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Why Is the Human Brain So Efficient? (2018)

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Re: Why Is the Human Brain So Efficient? (2018)

#81

Post by canjobear »

kristopolous wrote: post #69

They aren't the same thing. They are different classes of objects, different tasks. This comparison is kind of silly. I'd hate my computer to have the memory accuracy or the computational accuracy of my brain. I'd hate to have the creativity and inspiration of a computer. Delete being such a nontrivial operation is probably a good thing for humans. Copy being imperfect probably has something to do with the phenomenon…

When we say the brain has poor computational accuracy, we’re usually talking about the conscious brain we’re aware of. But our low-level motor actions and perceptions, coordinated by the brain, require a lot of precise computation. These low-level brain computations are the thing to compare to AI, not our conscious thinking. Our conscious mind is more like low-precision software running on top of an enormously powerful computer.

Re: Why Is the Human Brain So Efficient? (2018)

#82

Post by derefr »

tegeek wrote: post #15
est31 wrote: post #9

One kind of efficiency which hasn't been talked about is the energy loss of things like state switching and keeping the current state enabled. I think that brains build on much more efficient primitives than the silicon transistors computer chips use and thus can perform far more computations for far less energy than a desktop CPU. Another difference between CPUs and brains is that brains are much less general purpos…

Comparing Human Brain with a CPU is misconception. In the past when we didn't have digital computers we used to compare Brain with other machines. And now with a CPU. A Brain from a primitive neuron to higher level is not comparable to any machine at all including the CPU.

The difference is that CPUs, unlike those other machines, can be used to model/simulate things that are similar to brains. There is impedance in the translation, of course, but that impedance can be measured as a sort of “distance” between the architectures; just like one might measure the “distance” between two Instruction Set Architectures.

Re: Why Is the Human Brain So Efficient? (2018)

#83

Post by [deleted] »

coreyp_1 wrote: post #77
supergarfield wrote: post #67

Earlier quoted context omitted.

As far as I understand, the prevailing opinion is that the brain is a physical object and that its operation does not involve currently-unknown laws of physics (because we have a good understanding of what happens at the scale of an entire atom or above). A Turing machine can run a simulation based on such physical laws to any desired level of precision (which is enough, because as mentioned in TFA, processes in the…

"any desired level of precision" is actually the issue. The moment you choose a level of precision, you cease being accurate (at that level). If you make the argument that a TM has infinite memory, and can therefore represent an infinite precision, then I would counter that our current defintion of a TM requires a finite tape alphabet (and finite number of states), which is part of the TM's known computational limita…

[deleted]

Re: Why Is the Human Brain So Efficient? (2018)

#84

Post by TomMarius »

the_af wrote: post #57
The_rationalist wrote: post #23

Earlier quoted context omitted.

Comparing Human Brain with a CPU is misconception. no it is not. Yeah architecturally they are very different and CPU are arguably more programmable / general and less efficient. What does matter is whether CPUs are theoretically able to achieve all the things that a brain can do (and even more) And indeed CPUs as turing complete, programmable machine are a strict superset of what brains can do. The gap between what…

Before CPUs existed, we would compare brains to steam engines. There was a very interesting article posted here on HN a while ago, explaining why humans always pattern match their understanding of the "mind" (or "soul") to whatever technology is fashionable in their time: steam engines, computers, etc. It also explained the pitfalls of doing so. I think there is at this time no indication human brains are in any way…

I thought it was about similarity of simulated neurons, not the CPU itself.

Re: Why Is the Human Brain So Efficient? (2018)

#85

Post by nicoburns »

coreyp_1 wrote: post #49
The_rationalist wrote: post #23

Earlier quoted context omitted.

Comparing Human Brain with a CPU is misconception. no it is not. Yeah architecturally they are very different and CPU are arguably more programmable / general and less efficient. What does matter is whether CPUs are theoretically able to achieve all the things that a brain can do (and even more) And indeed CPUs as turing complete, programmable machine are a strict superset of what brains can do. The gap between what…

"And indeed CPUs as turing complete, programmable machine are a strict superset of what brains can do." This is a fundamental assertion that I do not believe you can make. The brain cannot simulate a turing machine. It does not have infinite memory, which is a requirement for a turing machine. It can, however, stimulate a linearly bounded automata. It is also not implicitly obvious that a turing machine can simulate…

I mostly agree with your post but:

> The brain has no such constraint. It is analog, and therefore infinite in State

Not necessarily infinite. A lot of people believe that nothing in the world is truly infinite (just very large/small). Infinite quantities in mathematics are just approximations that simplify calculations.

Re: Why Is the Human Brain So Efficient? (2018)

#86

Post by rantwasp »

jcims wrote: post #71
stared wrote: post #39

I wouldn't say that human brain is that efficient (per volume). Compare and contrast with the brain of rats or Corvidae: https://www.youtube.com/watch?v=ZerUbHmuY04 .

