PZ Myers on the Infeasibility of Whole Brain Emulation

In the sense I'm thinking of, simulation means modeling the components of a system at a relatively low level — such as all the transistors and connections in a CPU — whereas emulation means replicating the functional behavior of a system.

There seems to be conflicting usage about this.

http://www.fhi.ox.ac.uk/__data/assets/pdf_file/0019/3853/brain-emulation-roadmap-report.pdf

The term emulation originates in computer science, where it denotes mimicking the function of a program or computer hardware by having its low‐level functions simulated by another program. While a simulation mimics the outward results, an emulation mimics the internal causal dynamics (at some suitable level of description). The emulation is regarded as successful if the emulated system produces the same outward behaviour and results as the original (possibly with a speed difference). This is somewhat softer than a strict mathematical definition1. [...]

By analogy with a software emulator, we can say that a brain emulator is software (and possibly dedicated non‐brain hardware) that models the states and functional dynamics of a brain at a relatively fine‐grained level of detail.

In particular, a mind emulation is a brain emulator that is detailed and correct enough to produce the phenomenological effects of a mind.

https://secure.wikimedia.org/wikipedia/en/wiki/Emulation

The word emulation refers to: [...]

The low-level simulation of equipment or phenomena by artificial means, such as by software modeling. Note that simulation may also allow an abstract high-level model.

On the other hand, the top-voted answer at http://stackoverflow.com/questions/1584617/simulator-or-emulator-what-is-the-difference says that

Emulation is the process of mimicking the outwardly observable behavior to match an existing target. The internal state of the emulation mechanism does not have to accurately reflect the internal state of the target which it is emulating.

Simulation, on the other hand, involves modeling the underlying state of the target. The end result of a good simulation is that the simulation model will emulate the target which it is simulating.

Well, when I argued on here last week ( http://lesswrong.com/lw/d80/malthusian_copying_mass_death_of_unhappy/6y2r?context=1#6y2r ) that emulation would be more difficult than people imagine, based on my experience of working on software that does that, people downvoted it and argued "no, people aren't talking about emulation, but about modelling at the molecular level"

Looks like flash memory stores information using varying levels of charge; that would be quite painful to read out with a destructive scan. Happily that's unlikely to be the case with the brain's long-term storage, since AIUI it doesn't contain any sufficiently good insulators.

Now, how would you approach that one?

Step 1 is to construct a superintelligent machine...

Freeze the volatile memory - - this preserves its state (you can retrieve passwords from shutdown laptops this way. an upside down can of computer cleaner will work). Slice it up, scan it (this assumes it wasn't significantly damaged while slicing; some damage is acceptable because what was there can be inferred -- this is a method in data recovery. also, you wouldn't slice it up tbh. probably the same with a brain.). With the scan you should be able to build a 3d representation of the memory with pixels (more information than just rgba). Now, you use some kind of pattern recognition to map patterns of pixels to physical representations (eg. take a Quake map and look for pixel patterns that match a jump pad).

Now, if you understood how the memory and cellphone software works, you could just get the state into a binary form acceptable for a cell phone emulator. But, because we don't understand how it works, we'll need to simulate reality to a sufficient level. I.e., we need an empty emulated universe with physical laws that correspond to our own, so that we can interpret pixels into their physical correspondents. So, when we pattern match a bunch of pixels into a memory cell with a certain state, we can then drop that interpretation into the emulated world.

For the emulated world to be sufficient for emulating the cell phone, I don't think you would need atoms or electrons (or anything below that level). You could probably emulate the components at the level of electricity, silicon, wire, gold, ect, because we can explain and predict the phenomena a phone produces at that level without going further. E.g., we just need to know what an electric current does, not what its electrons are doing to turn on an emulated light bulb.

(This was my internal monologue as I went through this problem. It's not researched, and is intended to be taken more as bar talk than anything very serious.)

That seems feasible if you knew both the model and the operating system, and had a scan showing very precise relative temperatures. You could then match the state of the simulated phone to a long but finite list of the possible states of the phone given the operating system. But I'm not a doctor.

Interestingly, people already try to do this kind of thing http://artematrix.org/archive/computer/restoration.simulation.htm, http://simh.trailing-edge.com/.

