On Thu, Oct 17, 2019 at 11:41 PM John Clark <[email protected]> wrote:
> On Wed, Oct 16, 2019 at 7:53 PM Bruce Kellett <[email protected]> > wrote: > > *> The quantum erasure-delayed choice experiments that have been done,* >> > > True. > > >> * and discussed by Carroll (in his book and on his blog)* >> > > True. > > * > are entirely equivalent to Deutsch's thought experiment.* >> > > Bullshit. Where is the intelligent quantum computer? Where is the signed > document saying the mind has observed each and every photon and knows which > slit each photon went through but not mentioning which slit that is? Where > is the fact that the very last step in Deutsch's experiment is not erasing > the which way information but is looking at the developed photographic > plate? > I see, Deutsch was testing the idea that it was consciousness that collapsed the wave function. But, apart from a few flirtations with the idea, none has ever taken that seriously. It is certainly not part of the Copenhagen Interpretation. The Only place I know of that idea being worked out is in the SciFi novel "Quarantine" by Greg Egan. *> The decision to erase or not erase the welcher weg information until >> after the photons have hit the screen was a central feature of these >> experiments* >> > > *NO!!* Deutsch made it clear you erase the which way information AFTER > the photons have passed the slits but BEFORE the photons hit the screen! I > know this for a fact because 30 years ago when I first heard about his idea > I specifically asked him about this very point and he said the erasure must > be BEFORE anything hits the screen. > Deutsch may have thought it important, but it is not. It is reason is similar to the need to test EPR correlations with the measurements at space-like separations -- given SR, there can be no signal informing one observer of the other's results. In the quantum earless case, if you erase or not the welcher weg information 'before' the signal photon hits the screen, then presumably some, presently unknown physics, could send this information to the screen and influence the result there. The reason for erasing or not *after* the signal photons hit the screen is to eliminate this possibility -- any signal to the screen would have to be backwards in time. Although some suggested this possibility, it has never been taken seriously. *>Explain why the experimenters took trouble to do it *after* the photons >> hit the screen!* >> > > After? Took the trouble? After would be easy, and pointless. It is much > more difficult to erase the which way information *after* the photons hit > the slits but *before* they hit the screen, it would also be far more > informative. > I think you have misunderstood the experiments. The interference pattern is present if the welcher weg information is erased, whether the erasure takes place before or after the photons hit the screen. If the information is not erased, no interference pattern is seen, even if the idler photons drift off to infinity. * > Deutsch was simply wrong when he thought that his experiment would >> "prove" the existence of many worlds.* >> > > Actually Deutsch didn't say that, he said his experiment would test Many > Worlds not prove it correct. > OK. But the alternative that Deutsch seems to have been testing was that only a conscious observer could collapse the wave function. As I have said, this has never been a serious scientific position. When the exparament is actually performed for all I or Deutsch knows it > could prove that the Many Worlds idea is dead wrong. I've already told you > what my best guess on the outcome so what is your prediction? When that > photographic plate is developed will there be interference bands on it or > not? > If the welcher weg information is quantum erased, then there will be an interference pattern, whether or not it is a conscious observer who is erased. Bruce -- 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/CAFxXSLSg8Boc_oZe3KSOzQa%3DcN5qbZqaEU4KLni4Rw76%2B4s2rg%40mail.gmail.com.
