On Tuesday, December 4, 2012 1:51:55 PM UTC-5, Brent wrote: > > On 12/4/2012 8:29 AM, John Clark wrote: > > On Mon, Dec 3, 2012 at 3:26 PM, meekerdb <[email protected]<javascript:> > > wrote: > >> >> > 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. " > > > That's why you need to read the technical papers instead of Wikipedia. > The above is correct when there are just photons going through one pair of > slits. But in the Delayed Quantum Eraser experiment there are *two* > entangled photons one of which goes through slits and one of which *could > be detected and give which-way information*. The point is that if it is > not detected (flys off to infinity, absorbed in the wall,...) the > interference pattern is still destroyed. To maintain the pattern the > information in the entangled photon has to be *erased* - that's the > function of the lens. > > Loss of the interference isn't because "they do not know"; it's a > consequence of the information being "out there" - and being absorbed in a > wall still leaves it "out there". This is even clearer in the buckyball > Young's slits experiment, quant-ph/0402146v1. The interference pattern is > lost when the buckyballs are hot enough that their IR radiation is > sufficient to localize them to the slit spacing - even though nobody ever > observes or detects the IR photons. > > All those below fail to consider the relevant case too; they assume all > cases in which no experimenter measures which-way are equivalent. They > ignore the possibility that "the environment" may measure which-way but no > person does. > > Brent >
It's confusing. Can you simplify it? One photon heads toward the slits. One entangled photon heads toward the detector. (They are both entangled with each other, but I assume you mean one pair of entangled photons, not two pairs.) Is there a detector on the slits too? It seems like the point of the experiment is that the interference pattern only shows up when the ability to discern which-way is not available - which seems to me to support observer-principle type interpretations. Certainly I don't see any suggestion that there is a such thing as 'information' which is independent of some kind of sense receptivity. To the contrary: Time 6. Upon accessing the information gathered by the Coincidence Circuit, > we the observer are shocked to learn that the pattern shown by the > positions registered at D0 at Time 2 *depends entirely* on the > information *gathered* later at Time 4 and available to us at the > conclusion of the experiment. > The position of a photon at detector D0 has been registered and scanned. > Yet the actual position of the photon arriving at D0 *will be at one > place if we later learn* more information; and the actual position will > be at another place if we do > not.-http://www.bottomlayer.com/bottom/kim-scully/kim-scully-web.htm > I intentionally bolded the terms where the true nature of quantum is revealed - with the capacity to detect, 'learn', 'gather', i.e. to become informed through a sensory-motor event within the matter which makes up a physical instrument (including, but not limited to, human eyes, brains, etc). Physics is sensory-motor participation. Nothing more and nothing less. There is no such thing as 'information'. Craig -- You received this message because you are subscribed to the Google Groups "Everything List" group. To view this discussion on the web visit https://groups.google.com/d/msg/everything-list/-/xEjC88-mcZ4J. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/everything-list?hl=en.
