On Wednesday, December 5, 2012 1:41:43 AM UTC-5, Brent wrote: > > On 12/4/2012 9:14 PM, Craig Weinberg wrote: > > > > On Tuesday, December 4, 2012 6:27:42 PM UTC-5, Brent wrote: >> >> On 12/4/2012 12:32 PM, Craig Weinberg wrote: >> >> >> >> On Tuesday, December 4, 2012 2:52:25 PM UTC-5, Brent wrote: >>> >>> >>> Kinda depends on what you mean by 'available'.� If the entangled >>> photon is allowed to hit a wall and be absorbed, it is only 'available' to >>> a kind of Maxwellian demon who can discern the thermal atomic motions and >>> trace them back to get which-way infomation - but the interference pattern >>> is destroyed anyway.� If the entangled photon is simply allowed to fly >>> out the window and off to infinity it is 'available' many years later to an >>> inhabitant of some extra-solar planet - and the interference pattern is >>> destroyed in our present.� >>> >> >> What if the inhabitant of the extra-solar planet catches the photon in a >> lens just like the quantum eraser? >> >> >> The interference would be destroyed.� Note that the way the experiment >> works (and necessarily so) is that the photons detected at the interference >> plane have to be post-selected to pair up with those either erased or not >> on the other leg.� So since an extra-solar observer could only catch a >> small fraction of the photons, the interference would erased in the >> corresponding small fraction of those hitting the interference plane. >> > > You could look for a temporal rather than spatial interference pattern. > That way there would be a chance that if any photons were received they > might continue to stream for long enough: > > "The latest experiment is radically different because the slits exist in > time not space, and because the interference pattern appears when the > number of electrons at the detector is plotted as a function of their > energy rather than their position on a screen. The work was performed at > the Technical University of Vienna in collaboration with physicists from > the Max Born Institute in Berlin, the Max Planck Institute for Quantum > Optics in Munich and the University of Sarajevo. > > Paulus and co-workers focused a train of pulses from a Ti:sapphire laser > into a chamber containing a gas of argon atoms. The pulses were so short > � just 5 femtoseconds � that each one contained just a few cycles of > the electric field. > > The team was able to control the output of the laser so that all the > pulses were identical. The researchers could, for example, ensure that each > pulse contained two maxima of the electric field (thatis, two peaks with > large positive values) and one minimum (a peak with a large negative > value). There was a small probability that an atom would be ionized by one > or other of the maxima, which therefore played the role of the slits, with > the resulting electron being accelerated towards a detector. If the atom > was ionized by the minimum, the electron travelled in the opposite > direction towards a second detector. > > The team registered the arrival times of the electrons at both detectors > and then plotted the number of electrons as a function of energy. The > researchers observed interference fringes at the first detector because it > was impossible to know if an electron counted by the detector was produced > during the first or second maximum. > > There was no interference pattern at the second detector because all the > electrons were produced at the same time at the minimum. However,when the > phase of the laser was changed so that there was one maximum and two > minima, interference fringes were seen at the second detector but not at > the first. �We have complete which-way information and no which-way > information at the same time for the same electron,� says Paulus. "It > just depends on the direction from which we look at it."� - > http://physicsworld.com/cws/article/news/2005/mar/02/new-look-for-classic-experiment > > > I looked at the paper. It doesn't show the detector arrangement, but from > the description I don't see that it can obtain which-way and no-which-way > for the *same* electron. >
I think that they are using two detectors on the same wave, so that each one of the twin peaks on one detector which produce no-which way interference patterns is also a single peak on the opposite detector which produces the which way no-interference pattern. It's staggered like a zipper. > > > >> >> What if the inhabitant naturally has eyes which function as quantum >> erasers? >> >> >> Those wouldn't be eyes.� The eraser focuses the photons on the same >> spot whichever slit they went through so the 'eyes' that would erase the >> information are 'eyes' that can't resolve the slits. >> > > Maybe more photoreceptors than eyes, but they can still discern light from > dark, so they could be used as eyes of a sort, especially if their brain > accumulated light-dark patterns over time...i.e. more like optical ears. > > > But if they don't detect the direction of the photon with sufficient > resolution then they won't act as erasers of the interference pattern. > Maybe it could detect a red shift? Would that be enough? I think that the term 'eraser' is fundamentally misguided. What it seems like is that we are looking at the arrow of time with a microscope, and seeing how events themselves are realized, through a conservation of semantic continuity. > > >> >> What if the inhabitant has one eye which is a quantum eraser and one >> which isn't? >> >> >> Depends on which one detects the photon. >> > > Yes, that's the point. If you don't know which one, how does the > interference pattern know? > > > 'It knows' because you have to select out the photon detections > corresponding the ones whose partner went in the detector eye in order to > see the interference. > Not sure I get that. > > > >> >> What if the inhabitant has a cat in a box with a cyanide capsule >> triggered by... >> >> >> What if you read the papers yourself. >> > > I try but find the jargon distracting. > > > I don't see any jargon.� It's just that real experiments are messier and > have more details to explain than thought experiments. > That's no excuse for omitting a clear summary of what was learned and why. Craig > > Brent > > It's amazing how much clearer Leibniz and Einstein are to read - it > seems like they are actually trying to explain something that they > understand rather than impress a peer review or grant committee. > > Craig > � > >> >> Brent >> >> -- > 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/-/NVEGbTkS4wkJ. > To post to this group, send email to [email protected]<javascript:> > . > To unsubscribe from this group, send email to > [email protected] <javascript:>. > For more options, visit this group at > http://groups.google.com/group/everything-list?hl=en. > > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2012.0.2221 / Virus Database: 2634/5437 - Release Date: 12/04/12 > > > -- 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/-/BPBygI587IsJ. 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.
