LESSWRONG
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Configurations and Amplitude
Andrew320

The prediction for what happens when you block the B to D path is wrong. We have three final configurations, not two as in the above.

  • From the configuration "A photon going from B to D", with original amplitude (1 + 0i) o Amplitude of (1 + 0i) * 1 = (1 + 0i) flows to "Block with absorbed photon".
  • From the configuration "A photon going from C to D", with original amplitude (0 + -i) o Amplitude of (0 + -i) i = (1 + 0i) flows to "A photon going from D to F" o Amplitude of (0 + -i) 1 = (0 + -i) flows to "A photon
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1wizzwizz4
I think Eliezer meant "the block absorbs the photon, and then destroys the universe". It's a magical block that, instead of absorbing photons, renders it impossible for them to pass it. If it's possible for the block to absorb the photon, then I think you got the answer wrong. Eliezer was cheating a bit with his calculations, ignoring unitarity, which was okay because everything was growing by the same constant factor. Taking into account the block, you have to start paying attention to unitarity. (See GreedyAlgorithm and [anonymous]'s comments immediately above yours.) I think this means that the half-silvered mirrors multiply by i√2 and 1√2, and hence there's ½ probability the photon will hit the block and ¼ for each of the detectors detecting a photon.
Circular Altruism
Andrew350

It seems a lot of people are willing to write off minimal discomfort and approximate that to 0 discomfort, I don't think thats fair at all.

If we are talking in terms of this 'discomfort' lets start out with two sets of K people out of a population of X >>> K people, with each set having the same 'discomfort' applied to them each, set A and set B. One set must bear with the discomfort, which set should we pick?.

Clearly at the start, both are defined to be the same. So we then double the number in set A while halving their discomfort.

One way to defi... (read more)

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