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Neither humans nor any physical device is Turing complete; only bounded computations can we perform. What do you mean by mechanistic? Mathematical? Deterministi

Neither humans nor any physical device is Turing complete; only bounded computations can we perform. What do you mean by mechanistic? Mathematical? Deterministic? Non-dual with no unmeasurable causes?

ncallaway 3y ago
> What do you mean by mechanistic? So, I’ve only used it in a “I understand what it means and what I mean by it” manner in the past, and I haven’t rigorously defined it for myself. I’ll do the best giving an off-the-cuff definition, but I’m sure it will have some holes and would be improved with some time spent thinking about it, or reading to crib a definition from someone else who has already put in that time. I think my definition of a mechanistic universe would be: A universe that transitions from one state to an adjacent state through a consistent set of rules. From your options: - mathematical? I’m think yes, but potentially only if “mathetics” is defined broadly. - Deterministic? I don’t think this is a requirement for a mechanistic universe. My bet would be on a deterministic universe (through an Everettian interpretation lens), but I think something can be mechanistic while being stochastic, so long as the rules determine the probabilities. That is, I would consider a computer with a true source of randomness to still be mechanistic. > Non-dual with no unmeasurable causes? Non-dual, yes. That is the primary meaning for me. “With no unmeasurable causes” is a phrasing that makes me slightly uneasy. I could imagine a situation where, if the universe is stochastic you could end up in a situation where you cannot precisely identify the specific cause for a specific event. But, I think as the spirit of this question is intended, yes.
- lanstin 3y ago
  Thanks, that all makes sense. Do you follow Sean Carroll's takes on many worlds? A very consistent philosophy of reality, and some interesting math starting to come out with space-time itself being an emergent feature of Hilbert space evolution of the wave equation (where it is constructed essentially out of varying degrees of coupling between different states). Even a paper where this sort of coupling-derived space might obey the Einstein equations.
  - ncallaway 3y ago
    I listen to his podcast, and I’m definitely partial to the many worlds interpretation, so I end up taking in a lot of his explanations of it. The work he’s doing in that area is super interesting, and sounds promising (of course, I’m getting primarily Carroll’s take on it when I hear about it, so it makes sense that it sounds promising!), but the math itself is above my head. I am super interested to see if it ends up moving the ball forward on resolving the GR/QM conflicts.
    - Vecr 3y ago
      I personally don't think it will but I guess it could, it's as good a model to start from as any. That's kind of the problem though, it's not actually better than the modern version of the Copenhagen interpretation unless you think wave function collapse is a physical event that's caused by (something in) your brain. If you think that, Copenhagen's obviously not correct, as your brain can't cause anything that it itself wasn't caused to do, because free will does not exist. If you think of wave function collapse as not a physical event and not caused by anything (except by the physics of the universe following the original state of the universe, if you don't like the idea of a block universe in configuration space), it's totally fine and is equivalent to Multiple Worlds. Don't think of the Multiple Worlds as things that physically exist either though.
kaba0 3y ago
Can we stop with this stuff? It is a 100% useless distinction, Turing machines can only ever use a fixed amount of memory, so we can run any Turing machine for as long as we want to, we can just pause it, “change the tape” to a bigger one, and continue.
- lanstin 3y ago
  Well, it's not useless mathematically. The Turing machine cannot run on all inputs with a bounded tape size. The quickly growing functions show pretty strongly that no physically incarnateable device can compute easy to specify functions on inputs less than 1000. "Turing machine" or Turing equivalence are pretty precisely defined mathematical concepts, so using them in different senses is a bit perverse; in my mind, more perverse than using literally to mean figuratively. Also, how does one change the tape in ones brain? I'd love a pensieve but those also are not physical, at least not yet. The thing I'd really like is a Turing machine where the nth transition took 1/2^n seconds, so we could run them to infinity in just two seconds.

ncallaway 3y ago

> What do you mean by mechanistic? So, I’ve only used it in a “I understand what it means and what I mean by it” manner in the past, and I haven’t rigorously defined it for myself. I’ll do the best giving an off-the-cuff definition, but I’m sure it will have some holes and would be improved with some time spent thinking about it, or reading to crib a definition from someone else who has already put in that time. I think my definition of a mechanistic universe would be: A universe that transitions from one state to an adjacent state through a consistent set of rules. From your options: - mathematical? I’m think yes, but potentially only if “mathetics” is defined broadly. - Deterministic? I don’t think this is a requirement for a mechanistic universe. My bet would be on a deterministic universe (through an Everettian interpretation lens), but I think something can be mechanistic while being stochastic, so long as the rules determine the probabilities. That is, I would consider a computer with a true source of randomness to still be mechanistic. > Non-dual with no unmeasurable causes? Non-dual, yes. That is the primary meaning for me. “With no unmeasurable causes” is a phrasing that makes me slightly uneasy. I could imagine a situation where, if the universe is stochastic you could end up in a situation where you cannot precisely identify the specific cause for a specific event. But, I think as the spirit of this question is intended, yes.

lanstin 3y ago
Thanks, that all makes sense. Do you follow Sean Carroll's takes on many worlds? A very consistent philosophy of reality, and some interesting math starting to come out with space-time itself being an emergent feature of Hilbert space evolution of the wave equation (where it is constructed essentially out of varying degrees of coupling between different states). Even a paper where this sort of coupling-derived space might obey the Einstein equations.
- ncallaway 3y ago
  I listen to his podcast, and I’m definitely partial to the many worlds interpretation, so I end up taking in a lot of his explanations of it. The work he’s doing in that area is super interesting, and sounds promising (of course, I’m getting primarily Carroll’s take on it when I hear about it, so it makes sense that it sounds promising!), but the math itself is above my head. I am super interested to see if it ends up moving the ball forward on resolving the GR/QM conflicts.
  - Vecr 3y ago
    I personally don't think it will but I guess it could, it's as good a model to start from as any. That's kind of the problem though, it's not actually better than the modern version of the Copenhagen interpretation unless you think wave function collapse is a physical event that's caused by (something in) your brain. If you think that, Copenhagen's obviously not correct, as your brain can't cause anything that it itself wasn't caused to do, because free will does not exist. If you think of wave function collapse as not a physical event and not caused by anything (except by the physics of the universe following the original state of the universe, if you don't like the idea of a block universe in configuration space), it's totally fine and is equivalent to Multiple Worlds. Don't think of the Multiple Worlds as things that physically exist either though.

kaba0 3y ago

Can we stop with this stuff? It is a 100% useless distinction, Turing machines can only ever use a fixed amount of memory, so we can run any Turing machine for as long as we want to, we can just pause it, “change the tape” to a bigger one, and continue.

lanstin 3y ago
Well, it's not useless mathematically. The Turing machine cannot run on all inputs with a bounded tape size. The quickly growing functions show pretty strongly that no physically incarnateable device can compute easy to specify functions on inputs less than 1000. "Turing machine" or Turing equivalence are pretty precisely defined mathematical concepts, so using them in different senses is a bit perverse; in my mind, more perverse than using literally to mean figuratively. Also, how does one change the tape in ones brain? I'd love a pensieve but those also are not physical, at least not yet. The thing I'd really like is a Turing machine where the nth transition took 1/2^n seconds, so we could run them to infinity in just two seconds.