Comment by qarl
8 days ago
> But would that be the limits of its capabilities? It's far from certain.
Do you agree that humans are physical systems?
My understanding is that any physical system can be evaluated to any degree of accuracy by a computer, no?
> any physical system can be evaluated to any degree of accuracy by a computer
That's an interesting hypothesis, but I don't know why you'd assume it to be true at face value. It's a bit unclear how you would even define "evaluated", given that we don't yet have a mathematical model of all of physics as we know it. [0] And then consider unknown unknowns.
> Do you agree that humans are physical systems?
Do you consider humans _with infinite memory_ as physical systems? Do you consider computers _with infinite memory_ as physical systems?
[0] https://en.wikipedia.org/wiki/Physics_beyond_the_Standard_Mo...
I agree that physics being simulated is not that easy to handwave away. That's why I mention that brains probably don't "depend" on some quantum-level behavior and a more macro view of physics could be enough. What I mean here is that while there are obviously quantum effects in play at the atomic/molecular levels, if we take the cells as a black box and replace them with statistical processes, we would probably still get a human intelligence as a result - but of course I can't prove it. As a hunch, the 100 billion neurons and their 100 trillion connections, and of course their environment (glial cells are important)'s proper Simulation is enough.
As for the infinite memory, Turing machines have this nice property that they can only visit a finite amount of memory after finite steps, no matter what. A Turing machine running for a finite time (we got this) will surely use a finite space, so being "a bit short" on infinite space is not a problem, I believe.
> given that we don't yet have a mathematical model of all of physics as we know it
Yes... but that's in the area of the big bang and black holes. My understanding is that the chemistry of the brain is very well modeled.
So, unless we find unknown physics, and unless that physics behaves differently than every other known physics, humans are computable?
Do I have that right?
Let me illustrate with an example. Are you familiar with with the Collatz conjecture? It's an example of a system with only one variable, and two simple rules. Are you certain that there exists a computer program that in finite time can compute where any given integer ends up?
Now consider throwing a ball in the air. Can you even write down the rules that each of the ball's subatomic particles obeys? How can you be certain there exists a computer program that in finite time can predict where any of the particles, for any ball, ends up?
> the chemistry of the brain is very well modeled
There are models, but the fact of those models is that they do not apply to "any degree of accuracy", as you claim.
Consider the ball thrown in the air again. Is the ball affected by what happened 100 years ago, inside of a black hole 100 light years away? Why would it not be affected by that? Or if you grant that it is affected by that, do we then need a model to predict those effects before we can "evaluate" them?
EDIT regarding the below linked blog post: Did you read the rest of my comment? Did you even read the blog post you linked to?
> We certainly don’t have anything close to a complete understanding of how the basic laws actually play out in the real world — we don’t understand high-temperature superconductivity, or for that matter human consciousness
Can you try to consider my central point before replying: Are the rules governing physical reality simpler or more complex than the Collatz conjecture? Does there exist a (theoretical) computer that can "evaluate the Collatz conjecture to any degree of accuracy"?
EDIT 2: I'm not the one moving goalposts. On what grounds are you classifying the question whether a given number ends at 1 or not for the Collaz conjecture as an "inifite" computation? It's a simple boolean question, yes or no. All you have to do is build a computer that can answer yes or no for each integer. Isn't that simpler than answering the position of each atom in the ball after the throw? Each is just a function, what makes one more infinite than the other?
Also, regarding determinism, just read this article by the same guy you linked: https://preposterousuniverse.com/blog/2011/12/05/on-determin...
> For everyday-life purposes, we can’t get around the fact that quantum mechanics makes it impossible to predict the future robustly.
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No
HEH. Well... the only other option is supernatural. Is that what you mean?
Ur computer is a physical system and some aspects of it uncomputable. You cant approximate or predict everything. Picture it as billiard balls modeling a circuit, you can’t tell whether it halts, meaning you don’t know where the balls will be.
Or a program that knocks out a bottle when it finds a counter example for whatever . U can’t tell whether it will spill the liquid.
And you have as well the problems of approximating the continuous with bits, you’ll always lose information
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