On Sat, Oct 19, 2019 at 5:57 PM Bruce Kellett <[email protected]> wrote
>> Because the choice to erase or not to erase is delayed until long after >> the photon has passed the slit, it could be made a billion years after it >> passed the slit, and the decision could be made one nanosecond before the >> photon hit the photographic plate, but it must be *before* or you will >> see nothing new or interesting. >> > > > Exactly what do you think that you will see in that case? and why do > you think it uninteresting? > If you decide, one nanosecond *BEFORE* the photon hits the screen, to erase the information about which slit the photon went through a billion years ago then you will always see a interference pattern, and that indicates a billion years ago the photon must have gone through both slits. But if you decide, one nanosecond *BEFORE* the photon hits the screen, NOT to erase the information about which slit the photon went through a billion years ago then you will NOT see a interference pattern and you will know that a billion years ago the photon must have gone through one and only one slit. I find that result to be so interesting and surprising that I feel no necessity to spell out why. But if the information is erased after the photon hits the screen then the results are neither interesting or surprising because it wouldn't tell us anything new we didn't discover in 1801. *>>> Yes, of course you do: you just select the subsets of photons that >>> were quantum-erased by passing the left polarizer (respectively, the right >>> polarizer) to see the interference patterns emerge from the apparent >>> no-interference blob.* >>> >> >> >> Ah Bruce.....in that case you are very obviously erasing the which >> way information BEFORE it hits the screen or photograph that you're looking >> at! >> > > *> You will have to explain that to me.* > If you place a polarizing filter oriented in the left-right direction over one slit and a polarizing filter oriented in the up-down direction over the other slit and shine a light through both slits and onto a screen you will not see a interference pattern on that screen because the filters have encoded information onto the photons about which slit they went through. However if you then place a third polarizing filter, this time oriented at a intermediate 45 degree angle, after the slits but *BEFORE* the screen then "the interference pattern emerges from the apparent no-interference" because that 45 degree filter has erased the which way information that was encoded on the photons *BEFORE* any photons hit the screen that you're looking at. > *You say you are not an expert on this.....I think that has become very > clear.....* > It's perfectly true I'm not a expert on this, but I certainly hope you're not claiming that you're different and are an expert because that would be laughable. You have demonstrated a profound lack of understanding of a basic fact that is taught in the first minute on the first day in a first course on The Delayed Choice. If you don't even understand the basic facts of the experimental setup how in the world can you hope to interpret the results? John K Clark -- 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/CAJPayv0NhKF2KbdjxaOSKJOzVvE3Bnu2vazJbt%3DpYYOuvrRDpw%40mail.gmail.com.
