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

Wave function collapse for Schrödinger's cat

  1. May 6, 2012 #1
    I have what is probably a very basic question about the Schrödinger's cat thought experiment. As I understand it, in order for the counter tube to break and release the deadly poison, the Geiger counter must measure whether or not an atom decays. So, why doesn't that measurement collapse the wave function? And, if that measurement isn't enough, why wouldn't the cat's observation of poison or no poison collapse the wave function?

    And if I'm incorrect about the Geiger counter being a measurement, then would I be correct to assume that by the same logic, if you conducted a double slit experiment, and you put photon detectors by both slits, but you never actually look at the wall on the other side, that Schrödinger would suggest that the photon detectors by themselves were insufficient to collapse the wave function?

    I get that Schrödinger used this thought experiment as a reductio ad absurdum, but I don't understand why the Copenhagen interpretation would require the cat to be in some undead quantum state.
  2. jcsd
  3. May 7, 2012 #2
    The point of this representation is to look past the two possible results of the experiment (Observed and unobserved) and realize what the true "Quantum Reality" is. The results of the experiment differ based on the circumstances but the statement that the cat is both alive and dead is true before the experiment actually happens.
  4. May 7, 2012 #3
    We are not sure what constitutes a measurement, at least yet.

    All that happens is the photon becomes entangled with the photon detectors, therefore continuing to predict a superposition of left and right slit.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook