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Can you state in a few lines what you think he should get more credit for? He's an interesting guy, a good businessman, and I enjoy reading his anecdotes, but

Can you state in a few lines what you think he should get more credit for? He's an interesting guy, a good businessman, and I enjoy reading his anecdotes, but I kinda figure he gets about the right amount of credit for his achievements. If you mean "new kind of science" for example -I think he got about what he deserved on that.

tlb 7y ago
You shouldn't judge the value of conjectures until you know whether they're true or not. Right now, we have no computable model for physics. NKS conjectures that some particular types of CA could compute our universe. If this turns out to be true, it'll be huge.
- scottlocklin 7y ago
  I dunno, I think it's pretty easy to judge the value of not easily testable wacky conjectures. I don't think much of Penrose's idea that brains are quantum gravitic computers either, and that is vastly more close to being testable, and Penrose's achievements and track record in actual science are also vastly more impressive. Putting that aside; computer guys seem to think "computability" is important in physics. I don't. The strong Church Turing thesis is an ideological idea, not a physical one. In fact, it is an ideological idea with very little evidence in its favor either in computer science or in the world of matter.
  - tlb 7y ago
    The conjecture that our universe is isomorphic to a CA is absolutely testable. When we find a CA that behaves just like the universe, we'll know it's true. If we find a completely different way of computing it that doesn't map to a CA, we'll know it's false. Computable physics would be extremely useful. Even with coarse approximations you can only integrate the Schrödinger equation among hundreds of particles. So you can't do accurate computational biochemistry except maybe one small molecule at a time.
    - schwurb 7y ago
      > If we find a completely different way of computing it that doesn't map to a CA, we'll know it's false. This is wrong. You would have to additionally prove that the other thing is the only alternative. Also, CA is not testable in the sense that the theory of relativity is testable. The latter makes measurable predictions that can be satisfied, the former does not. I can imagine any model - unicorns and fairies included - and say that is behaves like the universe. The only way to falsify my claim is to empirically contradict one of my claims. NKS does not put forth such claims. Not the kind you would build a new CERN for.
      - tlb 7y ago
        A CA model of physics would certainly make measurable predictions, probably including some surprising ones that would suggest experiments to confirm them.
        schwurb 7y ago
        Where do you take your certainess from? If even Stephen Wolfram could not produce such predictions, then I doubt anyone else could. In all likelyhood, it is just not a good physical model.
      - api 7y ago
        > This is wrong. You would have to additionally prove that the other thing is the only alternative. A CA theory of physics would just be math, right? Wouldn't it end up being isomorphic with some mathematical representation, albeit perhaps easier to understand or evaluate in its CA form?
        tlb 7y ago
        Currently, we only know continuous mathematical models of physics. A CA model would be discrete, so not isomorphic to anything we know.
        7y ago
  - feanaro 7y ago
    > I dunno, I think it's pretty easy to judge the value of not easily testable wacky conjectures. Can you describe the process you use to easily judge the value of such conjectures? I'm at a loss of how that would be done since, even though a conjecture might not be testable easily, it might still end up being true. Even if not completely true, it might in some sense be close enough to inspire new ways of thinking that ultimately lead to the correct solution. For this reason, I'm wary of premature dismissal of "wacky" ideas. > Putting that aside; computer guys seem to think "computability" is important in physics. I don't. Taking a step back, the very ability to realize computational systems in physical systems seems very peculiar and interesting in itself, in the same way that noticing how peculiar it is that mathematics is able to describe such a large portion (all?) of physics. It then seems natural to ask oneself whether any physical system could then be considered to model some computation, which would make the connection bidirectional. I do not consider this observation to be that ludicrous nor exclusive to the computer guys.

tlb 7y ago

You shouldn't judge the value of conjectures until you know whether they're true or not. Right now, we have no computable model for physics. NKS conjectures that some particular types of CA could compute our universe. If this turns out to be true, it'll be huge.

scottlocklin 7y ago
I dunno, I think it's pretty easy to judge the value of not easily testable wacky conjectures. I don't think much of Penrose's idea that brains are quantum gravitic computers either, and that is vastly more close to being testable, and Penrose's achievements and track record in actual science are also vastly more impressive. Putting that aside; computer guys seem to think "computability" is important in physics. I don't. The strong Church Turing thesis is an ideological idea, not a physical one. In fact, it is an ideological idea with very little evidence in its favor either in computer science or in the world of matter.
- tlb 7y ago
  The conjecture that our universe is isomorphic to a CA is absolutely testable. When we find a CA that behaves just like the universe, we'll know it's true. If we find a completely different way of computing it that doesn't map to a CA, we'll know it's false. Computable physics would be extremely useful. Even with coarse approximations you can only integrate the Schrödinger equation among hundreds of particles. So you can't do accurate computational biochemistry except maybe one small molecule at a time.
  - schwurb 7y ago
    > If we find a completely different way of computing it that doesn't map to a CA, we'll know it's false. This is wrong. You would have to additionally prove that the other thing is the only alternative. Also, CA is not testable in the sense that the theory of relativity is testable. The latter makes measurable predictions that can be satisfied, the former does not. I can imagine any model - unicorns and fairies included - and say that is behaves like the universe. The only way to falsify my claim is to empirically contradict one of my claims. NKS does not put forth such claims. Not the kind you would build a new CERN for.
    - tlb 7y ago
      A CA model of physics would certainly make measurable predictions, probably including some surprising ones that would suggest experiments to confirm them.
      - schwurb 7y ago
        Where do you take your certainess from? If even Stephen Wolfram could not produce such predictions, then I doubt anyone else could. In all likelyhood, it is just not a good physical model.
    - api 7y ago
      > This is wrong. You would have to additionally prove that the other thing is the only alternative. A CA theory of physics would just be math, right? Wouldn't it end up being isomorphic with some mathematical representation, albeit perhaps easier to understand or evaluate in its CA form?
      - tlb 7y ago
        Currently, we only know continuous mathematical models of physics. A CA model would be discrete, so not isomorphic to anything we know.
        7y ago
- feanaro 7y ago
  > I dunno, I think it's pretty easy to judge the value of not easily testable wacky conjectures. Can you describe the process you use to easily judge the value of such conjectures? I'm at a loss of how that would be done since, even though a conjecture might not be testable easily, it might still end up being true. Even if not completely true, it might in some sense be close enough to inspire new ways of thinking that ultimately lead to the correct solution. For this reason, I'm wary of premature dismissal of "wacky" ideas. > Putting that aside; computer guys seem to think "computability" is important in physics. I don't. Taking a step back, the very ability to realize computational systems in physical systems seems very peculiar and interesting in itself, in the same way that noticing how peculiar it is that mathematics is able to describe such a large portion (all?) of physics. It then seems natural to ask oneself whether any physical system could then be considered to model some computation, which would make the connection bidirectional. I do not consider this observation to be that ludicrous nor exclusive to the computer guys.