This is a rather long reply to a post from ciphergoth. The question being, is it plausible that, in future, we will be able to resurrect people from their head, cryonically frozen post-mortem?

I am keenly interested in the prospect of whole-brain emulation, which strikes me as potentially plausible, with reasonable probability. For one thing, I think that this is one of the more doable routes to AI - rather than trying to build a mind from scratch, to instead try to bootstrap it by attempting to reproduce the existing biological structures.

This being the case, it begs an obvious question, as it were: once (implicit "if" here & from now on) we have WBE, then the next big desirable leap would be scanning a biological brain and running the resultant dataset on an emulation. IOW, Kurzeilian "uploading". This strikes me as a consummation devoutly to be wished.

However, I feel - as a long-ago biology grad - that the prospects for taking a complete adult brain, scanning it & getting any data out of it that is worth uploading are virtually 0. I will come back to this in a moment.

But this is starting with a living, functioning brain - albeit possibly impaired by old age, disease or trauma. (Because why would one choose to do it if alive & healthy?)

However, the prospects of doing it from a dead brain seem to me to be far closer to 0, in a Zeno's-Paradox sort of way. Once one is outside that critical 4min window of an oxygen-deprived brain, I suspect that the remaining amount of useful information drops precipitately, with every passing minute, and after 2-3x that 4min window, I suspect there isn't enough left to be worthwhile. Given some hand-waving magical technology for interpreting memories absent the consciousness that recorded them - and of course we don't know if different consciousnesses record them in compatible or even comparable formats - one might be able to retrieve some memories from a dead brain, but a mind? I doubt it.


Now we are, ISTM, approaching really quite closely to 0. But taking the additional step of freezing the dead brain first, with all the damage that the process causes, and I think we can watch the decimal point recede into the distance as we're down into the 99.9 and lots more nines % probability that there is nothing left to recover.

I will skip the process of thawing the brain before recovery. From my reading, AIUI, people in coma, after cardiovascular incidents, chilled after falling in frozen rivers, etc., are often in a dormant but viable state; it is the process of recovery that is fraught. Again AIUI, it is the return of oxygen to the tissues in an uncontrolled fashion that often causes massive damage.

If we are merely trying to recover the mind that (might) be still stored in a frozen brain, then why thaw it? If there is a Plot Device™ magical brain scanning machine, then let us hypothesize one that can work on a frozen brain & avoid all the damage caused by thawing it.

So let us skip that part. We freeze the brain, very fast, somehow without causing microfractures, cellular rupture from ice crystal formation, etc. etc., and we manage to do this within 4min of death. Lot of big “ifs” in there. But if we can do that, then safer to find a way to sample the frozen brain without thawing.

So there are a succession of problems here:

[1] Getting to the person soon enough after death – I think preservation will need to be done within the same time period that revival would be.

[2] Freezing the brain inside that period, without damaging it – major implementation difficulty here.

[3] Implicit in #2, a preservation method that preserves the structures or patterns that encode the mind in question. Currently more or less impossible to say, as we don't know what structures or patterns those are.

[4] Sampling the result with fine enough resolution to retrieve useful amounts of info.

[5] Finding a way to process, implement or run the resultant dataset in a way that will effectively resurrect the consciousness.

That is one hell of a big list of implementation details there. I find them daunting, frankly.

Now, to skip back to the issues-with-scanning-a-living-brain thing I mentioned in ¶5.

I do not find this plausible with any technology that is usefully distinguishable from magic. You need not only an accurate synapse-level model, you also need measurements of the distribution of a whole slew of fairly fragile little molecules – dopamine, acetylcholine, adrenaline & noradrenaline, &c. &c. - not only within the cells but possibly also in the distribution between cells. One may also need information about the movements of these chemicals; this is a dynamic process we're talking about here, involving flows, gradients and so on, in the cytoplasm of the neurons and possibly in the synapses too. We simple do not know yet how most of this works, so we don't know what needs to be sampled or stored. In some cases we don't know the fine detail, in others, not even the outlines. What we do know is that it is a very complex dynamic system.

(This is one of the major reasons I find the prospect of resurrection from dead, frozen brains so implausible as to be massively improbable. I think by the time the meat is frozen, “you” are long gone.)

