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The Brain is Not Computable

technologyreview.com

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Re: The Brain is Not Computable

#31

Post by api »

I'm somewhere in between. I think it might be possible to create a machine that does what the brain does, or even to "upload," though I don't see the latter anytime in the foreseeable future.

But if so, I don't think it'll be with a standard von Neumann machine. Not that such a computer couldn't perform the required computations... it's Turing complete. But I think it would be a very poor fit for the problem domain. You'd want some kind of radically different incredibly highly parallel architecture. You also might want it to be analog or analog-like. There's been some interesting renewed interest in analog computers for a little while, and in probabilistic processors that can run incredibly fast by discarding the requirement of perfection.

Re: The Brain is Not Computable

#33

Post by Aqueous »

defen wrote: post #23
Aqueous wrote: post #17

Earlier quoted context omitted.

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.

The problem with chaotic systems isn't simulating them, it's measuring the initial conditions. Arbitrarily small differences blow up exponentially fast even if your simulation has really, really small time steps.

The differences in initial conditions do cause the trajectories to diverge, but in certain systems they don't just diverge, they also get pulled into the orbit of an attractor, such as the Lorenz attractor. So, the behavior overall, despite being seemingly chaotic, is actually predictable and ordered.

Re: The Brain is Not Computable

#34

Post by amalag »

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…

How are you conflating randomness with unpredictability?

Re: The Brain is Not Computable

#35

Post by [deleted] »

muglug wrote: post #22
Xcelerate wrote: post #13

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 w…

As I understand it, currents attempts to simulate brain activity operate on a slightly higher scale, mimicking the behaviour of neurons and the electronic signals between them, without resorting to modelling the behaviour of individual atoms.

[deleted]

Re: The Brain is Not Computable

#36

Post by Vivtek »

Oh come on. I'm not going to make a prediction one way or the other, but there's one thing I do know: simulating the brain and simulating the current stock market to predict the outcome of a stochastic process (which is unknowable because you don't even know the inputs) are two vastly different things. So that's a really weak argument for his position. Not an argument for it at all, actually.

Re: The Brain is Not Computable

#37

Post by VMG »

mehwoot wrote: post #24

I too believe this. Here is my argument: 1) If we have to simulate it at a low level, the human brain is far too complex for any computer in any timeframe of our current lives to have enough power to simulate properly 2) Working backwards and simulating the high level processes (AI, etc) have been a dismal failure at actually replicating human thought processes, and will continue to be. While NN or the like can theor…

> I too believe this.

You don't. The article argues that there is a theoretical barrier that prevents a brain emulation in principle, you argue that technology isn't ready yet and won't be in our lifetimes.

Opponents of your viewpoint argue that you simply can't imagine the state of technology in 50 years.

Re: The Brain is Not Computable

#38

Post by MaysonL »

Xcelerate wrote: post #13

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 w…

Boyle's Law is statistical, but pretty damn accurate, even though it's nowhere near a simulation of the dynamics of the myriad molecules whose dynamics it aggregates.

Re: The Brain is Not Computable

#39

Post by tibbon »

Aqueous wrote: post #21
tibbon wrote: post #11

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…

Right, it takes forever now - and it took twice as long five years ago.

But the thing is most neuroscientists don't just sit at a computer all day. 95% of the tasks they do are not computer-bound.

If you're doing animal-based research (the majority of real neuroscience currently), then its time spent with behavior testing, surgeries, waiting for the drug to be in an animal for 72 (or however many) hours, processing slides, pipetting, etc.

The time spent at a computer is mostly data analysis, reading papers, ordering supplies and grantwriting. A huge amount of time seems to be spent jumping through hoops, ordering things, working with vendors of equipment that doesn't frequently work as advertised, and dealing with broken stuff overall. The data-analysis they are doing again, isn't bound by the computer's speed. It generally is working with a few dozen (or hundred) samples of relatively computationally easy data.

There's not much for a computer to speed up.

Re: The Brain is Not Computable

#40

Post by kristofferR »

I simply can't understand why people feel the need to proclaim that something plausible will never ever happen some time in the (possibly very distant) future. It's both stupid, unproductive and often embarrassing (when they are proven wrong).

>"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.

I'm guessing/hoping that the silicon reference was made by the author of the article and not Miguel Nicolelis, considering that silicon is extremely likely to be replaced by graphite or something else in the next decade or two, at least with almost full certainty by the next century. If it actually was Nicolelis who spoke about silicon, it automatically discredits him from having anything to say about the distant future of computing.

>That’s because its most important features are the result of unpredictable, non-linear interactions amongst billions of cells, Nicolelis says."

Even if that was true, which I doubt, so what? There has to be some kind of a system behind those "unpredictable, non-linear interactions" in order for the brain to have any functionality at all, and every system can be figured out and simulated. It might be incredibly complex and take centuries for us to gain the required knowledge and processing power, but even that doesn't make it impossible.

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