Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Slit Experiment vs Schrodinger's Cat

  1. Jan 4, 2007 #1
    I've always been told about how that joke about whether Schrodinger's Cat is alive or dead was merely intended to highlight the fact that "quantum fuzziness" does not scale up to macroscopic objects like a cat.

    But when we do the slit experiment and observe that the photon is detected at both A and B, then aren't we seeing the "fuzziness" extending across a macroscopic distance? (ie. the photon is jumping/spanning across the distance between A and B)

    Why is macroscopic object a no-no for showing the fuzziness, but macroscopic distance is fine for showing the fuzziness?
    Are we saying that distance doesn't count at all, when it comes to tunnelling?

    What is the probability of finding the photon anywhere in the space spanning between A and B?

    Can we say that a wave object is an object of infinitely low density, since it is supposed to be spanning across the entire universe?
  2. jcsd
  3. Jan 4, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    What do you mean when you say that "the photon is detected at both A and B"? In the double slit experiment, photons are always detected at a particular point.
  4. Jan 4, 2007 #3
    Forgive me for my rusty memory, but I thought that the Double Slit Experiment was that the same photon shows up at both detectors (at points A and B)

    I thought this is cited as proof of quantum fuzziness, so that the photon can be in 2 places at once.
  5. Jan 4, 2007 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2018 Award

    But there ARE experiments that are beginning to show "macroscopic" scale effects of superpositions. That is why the Delft and Stony Brook SQUID experiments are so important (do a search on here - a lot of water has flowed under those bridges). They showed superposition effects for at least 10^6 particles.

  6. Jan 4, 2007 #5

    Doc Al

    User Avatar

    Staff: Mentor

    No, the photon is always detected by a single detector. (Perhaps you are confusing the two slits with two detectors?)
    What it shows is that the state of the photon, as it passes through this system, must be viewed as being in a superposition of single slit states. That's the only way to correctly predict the distribution of photons arriving at the detectors.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook