On Wed, Oct 16, 2019 at 7:47 AM John Clark <[email protected]> wrote:
> > Oh for christ sake! As I've said over and over, in Many Worlds a change, > any change, is equivalent to a measurement and it doesn't make the > slightest difference if that change involves consciousness or not. If Brent > Meeker flips a coin and it comes out heads then obviously that Brent Meeker > is not living in the world where it came out tails. In the same way if you > do the two slit experiment and the photon goes through slit A then you are > not living in the world where it went through slot B, but the 2 slit > experiment can be a little different from > the simple coin toss example. > > If after the photon makes its decision on which of the 2 slits to go > through it then hits a photographic plate then both photons in both > universes are destroyed and thus there is no longer any difference between > the two, so the universes will merge back together. So in that newly > re-merged universe there will be ambiguity about which slit the photon > actually went through which is why that photon will contribute to the > interference pattern that shows up on the photographic plate. The important > thing is that the photographic plate destroys the photon in both universes > so you could replace the plate with a brick wall and the same thing would > happen, it would just be harder to tell that something funny was going on. > > However if you had a detector next to each slit and sent information on > which slit the photon went through to your computer then there would still > be a physical difference between universes even though the photon no longer > exists in either, one universe would have computer in it with a few > magnetic spots on its disk drive indicating the photon went through slot A > but in the other universe the magnetic spots would be in a slightly > different place indicating slot B, so the universes remain different, so > they don't remerge, so there is no ambiguity in either universe, so neither > universe will see a interference pattern. > > Universes don't usually merge back together because the differences > between them usually accelerates so it's astronomically unlikely they will > ever become identical again, however a skilled experimenter can make the > change to be very small and then can gently nudge them back together. If > you got rid of the film (or the brick wall) and let the photon head out > into infinite space after it passed the slits then the universes, and you, > will split and never recombine, and so of course you will see no > interference effect. The beautiful part of the theory is that it doesn't > have to explain what an observer is and that's why a brick wall will work > just as well as a photographic plate. > I think an equivalent experiment has been done. It is the quantum eraser work of Zeilinger and associates: https://en.wikipedia.org/wiki/Quantum_eraser_experiment This also illustrates delayed choice, since the decision to erase the "welcher weg" information can be made after the photons have been recorded on the screen. Ingenious variations of this have been done using polarised photons as carriers of the "which way" information, using rotated polarisers to erase the information or not. I don't think anyone has seen many worlds emerge from these experiments. They have straightforward interpretation in any quantum interpretation. 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/CAFxXSLQsoN-4mFT47w0Lmz%3DbpweaxQoHF263npVGcLZT8c%3DGzA%40mail.gmail.com.
