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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)

#51

Post by SomeoneFromCA »

sooheon wrote: post #43
criddell wrote: post #41

Earlier quoted context omitted.

Is there anything analogous to software in biology?

Biology is the ultimate legacy software running on one of the oldest platforms ever developed, the organic compounds. It is literally a giant genetic algorithm to write instructions (DNA) for manufacturing molecular machines (proteins) that interact with each other in an extremely complex graph of relations (protein pathways, i.e. control flow).

This a very simplistic view, based on assumption that the world is discrete. The whole idea of software relies on the concept of digital computer, a discrete machine. The world might indeed be analogous and real numbers might actually exist.

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

#52

Post by SomeoneFromCA »

lagadu wrote: post #47
otabdeveloper4 wrote: post #40

Earlier quoted context omitted.

The human brain isn't Turing-complete. Turing completeness implies infinite recursion, which the brain obviously can't do.

Technically Turing completeness requires infinite memory for that (or an infinite tape if we're talking about the original turing machine concept), which no Turing-complete machine has. In other words, the brain is as Turing-complete as any machine that we also consider to be so. We'll always be bounded by limited memory and limited time.

We do not know if human brain is indeed Turing-complete, or even if it is a Turing machine at all. Human Mind certainly is, but if brain is or not we do not know.

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

#53

Post by mannykannot »

otabdeveloper4 wrote: post #40
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…

The human brain isn't Turing-complete. Turing completeness implies infinite recursion, which the brain obviously can't do.

While I agree that comparing a human brain or mind to a Turing machine is not helpful, the objection you make here is less significant than it first appears.

There is a subtle difference between unbounded recursion, which a Turing machine is taken to be capable of, and the actual ability to achieve infinite recursion. In no application of a Turing machine, either as an actual physical device or as a hypothetical one in a logical argument, is it ever required to perform infinite recursion, which would just be one way of not halting.

For all practical and theoretical purposes, what matters is that the machine being considered does not exhaust its ability to recurse while performing the computations being considered. Consequently, the standard practice, of saying that computers and certain other devices are Turing-equivalent, with the usually-implicit caveat of being so up to the limit of their recursive ability, is both reasonable and useful.

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

#54

Post by shawnz »

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…

> The brain cannot simulate a turing machine. It does not have infinite memory, which is a requirement for a turing machine.

In practice we call modern computers turing-complete even though they don't have infinite memory. The brain can simulate such a machine.

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

If this mattered, then it would mean analog computers are more powerful than digital computers and therefore the Church-Turing thesis is wrong

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

#55

Post by sooheon »

SomeoneFromCA wrote: post #51
sooheon wrote: post #43

Earlier quoted context omitted.

Biology is the ultimate legacy software running on one of the oldest platforms ever developed, the organic compounds. It is literally a giant genetic algorithm to write instructions (DNA) for manufacturing molecular machines (proteins) that interact with each other in an extremely complex graph of relations (protein pathways, i.e. control flow).

This a very simplistic view, based on assumption that the world is discrete. The whole idea of software relies on the concept of digital computer, a discrete machine. The world might indeed be analogous and real numbers might actually exist.

I think the assumption that software may only be digital is the limited one.

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

#56

Post by kalcode »

ResidentSleeper wrote: post #44
tegeek wrote: post #15

Earlier quoted context omitted.

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.

Whether or not it's comparable depends on the level of distinction you're trying to make. Obviously, CPUs don't think or experience the world (but on the other hand that kind of "feature" seems increasingly likely to be implementable in software, even if our current CPU architectures are rather unsuitable for that goal). However, if we're gonna talk about energy efficiency and computation performance, now that it has…

> now that it has become evident that the brain is merely a kind of a computer

I am ignorant in this area. But I keep reading how brains are nothing like computers the more we learn. Your statement seems to suggest otherwise and id love to read about it. Can you drop something where I can start exploring about how the brain has become more evident that it's merely a kind of computer? Thanks!

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

#57

Post by the_af »

The_rationalist wrote: post #23
tegeek wrote: post #15

Earlier quoted context omitted.

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.

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 similar to CPUs. It might be interesting to consider the question, of course.

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

#58

Post by deegles »

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…

The big question is whether a CPU can emulate a brain with the same or better efficiency.

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

#59

Post by mannykannot »

The_rationalist wrote: post #23
tegeek wrote: post #15

Earlier quoted context omitted.

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.

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…

I am not convinced of the usefulness of this comparison.

The first of your big missing pieces starts from the best that we have been able to achieve with computers so far, and while its completion might be a big step in computing, it would not necessarily be a big step in understanding the human brain - after all, quite primitive animals have impressive abilities in this regard. Using the best computing has done as the yardstick for quantifying the human brain's ability is the wrong way round.

The remaining missing pieces are vague, with no clear indication that they fit into the brain-as-CPU model. For example, while it is true that "[human languages] are in many ways far superior to current GQL/datalog/SQL DB languages at encoding and retrieving meaning (that is an isomorphic description of a denoted thing)", this vastly understates the capabilities of language. Once again, you are using current technology as the yardstick, with no basis for assuming that it is of the right scale.

Overall, you seem to be assuming that the rest of the puzzle is almost within reach. That is certainly a logical possibility, but not one with a great deal of objective evidence in support. FWIW, my opinion on the matter is that we probably don't even know, in any well-defined way, all the questions to be answered.

Even if we grant the premise that a suitably-programmed computer (not just a CPU) could have capabilities that are a superset of those of a human brain, that would not necessarily justify saying one is very like the other - that would be like saying a dynamo is a solar cell because they both produce electric current.

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

#60

Post by whatshisface »

kalcode wrote: post #56
ResidentSleeper wrote: post #44

Earlier quoted context omitted.

Whether or not it's comparable depends on the level of distinction you're trying to make. Obviously, CPUs don't think or experience the world (but on the other hand that kind of "feature" seems increasingly likely to be implementable in software, even if our current CPU architectures are rather unsuitable for that goal). However, if we're gonna talk about energy efficiency and computation performance, now that it has…

> now that it has become evident that the brain is merely a kind of a computer I am ignorant in this area. But I keep reading how brains are nothing like computers the more we learn. Your statement seems to suggest otherwise and id love to read about it. Can you drop something where I can start exploring about how the brain has become more evident that it's merely a kind of computer? Thanks!

The brain is thought to be merely a computer in the original sense of a long strip of paper along with a scribe and a rulebook. The logic is, a Turing machine can simulate quantum electrodynamics to an arbitrary degree of accuracy. Then, two beliefs about physics and the structure of the brain are included:

1. There is nothing going on in the brain that would require simulation to infinite accuracy. Not even a chaotic system would have this property, because they take a finite time to "blow up" an initial uncertainty, and the smaller the initial uncertainty the longer they take to blow up. For this proposition to be violated there would have to be an undiscovered fininite-time nondeterministic blowup, which is unlikely, but I've heard rumblings that we haven't proven that it can't happen in Navier-Stokes. So maybe it can happen in the brain.

2. There is nothing going on in the brain that depends on nuclear physics or anything more "powerful" than quantum electrodynamics.

I have not seen any evidence that 1 or 2 aren't true for the brain, so that puts something behind saying it's "merely a computer."

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