But let's say we had such a machine. To get this level of detail, you need to go inside the cells; it seems highly probable that the scanning process is therefore destructive. Very destructive.

Now if one had a Plot Device that could take the top off someone's head and start scanning at 1mm/sec, capturing all that ultramicroscopic detail – and given the volumes of data and the size of the structures, that is *fast* - then it's no use, because by the time you are 1-2cm in, the patient is dead, and the rest of the data is therefore useless.

In this thought experiment, in fact, it doesn't really matter how fast your machine is, because if you start at one point and work through – and if our machine goes at 1cm a second, and boy is this going to be one messy machine, a device for rapidly turning heads into a cloud of pinkish mist - then still, after you're a short way in, the rest of the brain collapses into a chaotic mess and there's no data left to sample. The machine will have a broadly similar effect to a dumdum bullet to the frontal lobes.

Essentially this seems to me like an insurmountable problem.

Even an imaginary machine that could destructively sample a whole brain in a fraction of a second – and I think it's a safe bet it would be destructive at such a speed – is going to work at such a speed that the waste heat would cook the brain being sampled and again destroy the data being acquired.

The size of the system and its fragility precludes effectively sampling a living system, and as discussed, I think that only a living brain is worth sampling; a dead one, I suspect, would not contain enough information to get a functioning mind out of it.


This leads, ISTM inevitably, to non-destructive sampling: to trying to design and build a system that can record the state of a whole conscious brain, while it is working, and record the info in such a way as to allow a functioning copy to be built.

Given the previously-discussed fine detail needed, then this is not going to be a magic cap you put on like a hat. The sampling probes are going to need to be right in there, up alongside the dendrites, sampling their activity over a period of time.

This seems to me to mandate nanotechnology, basically. You are going to have to grow the sensor system inside the brain & the end result will be of comparable complexity to the brain itself. It has to be.

(This leads to the mechanistic argument against all-knowing deities: any omniscient deity must be a system of equal or greater complexity to the universe in which it is omniscient, therefore, it must be bigger than the universe. But it has to know itself, too, so it has to be bigger than itself, which is clearly impossibe; therefore, omniscience is impossible. And if it's not omniscient and/or omnipotent, then it's not a deity.)

But one for a single human brain? That is imaginable.

Growing this sensor network will be slow, because if you do it fast, you'll cook the brain. So it probably has to be implanted in the person some time before – possibly years before. Possibly even at birth or soon after. Also, you need damned small sensor nets, as they have to fit into the gaps without disrupting the dendritic structures.

Given that - and at this point I think it's obvious you need nanotechnology to do it – then I find the prospect of getting enough data, and good data, to have a chance of replicating it.

Which just leaves the non-trivial problem of building something that can run it.

But if you have nanotech good enough to build the sensor, the computer to run the dataset is probably not a problem.

If enough data persisted in a dead, frozen brain, of course, one could grow the sensor net slowly in that. They're dead, they won't mind waiting. But I don't think enough data would persist; it is fairly logically clear that minds are dynamic systems & I don't think you can just turn off the hardware, stop it in place, then restart it again later. I would be very happy to be proved wrong on this point, but until neuroscience moves on a fair bit, we won't know.

[Deep breath]

Next comes the mundane issues:
[1] Can you trust the cryonics company to keep your head in good nick?

[2] When the technology exists to resurrect corpsicles, who is going to do this and why? Who pays? Why should they bother? What if they're in an overpopulated future (a very safe bet for the foreseeable one), why would they want more people in the form of resurrected dead? Perhaps they might bother bringing back genius scientists, great artists, and so on, but ordinary Joes? Why?

[3] In what form would you get resurrected, or want to be? As a flesh human in a cloned body? As an awareness in a robot body? As a purely simulated awareness in a virtual space?

[4] Assuming the hypothetical future society does resurrect people if it can, what for? What if you're a cheaper equivalent to an AI, managing stock databases for a subjective millennium? Would you want that?

There are so many ifs and buts in the way, I do not see it as a useful option. Personally I would rather bet on uploading of live people while I still am one.

Which allows me to end on a song, with only a minor rewrite of the lyrics...

I'm your prime cut of meat, I'm your choice
I wanna be uploaded...