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Caution: may-be Rumor

  1. Jul 30, 2008 #1
    I heard that if a measuing device is turned off, but is put into a position that, if turned on, would still be able to measure.. that this will still turn a wave into a particle
  2. jcsd
  3. Jul 30, 2008 #2
    Unless you specify what you are talking more precisely, it does not seem very likely that this makes sense at all. At least it does not to me. What do you mean by turn off ? If you have an optical lens, you can't turn it off. If you have a magnetic field, most probably it's created from a current you can switch off. If you have a semiconductor photodetector, it does not matter whether voltage is off or on when it comes to collapsing a photon's wave function.
  4. Jul 30, 2008 #3
    how many differerent ways are there to try and measure a photon?
  5. Jul 30, 2008 #4
    As many as one can think of I guess. How many materials can you build out of Mendeleev table ? Do you count measuring a photon with water different from measuring it with vapor or from ice ?
  6. Jul 30, 2008 #5
    okay, so with the semiconductor photodetector.. what is that exactly?

    did you say that even if its turned off, that the wave still turns/collapses into a particle?
  7. Jul 30, 2008 #6
  8. Jul 30, 2008 #7
    lol dont assume I know what you do, im not faking humility i really am this stupid

    basically im trying to find out if its something emitted from the (or a) device which causes the wave to collapse into a particle

    the "essence" of the rumor is that even when the (or a) device isn't currently emitting something causing the wave to warp back to a particle.. that it still causes the collapse

    began thinking about these things a month ago please be patient
  9. Jul 30, 2008 #8
    Well, maybe I have seemed overreacting : I answer while it compiles, and there is nothing worse than a shared library which should load but does not :cry: Sorry if I seemed rude.

    BTW, stupidity is very different from ignorance :wink:

    Formulated this way, the question becomes trickier. If there is any interaction whatsoever between the photon and the device, energy needs to be conserved. Ultimately, your photon hits an atom, maybe inside a molecule, but this atom will certainly reach an unstable excited state and indeed, emit something. However, if this emitted "thing" finally turns into phonons in a crystal, you have merely heated your device. Does it count as "emitting" ? You could say, yes, the heated device will emit (IR) radiation, that is a very long way to scatter a photon !
  10. Jul 30, 2008 #9
    As far as I know, there is nothing that is emitted by anything that goes up to a photon, says "Aha! I got you!" and makes its wave-function collapse.

    The only way we detect photons is by them hitting something else and us seeing the aftermath.
  11. Jul 30, 2008 #10
    Us seeing the aftermath. The photon carries an energy which has not been stored in a single atom after the photon has been absorbed. The atom would wait for you to check whether it has been excited ? At the very least you have one single Compton scattering.
  12. Jul 30, 2008 #11
    Sometimes I wish I was a moderator.
  13. Jul 30, 2008 #12
    • Please comment on the physics
    • Should not it be "I wish I were" (this is a true question)
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