4 ms·

What are these limits and how do you know they exist?

gtirloni 13y ago
Can we create digital logic circuitry that embodies ALL the functionality of a neuron, including interconnections (and here you have to compensate circuitry limitations that the neurons don't have) in the same size? I think you can start from there to understand current technology's limitations. I agree we will likely not be calling these things "computers", if we ever invent them.
- skywhopper 13y ago
  Even if you remove the size restriction and the physical limitations of manufactured circuitry, we're lacking the perfectly defined model of how a neuron actually works. We have plenty of knowledge about neurons, but nowhere near enough to simulate them realistically. You'd need to be able to account for every possible state a neuron could ever be in. But a neuron is more than just an input-output state machine, it's affected by levels of oxygen, glucose, and any number of hormones, proteins, and other chemicals in the bloodstream. An adult human's neurons are each individually shaped by their entire existence up to that point. Alcohol consumption, sun exposure, antidepressant medication, hydration levels, exercise levels. It all affects how they work. And that's just one neuron. Simulating the brain as a solution to this problem is, I think, out of the question.
  - platz 13y ago
    Defining a computer in terms of transistors and logic gates is analagous to defining a brain in terms of neurons and synapses. You arbitrarily impose limits in the definition of a computer and lift those limits in definition of a brain.
  - Houshalter 13y ago
    >An adult human's neurons are each individually shaped by their entire existence up to that point. Alcohol consumption, sun exposure, antidepressant medication, hydration levels, exercise levels. It all affects how they work. Possibly, but why on Earth would you want to simulate that? Just simulate what the neuron is supposed to be doing or would be doing under ideal circumstances.
    - gnaritas 13y ago
      > Just simulate what the neuron is supposed to be doing or would be doing under ideal circumstances. We still don't know that either.
  - nswanberg 13y ago
    It wasn't necessary to simulate a feather in bird's wing in order to fly. In fact, practical flight really only happened once people started taking away features observed in nature.
skywhopper 13y ago
There's a whole subfield of computer science about it: http://en.wikipedia.org/wiki/Theory_of_computation http://en.wikipedia.org/wiki/Theory_of_computation On the other hand, "All problems in computer science can be solved by another layer of indirection." (http://www.dmst.aueb.gr/dds/pubs/inbook/beautiful_code/html/Spi07g.html http://www.dmst.aueb.gr/dds/pubs/inbook/beautiful_code/html/...) So if that applies to this problem (after enough levels of indirection) then maybe I'm wrong.

Can we create digital logic circuitry that embodies ALL the functionality of a neuron, including interconnections (and here you have to compensate circuitry limitations that the neurons don't have) in the same size? I think you can start from there to understand current technology's limitations. I agree we will likely not be calling these things "computers", if we ever invent them.

skywhopper 13y ago
Even if you remove the size restriction and the physical limitations of manufactured circuitry, we're lacking the perfectly defined model of how a neuron actually works. We have plenty of knowledge about neurons, but nowhere near enough to simulate them realistically. You'd need to be able to account for every possible state a neuron could ever be in. But a neuron is more than just an input-output state machine, it's affected by levels of oxygen, glucose, and any number of hormones, proteins, and other chemicals in the bloodstream. An adult human's neurons are each individually shaped by their entire existence up to that point. Alcohol consumption, sun exposure, antidepressant medication, hydration levels, exercise levels. It all affects how they work. And that's just one neuron. Simulating the brain as a solution to this problem is, I think, out of the question.
- platz 13y ago
  Defining a computer in terms of transistors and logic gates is analagous to defining a brain in terms of neurons and synapses. You arbitrarily impose limits in the definition of a computer and lift those limits in definition of a brain.
- Houshalter 13y ago
  >An adult human's neurons are each individually shaped by their entire existence up to that point. Alcohol consumption, sun exposure, antidepressant medication, hydration levels, exercise levels. It all affects how they work. Possibly, but why on Earth would you want to simulate that? Just simulate what the neuron is supposed to be doing or would be doing under ideal circumstances.
  - gnaritas 13y ago
    > Just simulate what the neuron is supposed to be doing or would be doing under ideal circumstances. We still don't know that either.
- nswanberg 13y ago
  It wasn't necessary to simulate a feather in bird's wing in order to fly. In fact, practical flight really only happened once people started taking away features observed in nature.

skywhopper 13y ago

There's a whole subfield of computer science about it: http://en.wikipedia.org/wiki/Theory_of_computation http://en.wikipedia.org/wiki/Theory_of_computation On the other hand, "All problems in computer science can be solved by another layer of indirection." (http://www.dmst.aueb.gr/dds/pubs/inbook/beautiful_code/html/Spi07g.html http://www.dmst.aueb.gr/dds/pubs/inbook/beautiful_code/html/...) So if that applies to this problem (after enough levels of indirection) then maybe I'm wrong.