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There are a lot of steps that all need to go correctly for cryonics to work. People who had gone through the potential problems, assigning probabilities, had come up with odds of success between 1:4 and 1:435. About a year ago I went through and collected estimates, finding other people's and making my own. I've been maintaining these in a googledoc.
Yesterday, on the bus back from the NYC mega-meetup with a group of people from the Cambridge LessWrong meetup, I got more people to give estimates for these probabilities. We started with my potential problems, I explained the model and how independence works in it . For each question everyone decided on their own answer and then we went around and shared our answers (to reduce anchoring). Because there's still going to be some people adjusting to others based on their answers I tried to randomize the order in which I asked people their estimates. My notes are here. 
The questions were:
- You die suddenly or in a circumstance where you would not be able to be frozen in time.
- You die of something where the brain is degraded at death.
- You die in a hospital that refuses access to you by the cryonics people.
- After death your relatives reject your wishes and don't let the cryonics people freeze you.
- Some law is passed that prohibits cryonics before you die.
- The cryonics people make a mistake in freezing you.
- Not all of what makes you you is encoded in the physical state of the brain (or whatever you would have preserved).
- The current cryonics process is insufficient to preserve everything (even when perfectly executed).
- All people die (existential risks).
- Society falls apart (global catastrophic non-existential risks).
- Some time after you die cryonics is outlawed.
- All cryonics companies go out of business.
- The cryonics company you chose goes out of business.
- Your cryonics company screws something up and you are defrosted.
- It is impossible to extract all the information preserved in the frozen brain.
- The technology is never developed to extract the information.
- No one is interested in your brain's information.
- It is too expensive to extract your brain's information.
- Reviving people in simulation is impossible.
- The technology is never developed to run people in simulation.
- Running people in simulation is outlawed.
- No one is interested running you in simulation.
- It is too expensive to run you in simulation.
To see people's detailed responses have a look at the googledoc, but bottom line numbers were:
|person||chance of failure||odds of success|
(These are all rounded, but one of the two should have enough resolution for each person.)
The most significant way my estimate differs from others turned out to be for "the current cryonics process is insufficient to preserve everything". On that question alone we have:
|person||chance of failure|
My estimate for this used to be more positive, but it was significantly brought down by reading this lesswrong comment:
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.
In the responses to their comment they go into more detail.
Should I be giving this information this much weight? "many aspects of synaptic strength and connectivity are irretrievably lost as soon as the synaptic membrane gets distorted" seems critical.
Other questions on which I was substantially more pessimistic than others were "all cryonics companies go out of business", "the technology is never developed to extract the information", "no one is interested in your brain's information", and "it is too expensive to extract your brain's information".
I also posted this on my blog
 Specifically, each question is asking you "the chance that X happens and this keeps you from being revived, assuming that all of the previous steps all succeeded". So if both A and B would keep you from being successfully revived, and I ask them in that order, but you think they're basically the same question, then A basically only A gets a probability while B gets 0 or close to it (because B is technically "B given not-A")./p>
 For some reason I was writing ".000000001" when people said "impossible". For the purposes of this model '0' is fine, and that's what I put on the googledoc.
At the end of CFAR's July Rationality Minicamp, we had a party with people from the LW/SIAI/CFAR community in the San Francisco Bay area. During this party, I had a conversation with the girlfriend of a participant in a previous minicamp, who was not signed up for cryonics (her boyfriend was). The conversation went like this:
me: So, you know what cryonics is?
me: And you think it's a good idea?
me: And you are not signed up yet?
me: And you would like to be?
me: Wait a minute while I get my laptop.
And I got my laptop, pointed my browser at Rudi Hoffman's quote request form1, and said, "Here, fill out this form". And she did.
Though cryonics has been practiced for forty years, its techniques have improved only slowly; its few customers can only induce a tiny research effort. The much larger brain research community, in contrast, has been rapidly improving their ways to do fast cheap detailed 3D brain scans, and to prepare samples for such scans. You see, brain researchers need ways to stop brain samples from changing, and to be strong against scanning disruptions, just so they can study brain samples at their leisure.
Most people, given the option to halt aging and continue in good heath for centuries, would. Anti-aging research is popular, but medicine is only minimally increasing lifespan for healthy adults. You, I, and everyone we know have bodies that are incredibly unlikely to make it past 120. They're just not built to last.
But what are you, really? Your personality, your memories, they don't leave you when you lose a leg. Lose most parts of your body and you're still you. Lose your brain and that's it.  You are a pattern, instantiated in the neurons of your brain. That pattern is sustained by your body, growing and changing as you learn and experience the world. Your body supports you for years, but it deteriorates and eventually isn't up to the task any more. Is that 'game over'?