It's not even a good example. Humans are about the least physically agile vertebrates on the planet. Think of a fruit fly. It can walk, fly, forage for food, mate, etc. The entire critter has a mass of .2mg and their brains have ~135k neurons. Making the horrible assumption of linear power scaling, that's one microwatt.

but can it do math? can it paint? drink wine and muse on its own brain efficiency?

Re: Why Is the Human Brain So Efficient? (2018)

#87

Post by simiones »

marcosdumay wrote: post #73
cmehdy wrote: post #66

Earlier quoted context omitted.

> CPUs as turing complete, programmable machine are a strict superset of what brains can do In what way can this be proven? It's very tempting in an era of tech-centered growth to think of computers as the solution to everything, but we are barely even beginning to understand the brain. We know computers fairly well and can talk about them, but how can we make such a claim when we don't know the other thing we're tal…

> In what way can this be proven? Proven? Nothing in science is ever proven. But on half a millenium we have failed to find anything that can't be simulated by math, and Turing completeness means a computer can simulate anything that can be simulated by math. We also can simulate all the smallest components of a brain. At this point the claim that math can not simulate it is highly extraordinary.

> Turing completeness means a computer can simulate anything that can be simulated by math

Technically, it is not proven that Turing machines can compute all computable functions, so there is some purely theoretical possibility that the brain could be able to compute functions that a Turing machine can't.

Personally I find that extremely unlikely, and agree that it would be extremely surprising. But it wouldn't invalidate anything we have proven so far.

Re: Why Is the Human Brain So Efficient? (2018)

#88

Post by mamon »

coreyp_1 wrote: post #77
supergarfield wrote: post #67

Earlier quoted context omitted.

As far as I understand, the prevailing opinion is that the brain is a physical object and that its operation does not involve currently-unknown laws of physics (because we have a good understanding of what happens at the scale of an entire atom or above). A Turing machine can run a simulation based on such physical laws to any desired level of precision (which is enough, because as mentioned in TFA, processes in the…

"any desired level of precision" is actually the issue. The moment you choose a level of precision, you cease being accurate (at that level). If you make the argument that a TM has infinite memory, and can therefore represent an infinite precision, then I would counter that our current defintion of a TM requires a finite tape alphabet (and finite number of states), which is part of the TM's known computational limita…

> It is possible that the brain's imprecision (I would argue that "inconsistency" might be a better word) is a requirement of it's computational ability

Is it possible that brain is in fact a quantum computer? I can imagine that under all those neural networks there is a small part where, trapped in some complex protein structure, some qbits exist and are crucial to most advanced brain functions, such as consciousness.

Re: Why Is the Human Brain So Efficient? (2018)

#89

Post by satvikpendem »

derefr wrote: post #80
kristopolous wrote: post #69

They aren't the same thing. They are different classes of objects, different tasks. This comparison is kind of silly. I'd hate my computer to have the memory accuracy or the computational accuracy of my brain. I'd hate to have the creativity and inspiration of a computer. Delete being such a nontrivial operation is probably a good thing for humans. Copy being imperfect probably has something to do with the phenomenon…

> memory accuracy There are individuals with very good memories for all sorts of things, who seem to manage to reconsolidate their memories near-losslessly (at least within the confines of the mental schema they organize said memories into.) Surgeons with anatomy, lawyers and judges with case-law, etc. At this point I’m convinced that the lossy method humans intuitively reconsolidate memories with, isn’t so much a fe…

You can even construct memory palaces which are very easy to learn. I still remember them from 10 years ago.

Re: Why Is the Human Brain So Efficient? (2018)

#90

Post by simiones »

supergarfield wrote: post #67
coreyp_1 wrote: post #63

Earlier quoted context omitted.

Regarding the Church-Turing thesis, it is exactly that, just a thesis. Again, akin to P vs NP. It seems to hold for most cases, but is not proven. The reason that it's difficult to apply in regards to the brain is that we don't exactly know how the brain is computing... or if it "computes" at all! To my knowledge, we don't have a model of computation for consciousness, emotion, free will, Etc. Perhaps these are bette…

As far as I understand, the prevailing opinion is that the brain is a physical object and that its operation does not involve currently-unknown laws of physics (because we have a good understanding of what happens at the scale of an entire atom or above). A Turing machine can run a simulation based on such physical laws to any desired level of precision (which is enough, because as mentioned in TFA, processes in the…

> that its operation does not involve currently-unknown laws of physics (because we have a good understanding of what happens at the scale of an entire atom or above)

Well, we know certain approximations of those laws. Purely theoretically, it is possible that the exact laws at some level of detail that we have not yet been able to observe involve functions that are not computable by a Turing machine, and then it is theoretically possible that the brain itself is computing functions which are not computable by a Turing machine (this would of course assume that the Church-Turing thesis is actually wrong).

As long as the Church-Turing thesis is not proven, we can't say with absolute certainty that the physical world can be simulated to any level of detail by a Turing machine.

Furthermore, even if the Church-Turing thesis was proven, is it possible that the physical world involves transformations that are not even computable at all (even if they can be approximated by computable functions)?

Just to be clear, I do not believe these things. But it is fun to think about the limits of our knowledge.

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