Cryonics

[ciphergoth]

I'm considering signing up with the Cryonics Institute. Are you signed up? I'd be interested to hear your reasons why or why not. It does of course sound crazy, but when you press past that initial reaction to find out why it's crazy, I haven't heard a really satisfactory argument yet, and I'm interested to hear what people think. There are many reasons it might not work, but are there reasons to think it's really unlikely to work? How likely does recovery need to be for it to be worth it?

Comments

[zotz]

"Will never return" is too high a standard to set. "Are very unlikely to return" I would subscribe to.

[ciphergoth.livejournal.com]

But is there no more detail available than this on why it's so unlikely? From what I've been able to find out, it's plausible to imagine that it might be as simple as serially slicing the brain open and scanning the surface with an SEM and various technologies to find out about the chemistry at the exposed surface, then doing a whole-brain-emulation on the result. Is there any part of that story that would be a big surprise given what we currently know about the brain?

I've no interest in throwing my money away on false hope. I really want to know.

[zotz]

It's not impossible that a more delicate and advanced version of that might be possible, but it's so far from what's currently possible as to be pie in the sky for all practical purposes, and there is no point getting involved in detailed discussions of crust compositions before we even understand the problem.

I don't think an answer is currently possible that would satisfy you. It's likely to be possible in principle, it might be possible in practice, but it's far enough in the future that I wouldn't trust any existing organisation (with the possible exception of the Catholic Church) to be around in a recognisable form to implement it for me.

[ciphergoth.livejournal.com]

Please tell me how I can find out more about why there is so much distance between where we are and where we would need to be!

[zotz]

As an example, using molecular dynamics to simulate organic macromolecules has only to date been used (with extreme difficulty) to model the smallest of protein molecules for periods of about a millisecond. Going by what I was told was the state of the art 20 years ago, I'd guess we're at least two centuries off (assuming Moore-style continuing advance, which is admittedly a major assumption) off being able to do this for a brain-size object even as a grand-challenge computing project.

And that, you will note, is simply assembling the computing power, and will at that point only allow one person to be simulated briefly and at an extremely slow pace. Whether it would be possible to construct such a model at that point depends on far less quantifiable factors. Whether microscopes will exist by then that can resolve not just locations of atoms but also their type and molecular associations, without disturbing those around and behind them enough to render the task futile, is as far as I can tell impossible to guess. Damaging your sample before you've found out all you want to know isn't usually a big problem in microscopy - you just try again with a different sample. In this case, not so easy.

I'm not really sure that approach would be any easier than repairing a dead brain, to be honest.

[djm4]

...it's plausible to imagine that it might be as simple as serially slicing the brain open and scanning the surface with an SEM and various technologies to find out about the chemistry at the exposed surface, then doing a whole-brain-emulation on the result.

Do you have a citation for that? It honestly looks more like Star Trek 'tech' than anything remotely plausible to me, and I'd be interested to know what advances in Scanning Electron Microscopy have happened without my knowledge or are envisaged that make that seem simple.

[ciphergoth.livejournal.com]

Lots of details here.

[djm4]

At first sight, I would describe that as a green ink PDF.

On Electron Microscopy, for example:

"How much of the functionally relevant information can be deduced from scanning in a particular modality (e.g. electron microscopy)? At present, electron microscopy appears to be the only scanning method that has the right resolution to reach synaptic connectivity, but it is limited in what chemical state information it can reveal. If it is possible to deduce the function of a neuron, synapse or other structure through image interpretation methods, then scanning would be far simpler than if this is not (in which case some form of hybrid method or entirely new scanning modality would have to be developed). This issue appears to form a potentially well‐defined research question that could be pursued. Answering it would require finding a suitable model system for which ground truth (the computational functionality of target system) was known, using the scanning modality to produce imagery and then testing out various forms of interpretation on the data."

You may translate that as 'it's plausible to imagine that EM can do this simply'. I would translate it as: 'EM's the only technology that could give us the resolution, and there is absolutely no way it can reveal the chemical state, nor is there any way of preparing a sample of organic tissue for EM that won't damage the very state you're trying to record. Charge build-up will be a real issue on a sample you don't make conductive (even with TEM), and making it conductive without masking the underlying detail you're searching for is probably impossible. It might be possible to overcome one of these limitations in the future, but nobody has a clue how to.'

Also, they're asking whether it's possible to deduce the 'function' of a neuron - even if that were possible, it's an altogether harder prospect to deduce the state of the neuron at the time of death, even if you know the function.

I find it difficult to imagine that that passage was written by anyone at all familiar with how EM works - it smacks of someone who thinks it's basically like optical microscopy with a bigger lens - and furthermore, in the twenty years since I first did any hands-on SEM and TEM, we've moved no closer to making brain scans with it a practical proposition (as far as I can tell from reading around Wikipedia).

[djm4]

(Not sure I'll have time to give a better answer than this one, though - I realise it's somewhat lacking - but it's just eaten me for almost an hour, and I can't let it continue to do so.)

[ciphergoth.livejournal.com]

Well I'm incredibly grateful for one of the most useful comments in the whole thread, so thanks very much for that hour of your time.

