Looking for opinions of people like Nick Bostrom or Anders Sandberg on current cryo techniques

ChrisHallquist

In June 2012, Robin Hanson wrote a post promoting plastination as a superior to cryopreservation as an approach to preserving people for later uploading. His post included a paragraph which said:

We don’t actually know that frozen brains preserve enough brain info. Until recently, ice formation in the freezing process ripped out huge brain chunks everywhere and shoved them to distant locations. Recent use of a special anti-freeze has reduced that, but we don’t actually know if the anti-freeze gets to enough places. Or even if enough info is saved where it does go.

This left me with the impression that the chances of the average cryopreserved person today of being later revived aren't great, even when you conditionalize on no existential catastrophe. More recently, I did a systematic read-through of the sequences for the first time (about a month 1/2 ago), and Eliezer's post You Only Live Twice convinced me to finally sign up for cryonics for three reasons:

It's cheaper than I realized
Eliezer recommended Rudi Hoffman to help with the paperwork
Eliezer's hard drive analogy convinced me the chances of revival (at least conditionalizing on no existential catastrophe) are good

But then Paul Crowley pointed out to me that what I posted yesterday about trusting experts seems to imply I should take cryonics less seriously than I do. I thought about it awhile, and realizes that I suspect that even among academics who would be predisposed to take cryonics seriously, say attendees at the workshop that produced the Whole Brain Emulation roadmap, Robin's more cautious perspective is probably more typical. Or is it? I've tried to find information online, and the one thing I've found is the Scientists' Open Letter on Cryonics, which carries this disclaimer:

Note: Signing of this letter does not imply endorsement of any particular cryonics organization or its practices. Opinions on how much cerebral ischemic injury (delay after clinical death) and preservation injury may be reversible in the future vary widely among signatories.

I don't find that terribly encouraging. So now I'm back to being pessimistic about current cryopreservation techniques (though I'm still signing up for cryonics because the cost is low enough even given my current estimate of my chances). But I'd very much be curious to know if anyone knows what, say, Nick Bostrom or Anders Sandberg think about the issue. Anyone?

Edit: I'm aware of estimates given by LessWrong folks in the census of the chances of revival, but I don't know how much of that is people taking things like existential risk into account. There are lots of different ways you could arrive at a ~10% chance of revival overall:

(50% chance of no existential catastrophe) * (30% chance current cryopreservation techniques are adequate) * (70% chance my fellow humans will come through for me beyond avoiding existential catastrophe) = 10.5%

is one way. But:

(15% chance no existential catastrophe) * (99% chance current cryopreservation techniques are adequate) * (70% chance my fellow humans will come through for me beyond avoiding existential catastrophe) = ~10.4%

is a very similar conclusion from very different premises. Gwern has more on this sort of reasoning in Plastination versus cryonics, but I don't know who most of the people he links to are so I'm not sure whether to trust them. He does link to a breakdown of probabilities by Robin, but I don't fully understand the way Robin is breaking the issue down.

In June 2012, Robin Hanson wrote a post promoting plastination as a superior to cryopreservation as an approach to preserving people for later uploading. His post included a paragraph which said:

We don’t actually know that frozen brains preserve enough brain info. Until recently, ice formation in the freezing process ripped out huge brain chunks everywhere and shoved them to distant locations. Recent use of a special anti-freeze has reduced that, but we don’t actually know if the anti-freeze gets to enough places. Or even if enough info is saved where it does go.

It's cheaper than I realized
Eliezer recommended Rudi Hoffman to help with the paperwork
Eliezer's hard drive analogy convinced me the chances of revival (at least conditionalizing on no existential catastrophe) are good

Note: Signing of this letter does not imply endorsement of any particular cryonics organization or its practices. Opinions on how much cerebral ischemic injury (delay after clinical death) and preservation injury may be reversible in the future vary widely among signatories.

(50% chance of no existential catastrophe) * (30% chance current cryopreservation techniques are adequate) * (70% chance my fellow humans will come through for me beyond avoiding existential catastrophe) = 10.5%

is one way. But:

(15% chance no existential catastrophe) * (99% chance current cryopreservation techniques are adequate) * (70% chance my fellow humans will come through for me beyond avoiding existential catastrophe) = ~10.4%

I reject the computational paradigm of mind in its most ambitious form, the one which says that mind is nothing but computation - a notion which, outside of rigorous computer science, isn't even well-defined in these discussions.

