On Friday, October 18, 2019 at 5:18:35 AM UTC-5, Bruce wrote: > > On Fri, Oct 18, 2019 at 8:16 PM Philip Thrift <[email protected] > <javascript:>> wrote: > >> On Friday, October 18, 2019 at 1:36:33 AM UTC-5, Philip Thrift wrote: >>> >>> On Thursday, October 17, 2019 at 6:05:00 PM UTC-5, Brent wrote: >>>> >>>> On 10/17/2019 2:35 PM, Bruce Kellett wrote: >>>> >>>> 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. >>>> >>>> >>>> In Carroll's version of the experiment, which has been performed >>>> arXiv:quant-ph/9903047 v1 13 Mar 1999, the experimenter who arranged that >>>> each electron has its welcher weg recorded by a spin UP (left slit) or >>>> spin >>>> DOWN (right slit) particle does, at the end of the experiment, knows >>>> there's a record of which slit each electron went thru, and he can sign an >>>> affadavit that says that information is known. But he doesn't know it >>>> *consciously*; it's recorded by all the spin particles, but not in his >>>> memory that he can bring to consciousness. We know what happens if he >>>> signs such an affadavit or if he doesn't, it's the same: if the recording >>>> spin particles are measured in a left/right basis the information is >>>> erased >>>> and the interference pattern can be discerned by considering only >>>> particles >>>> that measured left or only those measuring right. >>>> >>>> So Deutsch was proposing to test whether the* conscious *AI which >>>> could have the recording particles as part of it's memory and presumably >>>> be >>>> conscious of the up/down spins before they were erased would produce a >>>> different result. >>>> >>>> But I wonder what happens in Carroll's experiment if, after measuring >>>> in the left/right basis and noting that two different interference >>>> patterns >>>> can then be discerned by considering either those due to left spin >>>> recording particles or considering right spin particles, one measures the >>>> recording particles again in the up/down basis. The overall pattern is >>>> the >>>> same, it's just that you've relabeled spots on the screen according to >>>> whether the second measurement of recording particles assigned them to UP >>>> or to DOWN. Now you can consider the subset labeled UP (or DOWN). This >>>> should be a superposition of ensembles randomly selected from the left and >>>> right ensembles and in that case would not show an interference >>>> pattern...but the information has certainly been erased (twice)? >>>> >>>> Brent >>>> >>> >>> >>> >>> So, in the end, it seems that reading Carroll's book is a huge waste of >>> time after all, if his "explanation" leads to confusion. >>> >>> @philipthrift >>> >> >> >> e.g. What Sean proposes is a middle decoherence [from his blog]: >> >> The trickiness relies on the fact that by becoming entangled with a >> single recording spin rather than with the environment and its zillions of >> particles, >> >> *the traveling electrons only became kind-of decohered*. >> >> With just a single particle to worry about observing, we are allowed to >> contemplate measuring it in different ways. If, as in the conventional >> double- slit setup, we measured the slit through which the traveling >> electron went via a macroscopic pointing device, we would have had no >> choice about what was being observed. True decoherence takes a tiny quantum >> entanglement and amplifies it, effectively irreversibly, into the >> environment. In that sense the delayed-choice quantum eraser is a useful >> thought experiment to contemplate the role of decoherence and the >> environment in measurement. >> >> >> In terms of Many Worlds, it sounds like a Middle World. >> > > Even in Sean's analysis it is clear that delayed choice has nothing to do > with many worlds: you get the same analysis in single world or collapse > theories, such as GRW. > > Bruce >
It seems his book is pointless then. @philipthrift -- 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/81bb8553-bd67-43a3-8a79-7cade466ee2c%40googlegroups.com.
