I was wondering why this seemed so outdated and ignorant for something published in 2018 (only 10b transistors? 'computers are serial', really?), but I see that it's from a 2015 textbook, using citations for computing hardware published in 2008, and presumably referencing hardware from 2007 or earlier...
Why Is the Human Brain So Efficient? (2018)
101–110 of 173 posts
Re: Why Is the Human Brain So Efficient? (2018)
#102Earlier 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…
The argument isn't "something like, or a little better, than current CPUs can perform everything a brain can," but something more like "a turing machine can perform everything a brain can or more." This is more an ontological exercise, not an empirical one. If you reduce everything to a "black box" model with inputs and outputs, then sure, the mathematical abstractions of theoretical brains and theoretical CPUs have…
Being skeptical of the claim that a certain qualia is not modelable in machine is just as valid as being skeptical of the exact opposite. This is exactly why I asked if there was anything beyond what the original poster said. Without it, a post based on the exact opposite assumption could have been written and considered just as valid.
Re: Why Is the Human Brain So Efficient? (2018)
#103Earlier quoted context omitted.
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?
Fruit flies can drink wine.
Doing maths - well, it is a common trope that we extrapolate skills of a fraction of humans on the entire population. For an average human 1/3 + 1/2 can be problematic.
Abstract counting up 5 or so - well, many birds can do that, including pigeons.
Re: Why Is the Human Brain So Efficient? (2018)
#104Earlier quoted context omitted.
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.
If world did run on real numbers that we could harness for computation I would be more than happy, because using those we would be able to perform hypercomputation. See https://en.m.wikipedia.org/wiki/Real_computation However this is forbidden by Bekensteins bound, so unless modern physics is horribly broken it’s ruled out at least in any sense visible to us even in principle.
Not a quantum physicists, but IMO Bekenstein bound is not applicable here, because quantum laws are non-deterministic, therefore you can describe the structure of a system, but you cannot describe how it will evolve. Quantum randomness might be in the very essence of how the brain and mind works.
Re: Why Is the Human Brain So Efficient? (2018)
#105I imagine a group of dogs sitting around and asking "How are we so good at thinking about fun ways to play with squeeky toys?". The truth is, that our ability to reason about ourselves is limited by our ability to reason. Perhaps there are aliens out there who would laugh our cognitive abilities--their's being so much better than ours.
Less complicated systems successfully reason about more complicated systems all the time. Ditto for self-reasoning. See: bootloaders, update systems, and package managers.
In order to prove that some kind of meta-cognition is inherently beyond our grasp, you don't just have to prove that the system we are attempting to reason about is more complex than ourselves, you also have to prove that the problem isn't meaningfully reducible. Otherwise we can and will eventually figure out the mental tools we need to tackle the problem, and tackle it.
The same applies to brute physical strength. Humans have no problem building machines vastly stronger, tougher, larger, more precise etc than ourselves even though narrow-minded reasoning might lead you to believe that this was impossible ("a tool can only cut something less hard/strong than itself," "a ruler can only measure less precisely than itself" etc).
Re: Why Is the Human Brain So Efficient? (2018)
#106Earlier quoted context omitted.
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…
To be fair, CPUs are Turing machines. That makes them much more comparable to anything that mainly does information processing than to anything else.
I think the danger is that it's always "obvious" that the current fashionable tech works in analogous ways to the mind/brain. We can spend all day finding ways in which they are similar; for example how the brain does information processing and the CPU does too.
The point is, I think, people from the steam engine era had similar reasons why the mind/soul was exactly like a steam engine. I won't try to reproduce them here, but I'm sure there were convincing arguments at the time. Who has the awareness to claim, before the current fashionable technology becomes unfashionable, that maybe no, the brain is not a close match for an information processing machine? ;)
Re: Why Is the Human Brain So Efficient? (2018)
#107They 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…
Exactly. We shouldn't be so arrogant in thinking the modern computer is the same thing as a human brain.
This comparison is pointless. The human brain is beyond comprehension. Computers are just logic calculators.
Re: Why Is the Human Brain So Efficient? (2018)
#108Earlier 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…
But steam engines and hydraulics and gear mechanisms are all Turing complete. There is nothing wrong with those models. You could build a brain out of any of them, unless the brain computes something that is not computable.
If the brain does something that is not computable, that's a direct challenge to some of our most established science. It is possible, but I think very unlikely.
Re: Why Is the Human Brain So Efficient? (2018)
#109Earlier quoted context omitted.
"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 mo…
Isn't the recent Google quantum "supremacy" experiment evidence against the extended Church-Turing thesis?
Re: Why Is the Human Brain So Efficient? (2018)
#110Earlier 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 has no such constraint. It is analog, and therefore infinite in State representation.
This is a common misconception.
I'm sure you are aware that analog signals can be approximated by digital values -- a 10 bit ADC will read a channel to one part in 1024, etc.
You might say that even a 64 bit representation is a poor approximation of a real life signal, which is a real number with infinite precision... But it isn't.
The brain operates at about 300 Kelvin, and so there's a noise floor to all analog signals of about that times Boltzmann's constant, or 10^-20 J. If a neuron impedance is 1 ohm, and at a bandwidth of just 10 kHz, the thermal noise is about 1 nV. For a membrane potential of 100 mV, that's a maximum possible noise to signal ratio of one part in 100 million, which is 26 bits.
Now the brain could depend on the signal below the noise floor, but if so those would be extremely fragile operations, and you could get the same thing on a computer by padding your numbers with random data.