I'll probably make a series of posts about this each trying to get to the bottom of one the most common objections. I really hope they can attract more comments like that!

[djm4]

You're welcome.

You might want to find someone who's done actual Electron Microscopy since 1994, to check that my understanding is correct. ;-)

[ciphergoth.livejournal.com]

Not expecting you to follow up on this any time soon, but just for your interest I note that the sentence you quote is from the introductory part of the PDF. There's a much more detailed discussion of scanning technology starting on page 40.

[djm4]

Ah, thanks. That bit is written by someone who understands the technology (and IMO the introductory paragraph is a terrible summary of it), but I still wouldn't get your hopes up. As far as I can see, it offers no way to discern the state of the neurons, and admits that while it might be possible to get the structure for a small slice of the brain, getting it in 5nm detail for the whole volume is currently impossible, with no known way to overcome the current technological limitations. Many of those limitations are imposed by the wavelength of the medium you're scanning with, and there's just no easy way round that. The speed of scanning (which is also currently a showstopper for the ~5nm technologies that might otherwise be attractive) might be able to be improved, but bear in mind that you're working at levels where the energy of the electrons/photons that you're using to scan risk damaging the sample, and using more of them in parallel may damage it more. The data transfer/storage problem probably is solvable, by contrast.

I find it a bit worrying that the most promising technologies in the table on page 43 - SOM and SEM, especially combined with array tomography - have relatively little discussion in the text that I can see. This makes me suspect that they're only even superficially attractive because not enough is known about them to know they don't work.

Also, given that the conclusion says 'this sets a resolution requirement on the order of 5 nm at least in two directions,' there's far too much discussion of technologies that can only scan down to resolutions two orders of magnitude higher than this. So the text gives the optimistic prediction that '[KESM] enables the imaging of an entire macroscopic tissue volume such as a mouse brain in reasonable time', but what good is that given that KSEM only scans down to 300nm x 500nm? It's an obvious question, and I'd expect an honestly-written paper to answer it. Because this paper doesn't, I smell a rat (or, more likely, someone clutching at straws).

The discussion starts 'As this review shows, WBE on the neuronal/synaptic level requires relatively modest increases in microscopy resolution...' which may be technically true but vastly understates the difficulty of increasing the resolution of the techniques discussed.

Again, though, I'll defer to someone who's done this stuff more recently than I have (and in a medical area - I was mostly looking at metal-matrix composites rather than anything organic).

[ciphergoth.livejournal.com]

Do you mind if I ask Sandberg to comment on your remarks?

[djm4]

Not at all. I was aware this post was public, and I did explicitly suggest you seek more expert opinion. Don't expect me to have any good rebuttals; I've reached about the limit of my knowledge on the subject, which is OK for engaging with what's written in that PDF, but probably inadequate for detailed discussion of the techniques.

[djm4]

Did he/she ever reply?

You seem to be still treating the PDF as a serious roadmap. I'd characterise it as a 'map of the swamp, with several of the circling alligators marked with an "X"', which I suppose is a roadmap of sorts, but not one that's going to show you the way home.

I'm not sure if you simply don't find my objections credible (fair enough, given the source; my blog reply is hardly a peer-reviewed paper) or whether you have a rebuttal of them.

[damerell.livejournal.com]

But now you aren't, in my view, restoring me to life. You've managed to simulate me - well, good luck to that chap in the future, I'd probably quite like him, I imagine _he'll_ be jolly glad to be alive (from his POV, "again") on less fragile hardware, but I'm just as dead.

[ciphergoth.livejournal.com]

Have you read Hofstadter and Dennett's "The Mind's I"? It's a collection of essays, short stories, and story extracts exploring issues around philosophy of mind. This is almost exactly the question it opens with - using a teleporter rather than WBE, but to the same end. If you haven't, I really recommend it, I think you might really enjoy it.

[djm4]

Yes, I'm not convinced that there wasn't a 'me' in that sense that died last year when I was under anesthetic. Of course, I have his memories, but then I would.

But then, that's true moment-to-moment. As you know, I tend to the view that 'consciousness' itself is an illusion in the sense that most people (including me) think of it, so I'm not sure that I'm saying anything stronger than that with my anasthetic example.

[ciphergoth.livejournal.com]

I'm guessing you've already read how general anaesthesia played a key role in Greta Christina's deconversion?

[ergotia.livejournal.com]

I dont get that one little bit. Drug can put you out as oif you had been mind wiped = cant be life after death? What? Am I just being dumb here? She *was notdead*, she was under anaesthesia!

[seph-hazard.livejournal.com]

I'm not convinced that there wasn't a 'me' in that sense that died last year when I was under anesthetic. Of course, I have his memories, but then I would.

Oh my god - how genuinely, utterly terrifying. Blimey. *shiver* I don't know that thinking that about myself wouldn't send me utterly, utterly barmy.

[akicif.livejournal.com]

I'm not convinced that there wasn't a 'me' in that sense that died last night when I went to sleep. Of course, I have his memories, but then I would.

[ciphergoth.livejournal.com]

Don't worry - it seems like the distinction means something, but it doesn't really.

[wight1984.livejournal.com]

Puts me in mind of John Hicks' Replica theory of the Resurrection, which explores a similar issue.