Right on.

I'm the blogger PZ was responding to in his post, and I specifically recommended PZ read Sandberg and Bostrom's Whole Brain Emulation: A Roadmap.

That's what PZ is claiming to have read when he writes "I read the paper he recommended," but PZ doesn't seem to have read it very carefully, in particular missing out on the sections "simulation scales" (pp. 13-14), "Body Simulation," and "Environment Simulation" (pp. 74-78). I've written a post explaining PZ's apparent confusions in greater detail at my blog.

Seems similar enough to "Every part of your brain assumes that all the other surrounding parts work a certain way. The present brain is the Environment of Evolutionary Adaptedness for every individual piece of the present brain.

Start modifying the pieces in ways that seem like "good ideas"—making the frontal cortex larger, for example—and you start operating outside the ancestral box of parameter ranges. And then everything goes to hell.

So you'll forgive me if I am somewhat annoyed with people who run around saying, "I'd like to be a hundred times as smart!" as if it were as simple as scaling up a hundred times instead of requiring a whole new cognitive architecture."

Eliezer Yudkowsky, Growing Up is Hard

stuff nobody understands very well yet

He works with brain preservation every day. When he says "this is impossible", he's not being uber-sceptic - he's speaking with annoyance at something he'd love to be able to do and that would make his work a lot easier, but that he has excellent reason to consider practically impossible.

I used to read Panda's Thumb regularly, many years ago, and have read occasional pieces by him more recently. PZ Myers might be competent at whatever field he specializes in, but as a general thinker he is best ignored.

The dogs bark. The caravan moves on.

Putting smileys after jokes such as "Step 1 is to construct a superintelligent machine..." would be a good start. Seems like people are taking such statements seriously -- not surprising, really.

Oops, didn't see a further comment below: In response to a comment, " I still don’t understand why biologists insist that you have to do a perfect simulation, down to the smallest molecule, and then state the obvious fact that it’s not going to happen.", PZ says this:

"Errm, because that’s what the singularitarians we’re critiquing are proposing? This whole slice-and-scan proposal is all about recreating the physical components of the brain in a virtual space, without bothering to understand how those components work. We’re telling you that approach requires an awfully fine-grained simulation.

An alternative would be to, for instance, break down the brain into components, figure out what the inputs and outputs to, say, the nucleus accumbens are, and then model how that tissue processes it all (that approach is being taken with models of portions of the hippocampus). That approach doesn’t require a detailed knowledge of what every molecule in the tissue is doing.

But the method described here is a brute force dismantling and reconstruction of every cell in the brain. That requires details of every molecule."

Still seems like a straw man.

It is unclear why this apposite technical reference got downvotes.

My hypothesis is that there are a finite number of classes of neurons, glial cells, and classes of synaptic junctions, that bound closely into certain behavioral groupings. In which case, you need only prod enough neurons in petri dishes to develop good statistical models of each type of neuron, glia, and synapse you're modelling. I suspect, but can't prove right now, that only the broad probabilistic behavior of each functional element would be meaningful on the scales we care about.

The reason I believe that is exactly what you said -- it's too noisy. Human brains are way too robust to be extremely sensitive to sub-cellular changes. If you want sub-cellular changes to make a difference (say, in the case of drugs) you have to affect billions of neurons.

EDIT: Actually, you can pretty cleanly rebut his argument about how hard it is to preserve the fish's neural tissue in what he considers to be 'sufficient detail.' If brains really were that sensitive to sub-cellular shifts in neuronal state, there's no way it would be possible for someone to recover from being clinically dead for a few seconds, much less the hours or days that have been observed in cold conditions.

Fixed.

I expect physics is in general incompressible

Why would "physics" be incompressible? Most of the universe is empty space, no?

Fixed.

I would point out that neither are most of us.

Downvoted for being a content-free status move (against someone who's disagreeing with local dogma, but not saying things that are that silly).

This is not only unfair, but misses an important point: Myers works with preserving brains every day. He would love it if brains could be preserved. When he explains in detail why they can't, he's not doing with triumphalism at being more sceptical than singularitarians, he's doing it with annoyance that we can't do this thing he'd really, really love to be able to do.

Well, or maybe not.