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

Quantum physics

  1. Jun 2, 2006 #1
    hi.
    Im not a physicist and i have a question about quantum physics. If you shoot electrons towards a double slit and record what happens on the otherside. If you then burn the recording without ever watching it - would the electron act as if it wasnt being observed?
     
  2. jcsd
  3. Jun 2, 2006 #2

    Meir Achuz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    How would it or you know?
     
  4. Jun 2, 2006 #3

    vanesch

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    This is up to a point a question which is interpretation-dependent (understand by that, anyone's guess is ok :smile:).

    I'll answer from the PoV of decoherence theory: the answer would then be: no, it won't make a difference. I could go in the (partly formal) mathematics of this, but it is probably simpler to see it in the following way: even if you *burn* your records, the detailled state of the remnants (smoke, ash and all that) will still be dependent on the previously recorded result. Although it is practically impossible to "undo" this scrambling, the microstate still contains the information somehow, and as such, the entanglement with the environment has not been lifted (rather on the contrary, you've made it even more of a mess by burning the record).

    The only way to really "erase" your record would be by doing a quantum interference experiment where you let your different records interfere with eachother. That's of course impossible for macroscopically registered results, just BECAUSE they already got "entangled" with the environment (the information "leaked" already, due to tiny interactions between the environment and the record, into that environment).

    At least, this is how things are seen from a PoV from environmental decoherence ; there are maybe other views on this question.
     
  5. Jun 2, 2006 #4
    thanks for the reply.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?