X-Message-Number: 4718 From: Eugen Leitl <> Newsgroups: sci.cryonics Subject: Re: Freezing living brain as opposed to dead brain Date: Thu, 3 Aug 1995 16:31:07 +0200 Message-ID: <> References: <3uskqc$> <3vhnkg$> <3voo69$> On 2 Aug 1995, Brian Wowk wrote: > In <3vhnkg$> (GeorgeNet) writes: > [ some crudish uploading ] > This read-your-brain-into-a-computer-and-become-immortal-in- > your-natural-lifetime meme seems to be acquiring the status of an > Urban Legend. Where is this idea coming from? William Gibson novels? Marvin Minsky. Hans Moravec. Lots of others. One's own common sense. (But please without that -become-immortal-in-your-natural-lifetime nonsense). > I'm beginning to fear that it might be like astrology; an insidiously > destructive meme that no amount of reason will overcome. Cryopatient nanoressurection is just another such destructive meme. Without nanotech, mainstream cryonics is a hollow promise. > What we have here is a classic example of Occam's Razor. > Q: What is the best way to get the information contained in your > brain into the future? A: TAKE YOUR BRAIN WITH YOU into the future. Of course. What other alternative do we have, now? > What mental block is it that causes some poeple to respond with, > "Read the contents of your brain into a computer (using some > non-existent technology of unspecified lossiness), and then give > your brain to a funeral director for prompt incineration (implied, > but not usually stated). Ah. You misunderstood. There isn't any such technology, this is the precise reason why uploader sign up or plan to sign up for neurosuspension or full suspenion. We rely on the possibility that such scanning technology and the appropriate dedicated neuroaccelerator hardware becomes available in the future, 100-200 years from now. There is no way how we could survive such time spans in person, hence we have to sign up. Even if we had the scanning technology of sufficient resolution, we would not know what aspects of raw data are relevant and which not. Even if we knew, the magnetic or optical media costs would be huge and media would have to be recopied each decade or so to counteract deterioration. Media cost alone will surpass any running costs for liquid nitrogen. > Look at it this way. A cryopreserved brain contains > some 10^27 bits of information (about the same as a living I wish I knew how you arrived at that figure. Straightforward calculation seem to indicate that's more like 10^16 bits. A _slightly_ smaller amount. > brain; today's best cryonics procedures achieve *excellent* > structural preservation, from the molecular level on up.) Of course. We can preserve a snapshot (admittedly, with artefacts) of entire brain. What can we hope more, today? > By comparison, the best medical imaging technologies available > today (high resolution MRI) capture about 10^8 bits of brain > information. Do you really want to travel into the future > losing 10^19 marbles along the way? MRI is intrinsically flawed since we need a critical number of nuclei to get a signal. There _is_ MRI microscopy, but resolution is about 1x1x100 um for small specimens (insects/mice) due to field gradient trouble. This is about the end of the line: one cannot achieve much better resolution with MRI. There is no nondestructive scanning technique I currently am aware of for physical reasons. > Nor are things likely to get any better soon. To > capture all the subtle details of memory, personality, > and identity you must resolve not only neurons, but also > synapses, and *molecular contents* of synapses. Imaging Cell type, connectivity and synapse type/strength. Yes. > technologies capable of this are not going to be realized > in the natural lifetime of anyone reading this message. I think you are wrong. We could have abrasive AFM imagining even now (currently, they use vacuum sublimation) and possibly we could have such scanning in 5-10 years from now. Unfortunately, the amount of raw data is literally overwhelming. Essential feature extractor is necessary. But we don't know what essential features are yet. Even if we knew, there won't be the neurohardware available much earlier than 100 years. But trust me, uploading will come earlier than cryoressurection, since it does need full-fledged nanotechnology, the absolute prereqisite of mainstream cryonics. > In fact, it is extremely unlikely that the kind of data > gathering required for a brain upload will ever be achieved > non-invasively. It is far more likely that advanced _very_ I would even say nondestructive scan is impossible. > in-situ nanodevices will be required-- the kind that the > *22nd* century (not the 21st) will bring. They would be nice, but not actually necessary. > The post I am replying to began by questioning > "the problems of chemical freezing and thawing of biological > tissues." It is important that we keep in perspective > what these problems are. Cryonics already preserves a > level of structural and molecular information that no > imaging technology will match for another 100 years. Very true. Unless we can capture all atomic positions with 100 pm relative resolution. > The remaining problems concern subtle chemical effects > like cryoprotectant toxicities, and cooling/rewarming > rates that affect our ability to retrieve brains in > *perfect* (functionally viable) condition. By the standards > of what imaging technology can do (or will be able to > do for the foreseeable future), cryonics is already damn > close to perfect. It is this fact which troubles me mightily. There won't be too much progress in future. I wish I knew the extent of vitrification artefacts and information lossage on neural tissue. > Don't get me wrong. I think that uploading (like > star travel) will happen, and that it will be a very important > part of humanity's future. But also like star travel, don't > expect to see it tomorrow. And certainly don't expect it > to save your life if you are living today. Of course. Currently, there is no alternative to cryonics and, even more important, these alternatives are unlikely to emerge. Currently, the way to uploading paradise leads straight through the cryotomb (and is paved with legal advice and insurance bills). -- Eugene > Brian Wowk > MR Technology Group > Institute for Biodiagnostics > National Research Council of Canada > > and > > President > CryoCare Foundation > > (Probably the world's only expert on both scanning brains AND freezing them.) There isn't any scanning expert, some few neuroscientists maybe. That your real name is Dr. Frankenstein we all know, Brian ;) -- Eugene Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=4718