On Wed, Oct 23, 2019 at 12:22 AM John Clark <[email protected]> wrote:
> On Mon, Oct 21, 2019 at 6:07 PM Bruce Kellett <[email protected]> > wrote: > > >> That statement is worse than false, you're talking logical nonsense. >>> The photograph itself contains which way information, if the photo has no >>> interference pattern then you know the photon went through one and only one >>> slit, and if it does have a interference pattern then you know the photon >>> went through both slits. So if you have the ability and really and truly >>> want to destroy the which way information *AFTER* the photon hits the >>> photographic plate (or screen) then you MUST destroy the photograph too and >>> do so before anybody looks at it. In 1801 Thomas Young was not a fool and >>> that's why he had no desire to destroy his screen *BEFORE *he looked at >>> it, and that's why he saw a interference pattern; but it's true if he had >>> he would have not seen a interference pattern, he would not see anything at >>> all because there would be no screen to look at because he destroyed it. >>> >> > *> I quote from the Xiao-song Ma et al. paper (Zeilinger group): "The >> authors proposed to combine the delayed-choice paradigm with the quantum >> erasure concept. Since the welcher-weg information of the atoms is carried >> by the photons, the choice of measurement of the photons -- either >> revealing or erasing the atoms' welcher-weg information -- can be delayed >> until 'long after the atoms have passed' the photon detectors at the double >> slit.* >> > > Bruce.... it clearly said "*the photon detectors at the double slit*", > and that detector, the one right at the double slit, is the very thing that > produces the which way information that you may or may not erase! > As usual, your basic dishonesty is revealed by the fact that you have deleted the all-important following sentence: "The later measurement of the photons 'decides' whether the atoms can show interference or not even after the atoms have been detected." I have not confused the 'welcher-weg' photons with the atoms that pass the slits and show interference or not. Ma is describing an earlier experiment by Scully et al. which did not use the photon down-conversion that Ma et al. used. So Scully et al. detected the passage of atoms through the slits by using photons. Subsequent detection of the photons could reveal welcher-weg information, but that could be done long after the atoms hit the screen and showed interference or not. You should read more carefully before you jump in and accuse others of not understanding the situation. Bruce > You're confusing the photon detector that is directly at the slit, with > the far distant interference detector which could be a photographic plate > or a screen or electronic device; that second detector will see or not > see a interference pattern depending on if the which way information that > the first detector has produced has been erased or not. And yes, the > decision to erase or not to erase the which way information could be > delayed for a billion years after it passed the first detector provided the > two detectors were a billion light years apart. > -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLTxBzEVBfbgELCny3DJtOPj9bg13%3DA2v5WQXS1DUT7v_Q%40mail.gmail.com.
