JGWeissman comments on Open Thread: September 2009 - Less Wrong

2 Post author: AllanCrossman 01 September 2009 10:54AM

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Comment author: JGWeissman 01 September 2009 07:26:29PM 0 points [-]

We have quantum mechanics but quantum computers have been late in coming, suggesting that our universe would be difficult to simulate.

Quantum computers are computers which use quantum superposition for parallel processing, and are not required for simulating quantum mechanics. And our "classical" computers do in fact take advantage of quantum mechanics, as classical physics does not allow for solid state transistors.

Comment author: [deleted] 01 September 2009 10:50:21PM 0 points [-]

It seems that quantum computers are required for simulating quantum mechanics in sub-exponential time, though.

Comment author: JGWeissman 02 September 2009 04:17:50AM 1 point [-]

When discussing asymptotic algorithmic complexity, you should specify the varying parameter of problem complexity.

Comment author: pengvado 02 September 2009 05:17:47AM 0 points [-]

The usual default parameter is number of bits it takes to write down the problem. It could also be number of particles. Either one works in this case.

Comment author: JGWeissman 02 September 2009 09:16:54PM 0 points [-]

What quantum algorithm for simulating quantum mechanics takes sub-exponential time with respect to the number of particles?

Comment author: pengvado 02 September 2009 11:31:45PM 0 points [-]

I didn't have a particular algorithm in mind when I said that, but since you ask I went and found this one.