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Question about Planck's constant

  1. Nov 15, 2005 #1
    I was talking to my friend (who's a physics major) about the difference between quantum and classic mechanics. Planck's constant came up somehow and my friend said that you could use it to determine with a system can be described by classical or quantum mechanics. I thought he was crazy since it's just a constant, how can it determine anything? That's like saying the speed of light can determine how fast a system is moving... it doesn't make sense. Anyone have any comments? Is he right or making everything up?
  2. jcsd
  3. Nov 16, 2005 #2
    Methinks your friend meant that quantum mechanical models are for atomic phenomena & are to be applied when the action is of the order of Planck's constant. Regards,
  4. Nov 16, 2005 #3


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    Even that can't explain it since planck scale is many OOM from the atomic scale. It seems too ambiguous to determine what the OP meant...
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