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B Question about entropy, particles

  1. May 29, 2017 #1
    Hello, I am a curious layman, so I might have some misconceptions. I have been pondering some questions, and I was hoping someone might be able to either confirm, or explain this. What I am wondering, if I am understanding this correctly, is why atoms do not experience entropy? If this is true, why? The next thing I was wondering, is about the effect of observation on a particle. Is the particle and wave coexisting in two different dimensions as a wave and a particle, then when observed,is the particle and wave "switching" with each other? Regardless of the answer to the last question, is there an energetic change happening during the collapsing of the wave function happening upon observation? I thank you very much in advance for your time and thought.
  2. jcsd
  3. May 29, 2017 #2


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    Entropy is a concept that is related to the statistical behavior of a very large number of atoms or molecules. Much like saying that the "average value of a given set of 1000 numbers is 25.714" doesn't really tell anything about any single number in that set, the concept of entropy is not useful when explaining the behavior of a single atom or molecule.

    Quantum objects don't fundamentally change in nature when they are observed. When a position measurement is made for a particle, the standard deviation of the position probability distribution of the particle typically becomes much smaller than it was before the measurement, but it's still same kind of a quantum object.
  4. May 29, 2017 #3
    Thank you! I understand your answer about entropy. About the particle: So you are saying that besides the position of the particle, there is no other fundamental change? Regarding the double slit experiment, I find it fascinating that mind is at least partially interacting with quantum reality, is this actually what is happening, or am I missing something?
  5. May 30, 2017 #4


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    It depends on what you observe. For example, if you observe the position, then it has a well-defined position, but not a well defined momentum. If you measure the momentum, it has a well-defined momentum, but not a well-defined position. Of course, any measurement also has limited resolution. Wave-particle duality is an old-fashioned idea, so you shouldn't worry about what that means.
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