One issue that people blithely pass by when they just assume computationalism, is meaning - "representational content". Thoughts, mental states, are about things. If you "believe in physics", and are coming from a naturalistic perspective, then meaning, intentionality, is one of the great conundrums, up there with sensory qualia. Computationalism offers no explanation of what it means for a bunch of atoms to be about something, but it does make it easy to sail past the issue without even noticing, because there is a purely syntactic notion of computation denuded of semantics, and then there is a semantic notion of computation in which computational states are treated as having meanings embedded into their definition. So all you have to do is to say that the brain "computes", and then equivocate between syntactic computation and semantic computation, between the brain as physical state machine and the mind as semantic state machine.

The technological object "computer" is a semantic state machine, but only in the same way that a book has meaning - because of human custom and human design. Objectively, it is just a syntactic state machine, and in principle its computations could be "about" anything that's isomorphic to them. But actual states of mind have an objective intrinsic semantics.

Ultimately, I believe that meaning is grounded in consciousness, that there are "semantic qualia" too; that the usual ontologies of physics must be wrong, because they contain no such things - though perhaps the mathematics of some theory of physics not too distant from what we already have, can be reinterpreted in terms of a new ontology that has room for the brain having such properties.

But until such time as all of that is worked out, computationalism will persist as a pretender to the title of the true philosophy of mind, incidentally empowering numerous mistaken notions about the future interplay of mind and technology. In terms of this placeholder theory of conscious quantum vortices, there's no problem with the idea of neural prostheses that work with your vortex, or of conscious vortices in something other than a biological brain; but if a simulation of a vortex isn't itself a vortex, then it won't be conscious.

According to theories of this nature, in which the ultimate substrate of consciousness is substance rather than computation, the very idea of a "conscious program" is a conceptual error. Programs are not the sorts of things that are conscious; they are a type of virtual state machine that runs on a Turing-universal physical state machine. Specifically, a computer program is a virtual machine designed to preserve the correctness of a particular semantic interpretation of its states. That's the best ontological characterization of what a computer program is, that I can presently offer. (I'm assuming a notion of computation that is not purely syntactic - that the computations performed by the program are supposed to be about something.)

Incidentally, I coughed up this vortex notion, not because it solves the ontological problem of intentional states, but just because knotted vortex lines are a real thing from physics that have what I deem to be properties necessary in a physical theory of consciousness. They have complex internal states (their topology) and they have an objective physical boundary. The states usually considered in computational neuroscience have a sorites problem; from a microphysical perspective, that considers what everything is really made of, they are defined extremely vaguely, akin to thermodynamic states. This is OK if we're talking about unconscious computations, because they only have to exist in a functional sense; if the required computational mappings are performed most of the time under reasonable circumstances, then we don't have to worry about the inherent impreciseness of the microphysical definition of those states.

But conscious states have to be an objective and exact part of any ultimate ontology. Consciousness is not a fuzzy idea which humans made up and which may or may not be part of reality. In a sense, it is your local part of reality, the part of reality that you know is there. It therefore cannot be regarded as a thing which exists approximately or vaguely or by convention, all of which can be said of thermodynamic properties and of computational states that don't have a microphysically exact definition. The quantum vortex in your cortex is, by hypothesis, something whose states have a microphysically exact definition, and so by my physical criterion, it at least has a chance of being the right theory.

meaning - "representational content". Thoughts, mental states, are about things. If you "believe in physics", and are coming from a naturalistic perspective, then meaning, intentionality, is one of the great conundrums, up there with sensory qualia. Computationalism offers no explanation of what it means for a bunch of atoms to be about something

What do you think of Eliezer's approach to the "meaning" problem in The Simple Truth? I find the claim that the pebble system is about the sheep to be intuitively satisfying.

3Ishaan13y

Is that a prediction then? That your family and friends could somehow recognize the difference between you and a simulated copy of you? That the simulated copy of you would somehow not perceive itself as you? That the process just can't work and can't create anything recognizably conscious, intelligent, or human? (and does that mean strong AI needs to run on something other than a computer?) Or are you thinking it will be a philosophical zombie, and everyone will be fooled into thinking its you? What do you think will actually happen, if/when we try to simulate stuff? Let's just say that we can do it roughly down to the molecular level. [...] What precludes us from simulating something down to the sufficiently, micro physically exact level? (I understand that you've got a physical theory of consciousness, but i'm trying to figure out how this micro-physical stuff plays into it)