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Double-slit question

  1. Jun 17, 2011 #1
    If you didn't know if the "observation" tool was on or off, could you tell if a single electron had been "observed?" Does wavefunction collapse influence the electron in any measurable way? (Besides the built-up detections on the screen.)
  2. jcsd
  3. Jun 17, 2011 #2
    on collapse the path "changes"....in my opinion

    so you could do many things in-between the slit and the detector to check on the path.....for example

    1. you could have another screen in front of the existing

    2. you could have some instrument...similar to one you had at the slits, i guess or some other...this would require some thinking....to determine the path

    3. thus you could use any of the existing methods/instruments......just have to place then before the "original' detector/screen.....

    however when the screen is telling/giving the info......why you want to know earlier?

    btw....also the detector (for example quarter wave plates, QWPs) are also telling......at the slits....
  4. Jun 17, 2011 #3
    The idea is to be able to determine if an "observation" has been made. If you could measure some difference in the electron's behavior other than the interference pattern, could you determine exactly what causes collapse?

    If the slit experiment is looking at photons, and a photon has a certain wavelength when it's fired, does collapse affect the wavelength afterwards?
  5. Jun 17, 2011 #4


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    Particles are constrained by the Heisenberg Uncertainty Principle (HUP). You cannot tell from observation of an individual particle what those constraints are.

    As to the wavelength question: the answer is "no".
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