5 ms·
I fail to see the connection. No, a computer simulation can never predict exactly what a physical system will do, even in the case of a single particle, due to
by TheEzEzz 16y ago
I fail to see the connection.
No, a computer simulation can never predict exactly what a physical system will do, even in the case of a single particle, due to quantum uncertainty. But so what? If I took out one of your neurons and replaced it with an identical neuron, that new neuron wouldn't do exactly the same thing, again due to quantum uncertainty; nonetheless, its long term behavior would be essentially identical and you, as a person, would be no different.
That is, neurons and brains are classical objects, essentially immune to the underlying uncertainty they're built on.
- cageface 16y agoThat is, neurons and brains are classical objects, essentially immune to the underlying uncertainty they're built on. Absolutely not. Prigogine's work demonstrates that systems far from thermodynamic equilibrium (of which all living systems are an example) are intractably non-deterministic. The issue isn't the underlying quantum uncertainties, it's the macro-uncertainties of the higher-level system. In other words, you won't predict the behavior a neuron by modeling the underlying physics. You have to learn to model the macro behavior in a statistical way.
- TheEzEzz 16y agoI didn't mean to suggest that quantum effects were the only source of uncertainty. If I've got a cubic meter of pure water, I can slosh it around and observe all sorts of interesting effects. I can then model that cubic meter of water with another cubic meter. That second cube won't behave identically. A cubic meter of water has a very high Reynolds number and can have considerable chaotic turbulence (chaotic in the classical sense, not quantum). The exact motion of the water simply won't be the same, no matter how precisely you mimic the 'input' into the system (forced motion of the cube, for instance). Nonetheless, the second cube is a fantastic way to understand the first cube, and in some way is qualitatively identical, even when the specific motions aren't replicated exactly. This is exactly the same for computational simulations of the fluid. Of course they can't predict chaotic behavior, but for all intents and purposes they can be just as useful as having that second cube of water. Likewise, a computer simulation of a neuron may never exactly predict what a real neuron will do. Just like one neuron can never exactly predict what another neuron will do. Just like one bucket of water can never exactly mimic another. But who cares?
- cageface 16y agoYou're comparing two very different things here though. One bucket of water is substantially like another just as one brain is like another. A brain and a computer model of a brain are two very, very different things, with completely different meta-properties.
- TheEzEzz 16y agoYes, but what I'm pointing out is that what you are complaining computers fail to have, other physical systems also fail to have! Even a second bucket of water can't predict the first bucket of water! Thus, the fact that a computer can't either is sort of insubstantial to the question of a simulation's utility, no?
- cageface 16y agoThe essential point is that you can't model the behavior of a non-equilibrium system by modeling its constituent elements, which is what Kurzweil claims. That no two non-equilibrium systems are exactly alike seems to me a different question.