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Remeasurement of a quantum system

  1. Nov 7, 2006 #1
    After making a measurement of a particular dynamical variable the wavefunction collapses into the corresponding eigenfunction. As I understand when the variable is then measured again the results and relative probabilities of eigenvalues are exactly the same as before. I don't understand why they are the same as before. What happens to the wavefunction?
  2. jcsd
  3. Nov 7, 2006 #2
    I think it slowly starts spreading out again.
  4. Nov 7, 2006 #3
    ok. Why does it spread out though? Is there a reasoning behind why the eigenvalues will be the same when another measurement is made. There was a question in a book that kind of asked for an answer to this but I can't work out why?
  5. Nov 7, 2006 #4
    Information. Start out with a state described by an eigenfunction then apply the propogator to it which describes the time evolution. At a later time the probability of observing some state is proportional to the overlap integral between the initial and final state....to put it simply
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