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

Schrödinger's Cat, uncertainty, and observation question

  1. Jun 22, 2014 #1
    First of all, from what I've read the descriptions of an observation or measurement in Quantum Mechanics have been quite vague. Since the word measurement is used alternatively I am going to assume that this includes all types of measurements, which brings me to a question. If the box Schrödinger's cat was in was not lead lined (And we assume the source is not an Alpha emitter as the box would likely block it) would one be able to use a Geiger counter to detect if decay had occurred or would this take the cat out of superposition, thus making it either dead or alive?
     
  2. jcsd
  3. Jun 22, 2014 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Yes. Any way of "looking inside the box" counts.
    The idea of the thought-experiment is that the experimenter is able to choose when he looks.
     
  4. Jun 22, 2014 #3

    bhobba

    User Avatar
    Science Advisor
    Gold Member

    Simon is correct.

    But please understand according to the standard Copenhagen interpretation QM is a theory about observations that appear in an assumed common sense classical world. In Schrodenger's Cat that observation occurs at the particle detector. Everything is common sense classical from that point on. The cat is alive or dead period. It makes no difference if its observed or not.

    The purpose of Schroedinger's Cat was to illustrate a issue with Copenhagen. Since QM is a theory about observations in an assumed classical world and QM is the fundamental theory that is supposed to explain that world - well it obviously will find that a bit hard. It doesn't invalidate Copenhagen, but its a blemish. What is needed is a fully quantum theory of measurement.

    A lot of progress has been made to that end:
    http://www.ipod.org.uk/reality/reality_decoherence.asp [Broken]

    But without going into the details a few issues still remain eg the so called factoring problem.

    Thanks
    Bill
     
    Last edited by a moderator: May 6, 2017
  5. Jun 22, 2014 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    But yeah - a QM theory of measurement is kinda the physics form of the mind-body problem.
     
  6. Jun 23, 2014 #5
    I appreciate the excellent answers, but feel I must ask: What proposals are there for a specialised method of measuring quantum phenomena, if any?
     
  7. Jun 23, 2014 #6

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    bhobba gave you a good link for how measurement may be modeled in QM.

    In QM experiments we just use detectors and so on normally, using the theory to make predictions about the outcome. i.e. if we want to know if the cat is dead we open the box and look.
     
  8. Jun 23, 2014 #7

    bhobba

    User Avatar
    Science Advisor
    Gold Member

    Last edited by a moderator: May 6, 2017
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Schrödinger's Cat, uncertainty, and observation question
  1. Schrödinger's cat (Replies: 33)

  2. Schrödinger's cat (Replies: 5)

  3. Schrödinger's cat? (Replies: 37)

  4. Schrödinger's cat (Replies: 21)

  5. Schrödinger's cat (Replies: 18)

Loading...