Your conclusion doesn’t follow from your premises, and your second premise is false besides as others have pointed out — CPUs CANNOT simulate even classical physics exactly, and certainly not quantum physics.
But even if such a complete simulation were possible, there’s every reason to assume a CPU would lack the consciousness to experience anything. When you simulate a hurricane does the CPU get wet?
> your second premise is false besides as others have pointed out — CPUs CANNOT simulate even classical physics exactly, and certainly not quantum physics.
Both classical and quantum physics can be simulated on a classical computer, to an arbitrary degree of precision. Granted, the case in which infinite precision (if such a thing even exists in reality) is required is not simulatable on a discrete computer, but do any experts actually believe this to be the case? It's certainly not an opinion that I've seen around.
I think discussions about "can we actually get enough computing power to do this in practice" are beside the point - the discussion was about whether computers can feel in principle. If we wanted to do it in practice and were at the point where this was feasible, we'd probably engineer a CPU or co-processor more suited to the task than the general-purpose CPUs of today.
> there’s every reason to assume a CPU would lack the consciousness to experience anything.
If we are physical beings, then "consciousness" and anything else we have must be an emergent property of our physical components. If we can simulate those physical components, then this simulation will exhibit the same properties - consciousness and anything else one can attribute to us.
If our consciousness comes from non-physical properties we have (a "soul" or anything metaphysical), then sure, I'd agree with you.
> If we are physical beings, then "consciousness" and anything else we have must be an emergent property of our physical components. If we can simulate those physical components, then this simulation will exhibit the same properties - consciousness and anything else one can attribute to us.
Again, a simulation is not the thing. The map is not the territory. If consciousness truly emerges from actual physical processes of interacting brain matter (seems plausible), those _don’t exist_ in a computer simulation.
In a simulation of a brain, from what substrate could consciousness emerge? The state of the simulated brain is stored in an arbitrary subset of locations in RAM, unknown to and non-interactive with each other, along with loads of other stuff the computer is keeping track of. Do you think consciousness could emerge automatically from the state of the right subset of locations in RAM, or is it whenever a relevant value in memory is changed due to a transistor opening, or is it when the simulation computation that will result in the RAM update is happening, or is complete? Per the Chinese Room argument, would consciousness still emerge if half the operations were actually performed off-CPU by human mechanical turkers with rule books and notecards? Nothing in the abstract computation will have changed.
Consider also that physical reality runs in full parallel, while simulations on computers run serially per core. So if consciousness emerging requires the simultaneous interaction of many moving brain parts, that isn’t something that happens in a computer simulation.
> Both classical and quantum physics can be simulated on a classical computer, to an arbitrary degree of precision
Quantum physics can’t be simulated on a classical computer to an arbitrary degree of precision. Feynman didn’t think so, and he hasn’t been gainsayed yet. And classical physics is full of chaos and very sensitive to precision.
> In a simulation of a brain, from what substrate could consciousness emerge?
Exactly the same substrate as our brains are derived from: physical particles and their interactions, perfectly replicated inside the simulation. If the simulation is accurate enough, the real particles and the simulated particles behave exactly the same, hence they produce the same results.
> Do you think consciousness could emerge automatically from the state of the right subset of locations in RAM
Hard question to answer since consciousness is hard to analyse. But we can turn it around into a question whose answer is the same, with a bit of rephrasing:
Do you think consciousness could emerge automatically from the state of the right subset of particles in our physical world, or is it whenever a relevant particle state are changed due to particles interacting according to the laws of physics, etc etc
> Consider also that physical reality runs in full parallel,
We don't really know this to be the case. It looks like that to us, but that could easily be an illusion created by mechanisms we can't observe. Just as characters in a video game can't observe how their world is simulated - everything is perfectly consistent whether it was calculated in one CPU thread or several.
Or a more succinct question: why do you think a simulation of consciousness is the same as consciousness? What other simulations of things are identical with the things?
I think that a sufficiently accurate simulation of a system exhibits the same emerging properties as the system itself.
For example, if I can perfectly simulate the weather in some simple planet, all possible emerging weather phenomena for that planet (say like clouds, rain etc) will be perfectly replicated in the simulation. Similarly, if we can perfectly simulate a human body, all of the emerging human phenomena will exist in the simulation (muscle movement, nerve impulses, brain patterns resulting in consciousness etc). I don't think consciousness is fundamentally different from other physical phenomena, it's just a particularly complex example.
Another angle to think about: We can't prove that we're not living in a simulation (or can you?). So our consciousness itself might be simulated for all we know. This is not a proof that we are amenable to being simulated, but it means that disproving it is very hard or impossible.
You lost me. You think consciousness is a _physical_ phenomenon that would necessarily emerge from an accurate _simulation_ of a particle system? If it’s a physical phenomenon in reality, then just like the clouds and rain in your weather sim aren’t physical, only a simulation of consciousness will be present in your simulation.
But even if such a complete simulation were possible, there’s every reason to assume a CPU would lack the consciousness to experience anything. When you simulate a hurricane does the CPU get wet?