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Why dont air molecules cause collapse

  1. Jan 5, 2010 #1
    Hey everyone, i'm not a math or physics major. I've just read a bit about quantum physics and find it interesting. If i understand it correctly, with the two slit experiment, when you send one particle at a time through without a particle detector by the slit, it results in an interference pattern. If you put a particle detector by the slit, the particle acts like a regular ol particle. My first question is, why doesn't the particle interact with the molecules all around in the AIR. My second question is, does the particle detector send out some sort of signal that is more apt to cause the wave function to collapse? I just don't know how you get around knowledge or consciousness causing it to collapse, i would think that if a particle collapsed do to being "measured" by a measuring device....the air particles that the electron or photon or whatever is traveling through would cause the collapse. OK, and last question, cant you AIM to which slit you want the particle to go through? If someone can give me the their response in layman's terms i would appreciate it
  2. jcsd
  3. Jan 5, 2010 #2


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    They do, sometimes. See this post. See also this book. The essential difference between photons and the large molecules used in the really cool experiments discussed there is that photons don't interact as strongly with its environment (the air).

    The detector doesn't send out a signal. Knowledge and consciousness has nothing to do with it. The detector "collapses" the wavefunction because the states of the particle become entangled with the states of a system (the detector) which interacts very strongly with its environment (because it's a macroscopic system). To really understand this, you would probably have to read that book I linked to.

    You can't really aim the particles toward one of the slits, but you can block the paths leading to the other slit, or put the particle source closer to one of the slits than the other.
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