Perhaps we could scan people's brains at extremely high detail so we could run them in some sort of human emulator. This requires a thorough understanding of the brain, huge amounts of storage, unbelievably fast computers, and very detailed scanning. If it's even possible, it may be several hundred years away.
Our bodies aren't going to last that long, but what if we could figure out how to preserve our brains so that the information didn't decay? Then, if the future turned out to be one in which we had advanced brain emulation and scanning technology, we could be revived. I don't know if people in the future would want to spend the time or money to revive us, but in a future with technology this advanced, reviving a preserved brain as a computer simulation could be really cheap.
The most advanced technology for long-term tissue preservation today  is cryonics: freezing with vitrification. You add something to the blood that keeps ice crystals from forming and then freeze it. This is pretty much the same thing frogs do, hibernating frozen through the winter. The biggest organs that have been successfully brought back to working order after vitrification are rabbit kidneys, and the brain is a lot bigger and much more complex. While there are people applying this technique to human brains after death, it's very much a one way street; we can't revive them with current technology.
How much should it worry us that we can't reverse this freezing process? If we're already talking about revival via high-detail scanning and emulation, which is only practical after hundreds of years of technological development, does it matter that we can't currently reverse it? The real question in determining whether vitrification is sufficient is whether we're preserving all the information in your brain. If something critical is missing, or if something about our current freezing process loses information, the brains we think are properly preserved might be damaged or deteriorated beyond repair. Without a round trip test where we freeze and then revive a brain, we don't know whether what we're doing will work.
Another issue is that once you've frozen the brain you need to keep it cold for a few centuries at least. Liquid nitrogen is pretty cheap, but providing it constantly over such a long time is hard. Organizations fall apart: very few stay in business for even 100 years, and those that do often have departed from their original missions. Current cryonics organizations seem no different from others, with financial difficulties and imperfect management, so I don't think 200+ years of full functioning is very likely.
Even if nothing goes wrong with the organization itself, will our society last that long? Nuclear war, 'ordinary' war, bioterrorism, global warming, plagues, and future technologies all pose major risks. Even if these don't kill everyone, they might disrupt the cryonics organizations or stop technological development such that revival technology is never developed.
Taking all these potential problems and risks into account, it's unlikely that you can get around death by signing up for cryonics. In attempts to calculate overall odds for success from estimated chances of each step I've seen various numbers: 1:3, 1:4, 1:7, 1:15 and 1:400. I'm even more pessimistic: I calculated 1:600 when I first posted to lesswrong and have since revised down to 1:1000. To some people the probability doesn't matter, but because it's expensive and there are plenty of other things one can do with money, I don't think it's obviously the sensible thing to do.
(I also posted this on my blog.)
 Well, lose your heart and you're gone too. Except that we can make mechanical hearts and you stay the same person on receiving one. Not so much with a mechanical brain.
 Plastination is also an option, but it's not yet to a point where we can do it on even a mouse brain.
Summary: medical progress has been much slower than even recently predicted.
In the February and March 1988 issues of Cryonics, Mike Darwin (Wikipedia/LessWrong) and Steve Harris published a two-part article “The Future of Medicine” attempting to forecast the medical state of the art for 2008. Darwin has republished it on the New_Cryonet email list.
Darwin is a pretty savvy forecaster (who you will remember correctly predicting in 1981 in “The High Cost of Cryonics”/part 2 ALCOR’s recent troubles with grandfathering), so given my standing interests in tracking predictions, I read it with great interest; but they still blew most of them, and not the ones we would prefer them to’ve.
The full essay is ~10k words, so I will excerpt roughly half of it below; feel free to skip to the reactions section and other links.
From Mike Darwn's Chronopause, an essay titled "Would You Like Another Plate of This?", discussing people's attitudes to life:
The most important, the most obvious and the most factual reason why cryonics is not more widely accepted is that it fails the “credibility sniff test” in that it makes many critical assumptions which may not be correct...In other words, cryonics is not proven. That is a plenty valid reason for rejecting any costly procedure; dying people do this kind of thing every day for medical procedures which are proven, but which have a very low rate of success and (or) a very high misery quotient. Some (few) people have survived metastatic head/neck cancer – the film critic Roger Ebert, is an example (Figure 1). However, the vast majority of patients who undergo radical neck surgery for cancer die anyway. For the kind and extent of cancer Ebert had, the long term survival rate (>5 years) is ~5% following radical neck dissection and ancillary therapy: usually radiation and chemotherapy. This is thus a proven procedure – it works – and yet the vast majority of patients refuse it.
