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Sean Carroll's view of the atom

  1. Aug 13, 2012 #1
    Here's a pic from Sean Carroll's lectures on Dark Matter and Dark Energy available through the Teaching Company:


    I just want to double check, there are two types of atoms, if I understand the delayed choice experiment correctly, just the knowledge that you can detect the atom transforms it from occupying a probability cloud (wave-like) where the electron does not really occupy a point in space to occupying a definite place (particle-like). I'm pretty sure I'm right and I don't understand why Carroll didn't throw in a few quantum mechanical slogans such as knowing that you can detect an atoms transforms it from x to y.
  2. jcsd
  3. Aug 13, 2012 #2

    Simon Bridge

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    That would not be correct - those are not two different types of atoms, but different ways of looking at electrons. Just like "heads" and "tails" are not two different kinds of coins.

    The picture is non-physical, representative only. Electrons are not observed to orbit like that. It is probably intended to illustrate the basic components of the Bohr model.
  4. Aug 13, 2012 #3


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    Which lecture # (and if you know, at what time point in the lecture) ?
  5. Aug 13, 2012 #4
    Do you have the lecture series? It's from the first lecture probably around the 10the minute, give or take 5 minutes.
  6. Aug 13, 2012 #5


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    Yeah, I'll take a look
  7. Aug 13, 2012 #6


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    He's just using the old Bohr model to give an introductory talk about the PARTS of atoms exactly as Simon suggested ... he definitely doesn't mean it to be literal.

    Atoms don't occupy probability clouds ... that's what the electrons do. Carrol is a bit overly literal when he talks about electrons spinning around the nucleus (as though that picture was literal) but this is an introductory discussion and he certainly knows better.
  8. Aug 14, 2012 #7

    Thanks, I appreciate your help.
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