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Eliezer_Yudkowsky comments on Configurations and Amplitude - Less Wrong

26 Post author: Eliezer_Yudkowsky 10 April 2008 07:41AM

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Comment author: Eliezer_Yudkowsky 10 April 2008 11:21:46PM 6 points [-]

Eadwacer: Accepting that we are just performing 'operations' on 'configurations', what decides which operation will be performed? Is it the configuration of the incoming photon? Is it some magical (i.e.quantum) property of a half of a silver?

Amplitude flows to both end configurations, every time. That is the law of the amplitude flows. It is not one or the other.

Sebastian: Any complex number? I.e. you're invoking an uncountable infinity for explaining the lowest known layer of physics? How does that fit in with being an infinite-set atheist - assuming you still hold that position?

Infinite set atheism is not part of standard physics. Probably the best hope for reconciling infinite set atheism with a continuous universe is some equivalent of holographic theory that bounds the total information, meaning, you could always describe a wavefunction with some finite number of bits. I doubt I'm going to go into that. 'sides, my infinite set atheism could simply be wrong.

Jeremy: I was a little disturbed when you offered up the experiment that allowed us to reject the hypothesis about a half-mirror changing each time it reflects a photon or lets one through. How do we know there aren't other experiments that could discredit the amplitude hypothesis? I'm sure there's a good answer, but don't expect me to take too much on faith.

Obviously, real physics is based on a hell of a lot more experiments narrowing things down than just the ones I'm describing here. This is not the evidence. This is just here to help you interpret what the real evidence is evidence for. To see how the theory was nailed down historically by replicable experiments, you would have to read real physics books. This series is not about presenting the full evidence for QM as a hypothesis, it is about rendering the hypothesis itself non-confusing. This is my ambitious goal.

Comment author: wobster109 10 April 2011 07:00:56PM 2 points [-]

I'm sorry; I'm still a bit confused by this. "Amplitude flows to both end configurations every time," so when a single photon is fired (as in figure 1), I agree that the amplitudes of A->1 and A->2 are both 1. Does that mean both detectors click? (I was under the impression that only one detector would click.)

Comment author: lasagnaman 19 April 2011 10:04:35PM 5 points [-]

"The detector" is not a machine for "measuring the amplitude". In fact, we have no way of "measuring the amplitude". The only tool we have "measures the ratios of the squares of the amplitudes", and that tool is this: "run the simulation a bunch of times and compute the ratio of detections at 1 to detections at 2".