On Mon, Dec 3, 2012 at 3:26 PM, meekerdb <meeke...@verizon.net> wrote:

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> > > That's where you're wrong; read the paper more carefully. If you record > the which-way the interference is lost. [...] The interference pattern > occurs *only* if the which way information is *erased* > Nope, you've got it exactly precisely backwards yet again. I quote from http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experiment:<http://en.wikipedia.org/wiki/Wheeler%27s_delayed_choice_experiment> " If the experimenters know which slit it goes through, the photon will behave as a particle. If they do not know which slit it goes through, the photon will behave as if it were a wave when it is given an opportunity to interfere with itself. " Or you don't like Wikipedia http://www4.ncsu.edu/unity/lockers/users/f/felder/public/kenny/papers/quantum.html : *" *when we don't know which slit the photons are going through, we get a wave interference pattern. When we do know which slit each photon traveled through, no interference pattern."* *Or maybe* you prefer this: *http://grad.physics.sunysb.edu/~amarch/* * "One can set up a measurement to "watch" which slit a photon goes through. It can be determined that the photon went through one slit and not the other. However, once this is kind of measurement is set up, the photons will no longer collectively produce a nice pattern of bright and dark spots. Instead they will strike the screen in one big bright spot, as if there were only one slit instead of two." Or perhaps this: http://theobservereffect.wordpress.com/the-most-beautiful-experiment/ "If one neglects to observe which slit a photon passes through, it appears to interfere with itself, suggesting that it behaves as a wave by traveling through both slits at once. But, if one chooses to observe the slits, the interference pattern *disappears*, and each photon travels through only one of the slits." * *Actually you don't need other people to tell you this you can figure this out on your own; if you only have one slit then obviously you know which slit the photon went through and there is no interference pattern. But if you have 2 closely slits then you don't know which slit the photon went through and you get a interference pattern. John K Clark * * -- You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to everything-list@googlegroups.com. To unsubscribe from this group, send email to everything-list+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.