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The Brain is Not Computable

technologyreview.com

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Re: The Brain is Not Computable

#11

Post by tibbon »

My girlfriend is a neuroscientist. Every time she sees something about them 'modeling the brain' she is visibly amused/unhappy. It might be possible, but our current understanding of the brain feels much further away.

The concept that we're going to hit some moore's law style thing in science that will propel us to just automatically understand things, which we can barely measure currently, just doesn't line up. Just the process to understand how a single thing functions on a single channel seems to take forever now, and most neuroscience labs aren't limited by the speed of their desktops...

Re: The Brain is Not Computable

#12

Post by kybernetikos »

guylhem wrote: post #3

Not with our current technology, I agree But saying the problem can't be solved ever seems dead wrong to me. We humans excel at understanding and replicating what nature did - then at improving it. Once we clearly understand how memories are stored, if they can be read and written that'll be half of the problem : accessing the data. If the theory about memory being encoded in the microtubules is right, imagine some n…

Computability in this case is a theoretical term and doesn't really relate to levels of technology.

Whether or not all physical processes are computable in the sense that they can be simulated by a turing machine is an open question, although my impression is that most folk who care to express an opinion think that they can. There's a little bit more on the Wikipedia article on the Church-Turing-Deutsch principle. http://en.wikipedia.org/wiki/Church%E2%80%93Turing%E2%80%93D...

Re: The Brain is Not Computable

#13

Post by Xcelerate »

I'm going to take the unpopular stance and say that it's very hard to make a prediction like this. Anyone who has a very strong stance one way or another probably needs to reevaluate their predictive capabilities.

I do work in molecular dynamics. To even simulate a million atoms requires huge approximations. You can get more accurate as you simulate less. If you want an almost perfect match with reality, simulation will get you about 2-3 helium atoms. Now consider how many atoms are in a human brain.

So it's hard for me to imagine fully simulating a human brain, although I don't see why it is theoretically impossible. Brains behave according to the same laws of physics as everything else in the universe.

On our current technological improvement path, I don't see a brain simulation occurring any time soon. If quantum computers were developed, it would make things much easier, but we would still need a new "kind" of technology. I wouldn't rule it out completely though. Who in the 1600s would have predicted microprocessors?

As for his talk about souls or consciousness, that just confuses me (and I'm religious too). Everything that we have thus far discovered obeys the laws of physics, so ruling out a simulation via some mystical "property" that human brains have seems sketchy to me.

Now, if you want to talk about things that really aren't computable, I'll direct you to Chaitin's constant: http://en.wikipedia.org/wiki/Chaitins_constant

Re: The Brain is Not Computable

#14

Post by zepolud »

rm999 wrote: post #6

>But Nicolelis is in a camp that thinks that human consciousness (and if you believe in it, the soul) simply can’t be replicated in silicon. That’s because its most important features are the result of unpredictable, non-linear interactions amongst billions of cells, Nicolelis says. This is a fringe opinion, and I really wish the title reflected that. Ignoring the absurd 'linear' part of the article, I don't believe…

Even a quantum system could be simulated on classical Turing machine so I fail to see how that relates to computability. The whole article boils down to a metaphysical, a-wizard-did-it, type of argument as usual.

Re: The Brain is Not Computable

#17

Post by Aqueous »

mistercow wrote: post #10

>That’s because its most important features are the result of unpredictable, non-linear interactions amongst billions of cells, Nicolelis says. Replace "cells" with "molecules" and "consciousness" with "fluid dynamics", and you can see what a vague, hand-waving argument this is. >“You can’t predict whether the stock market will go up or down because you can’t compute it,” he says. “You could have all the computer chi…

Right. Tell this to the field of meteorology, or any other discipline that uses computers to simulate chaotic systems. We simulate complex, non-linear systems with computers all the time. Just because we don't have the solution for the differential equation that describes these dynamics doesn't mean that we can't simulate them.

Re: The Brain is Not Computable

#18

Post by bascule »

rm999 wrote: post #6

>But Nicolelis is in a camp that thinks that human consciousness (and if you believe in it, the soul) simply can’t be replicated in silicon. That’s because its most important features are the result of unpredictable, non-linear interactions amongst billions of cells, Nicolelis says. This is a fringe opinion, and I really wish the title reflected that. Ignoring the absurd 'linear' part of the article, I don't believe…

According to Max Tegmark's calculations, the importance of quantum mechanical effects on brain processes is negligible:

http://arxiv.org/abs/quant-ph/9907009

This paper posits the brain can be modeled as a classical (e.g. Newtonian, "billiard ball"-style) physical system

Re: The Brain is Not Computable

#19

Post by Justsignedup »

rm999 wrote: post #6

>But Nicolelis is in a camp that thinks that human consciousness (and if you believe in it, the soul) simply can’t be replicated in silicon. That’s because its most important features are the result of unpredictable, non-linear interactions amongst billions of cells, Nicolelis says. This is a fringe opinion, and I really wish the title reflected that. Ignoring the absurd 'linear' part of the article, I don't believe…

Also we're not trying to reproduce someone's brain and predict what that someone will think... Instead we are trying to reproduce human thought and intellect. That's like saying we can't re-create the stock market somewhere (that has the same basic rules/behaviors, but not the exact same data)...
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