On Wed, Nov 6, 2019 at 10:20 AM Alan Grayson <[email protected]> wrote:
> On Tuesday, November 5, 2019 at 4:10:21 PM UTC-7, Bruce wrote: >> >> On Wed, Nov 6, 2019 at 9:49 AM Alan Grayson <[email protected]> wrote: >> >>> On Tuesday, November 5, 2019 at 1:11:21 PM UTC-7, Brent wrote: >>>> >>>> On 11/5/2019 9:21 AM, smitra wrote: >>>> > On 05-11-2019 02:53, Alan Grayson wrote: >>>> >> IIUC, as the temperature rises, interference in the double slit C60 >>>> >> experiment declines, and eventually disappears. I don't think this >>>> is >>>> >> really a which-way experiment because the interference disappears >>>> >> whether or not which-way is observed. How does this effect the >>>> >> collapse issue? Usually, IIUC, when interference ceases to exist, it >>>> >> implies collapse of the wf. So, is the C60 double slit experiment >>>> >> evidence for collapse of the wf? TIA, AG >>>> > >>>> > >>>> > Consider the C60 moving through one or the other slit and then ending >>>> > up at some spot x on the screen. If the state of the rest of the >>>> > universe when the C60 takes on slit is |A(x)> and it is |B(x)> if >>>> > another slit is taken, then the interference pattern locally at spot >>>> x >>>> > on the screen will be proportional to Re[<A(x)|B(x)>]. So, if there >>>> is >>>> > perfect which way information for C60 that arrive in the neighborhood >>>> > of spot x on the screen, then the two environmental states will be >>>> > orthogonal and the interference will vanish. >>>> > >>>> > In case of the experiment in a thermal environment, the C60 will >>>> > suffer collisions with photons. >>>> >>>> It's not collisions with photons from the environment. The C60s are >>>> heated in the experiment, so it is IR emission from the C60 that puts >>>> which-way information into the environment. >>> >>> >>> That's what I don't understand. If there's no detector focused on, or >>> watching the slits, >>> how can which-way information exist? All we observe is loss of >>> interference without >>> which-way information. What can we conclude from this? AG >>> >> >> I thought I had explained that in my first post on this matter. If the IR >> photon wavelength is short enough, detecting that photon enables one to >> determine which path the C60 followed, or which slit it went through. >> > > Amazing if true. I assume the photon is emitted in random directions and, > moreover, there's no observation of the slits. If so, how could this > determine which-way? AG > Simply by localizing which path the atom followed. Elementary, my dear Watson. As the C60 atoms are heated up, the IR wavelengths become shorter, and we >> can determine which slit for a greater proportion of the photons. Hence the >> interference disappears gradually as the temperature increases. We do not >> even have to detect the IR photons -- their information is in the >> environment, and that is sufficient decoherence for the interference to >> vanish. >> > > This I previously understood. But what is the big picture take-away from > this phenomenon? AG > Quantum mechanics is wonderful! 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/CAFxXSLTbkqf_DrUgCtRq-Yctk3pH5cP3L8p-tt77NMYOigX_PA%40mail.gmail.com.