I recently got sparked by both Eliezer's post on Cryonics(http://lesswrong.com/lw/qx/timeless_identity/) and lsparrish's post on the economies of scale(http://lesswrong.com/lw/2f5/cryonics_wants_to_be_big/) that go in to cryonics, to do some actual research. Unfortunately, while both authors are happy to assert that there are "economies of scale" at work, there doesn't seem to actually be any published research on the matter. If I happen to be wrong, and someone else has more accurate numbers, I'll be pleasantly surprised to see myself corrected :)
Alcor Costs as of 1990 (http://www.alcor.org/Library/html/CostOfCryonicsTables.txt) seems like a reasonably reliable source of information. I'll be using them primarily because they were the only institute I could find that actually provides a break-down of their costs. The accompany article(http://www.alcor.org/Library/html/CostOfCryonics.html) suggests that the labor rates and equipment markups are actually excessively optimistic, but it gives a simple cost of $18,908.76 for neurosuspension (not whole body). Maintenance costs are given as $66.08 annually, which would require a $6600 investment to yield suitable interest. Call it $25K total.
Now, figuring out how economies of scale will affect this is tricky. I'll go ahead and run two estimates, but they're both reasonably crude. I'm trying to be optimistic in my math, because my starting premise is "cryonics is not financially viable, even with economies of scale", and I don't want my numbers to favour my starting hypothesis. It's also worth noting that I am assuming that the major cryonics facilities are already taking advantage of some economies of scale: it is quite true that one can get a 90% discount on liquid nitrogen, if you start at the price that someone would pay for a liter for personal usage; it is far less likely that a business that already dropped it's prices from $0.50/L to $0.13/L  can still claim a 90% savings by sufficient economies of scale.
There was recently a proposal that we should create YouTube commercials for cryonics. This is an area where the cryonics community is sorely lacking fresh content, and which in my opinion has higher leverage per unit effort relative to other kinds of content, for making the kinds of cultural changes that need to be made for cryonics to gain acceptance.
One beat procrastination,o
To get things started, I am offering the nominal sum of 10 bitcoins1 as a prize to whoever creates the the most "liked" promotional or educational video for cryonics on YouTube for the month of May, 2011. If anyone wishes to contribute to the prize and thus increase its size, send bitcoins here: <removed>
All funds sent to the above address will be transferred to the address of the person whose YouTube video promoting cryonics receives the most "likes" on YouTube during the month of May. Donors who let me know that they have donated will be given credit for donating below.
- Start date: May 1, 2011 at 12:00 AM GMT. Entry video cannot have been released on YouTube sooner than this.
- End date: June 1, 2011 at 12:00 AM GMT. This is when the votes (likes) will be tallied and the prize awarded.
- Video must promote cryonics and/or answer common questions about cryonics.
- Multiple submissions per person are allowed and encouraged, as are collaborations2.
- Xtranormal videos, slide shows, stick figure cartoons, voice-overs, and anything else that can go in a YouTube video are acceptable.
- Winner must have or obtain a bitcoin address3, and must let us know what it is along with a link to their video (which must be posted to YouTube) in the comments section of this post.
- In the event that there are multiple videos with substantially similar numbers of likes (to within 1% of the top number) at midnight of June first, they will all be treated as co-winners and receive equal shares of the prize.
Anyone who wants to donate to non-winning entries that they liked is welcome to do so as well (the bitcoin address of each entry will be visible below).
Let the games begin!
- These are a digital commodity that I thought would make a more fun and interesting prize than dollars, and seem to have a positive reputation on LW so far. It is also easy for me to keep track of. Market value was about $4 per bitcoin as of April 31.
- One bitcoin address per video please. Teams are responsible for divvying up the prize money among members.
- The simple way is to create an account on MyBitcoin. You can also install the Bitcoin client.
Current prize fund (to be updated): 14.75 BTC (103.29 USD @ 7.003)
Donors known so far:
There will be a meetup for Southern California this Sunday, January 23, 2011 at 4PM and running for three to five hours. The meetup is happening at Marco's Trattoria. The address is:
If all the people (including guests and high end group estimates) show up we'll be at the limit of the space with 24 attendees. Previous meetups had room for walk-ins and future meetups should as well, but this one is full. If you didn't RSVP in time for this one but want to get an email reminder when the February meetup is scheduled send me a PM with contact info.
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