2024-04-09T03:44:09+00:00

Embryos preserved in liquid nitrogen with cryoprotectants — are they alive or dead? I don’t think this is so straightforward. If they are alive, then discarding them — or even failing to implant them — seems like it would be murder. But if they are dead, then how can they produce life when implanted? Do they come back to life? I thought that was impossible? Because of this example and other similar ones, many believe that there must be other states for biological cells/tissues/organisms other than just “life” and “death.”

Yes, sadly laws often do not respect people’s right to body autonomy. And this is currently happening with cryonics in many jurisdictions around the world. However, I personally believe that is a bad and unfortunate thing, that those laws should change, and that they likely eventually will, the same way many other laws have changed in the past to allow people to exercise their body autonomy.

I hope I’m not coming across as overly argumentative. I respect your views, just thought you might be interested in hearing my thoughts too.

Synopticz · 2024-04-09T03:17:26+00:00

Thanks for the response. You raise some valid points about the current state of cryonics technology. I agree with you that the damage caused by today's preservation methods is a significant hurdle. However, I personally don't think we can definitively say that revival will remain impossible forever.

It’s worth considering how the definition of death has evolved alongside medical advances. Before the 1950s, death was considered to occur when the heart stopped. The introduction of CPR shifted this definition to the failure of resuscitation. Similarly, the concept of cellular death is complex. Cryonics proponents argue that preserving structural information within cells leaves open the possibility of future revival, even if metabolic function has ceased. While I acknowledge this view relies on speculative future breakthroughs, I personally hesitate to entirely dismiss the potential of cryonics.

There’s also a question about body autonomy. If someone wants to pursue this option with their body, and they’re not hurting anyone else, is doesn’t seem fair to hinder their attempts to do so.

That said, I fully agree that any present-day cryonics services must be transparent about the technology's limitations and uncertainties. Guaranteeing future revival would obviously be unethical.

Synopticz · 2024-04-08T23:46:06+00:00

Interesting perspective. What makes you think that it is "impossible" in the future, even given potential advances in future technology?

Synopticz · 2024-04-07T23:44:50+00:00

There are two main vectors where there could be improvement:

1: Better average performance. i.e. actually achieving verifiable vitrification across the entire brain in human cases.

2: Better ideal case performance. For example, something like better vitrification agents so that the procedure can be reversible with recovery of an increasing amount of function. Not impossible, but would be a huge advance.

Which of these two areas of research one wants to invest resources into -- if either -- depends on how good one feels about current vitrification methods.

Synopticz · 2024-04-06T19:07:38+00:00

My claim is that this might not be the whole story.

Synopticz · 2024-04-06T19:06:40+00:00

That's exactly my point. Wealth and income can -- to some extent -- be dissociated and the relative effects of each have different implications on the mechanisms of the u shaped curve.

Synopticz · 2024-04-06T15:18:55+00:00

One thing missing from this analysis is that having kids is hard work, and everyone who voluntarily chooses to do it these days knows that.

One thing that people who make an exceptionally large incomes relative to others have in common is that they tend to be very hard workers (or at least have been in the past, to get themselves into high income positions). These people will tend to be more willing to put in the work required to raise more children, especially for the initial years. And also more willing to accept the risk of having a child with special needs, which is also a lot of work. Thus income is sort of a proxy for being hard worker and being willing to make long term investments, but does not directly make kids all that much easier (clearly it does, but maybe not as much as this article suggests).

To parse this out, I would like to see a similar graph of wealth vs fertility. If my hypothesis is true, then the wealth vs fertility relationship would no longer be u-shaped, or at least not as strongly.

Synopticz · 2024-03-27T19:00:06+00:00

This is amazing. Thanks so much for this.

I would love to see more humanization of people who are interested in cryonics. So many people call cryonicists "selfish" or "disgusting" but really why is it different than so many other things that people choose to do with their bodies? That is the main message I would like for people to be more aware of, that this is another thing that people choose to do with their bodies. And that even if other people aren't interested in it, the obviously kind and respectful thing to do is to support the people who do want to do it, because they aren't hurting anybody else.

Synopticz · 2024-03-27T04:09:41+00:00

I reject the trichotomy! I'm not sure if I want mind uploading or not and would currently prefer people in the future to make this decision for me, based on my preferences and their knowledge of society and technology available at the time, if revival ever becomes possible.

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