Ehrenfest's Theorem

  • Thread starter yukcream
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  • #1
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Can anyone tell me what is the Ehrenfest's Theorm in quantum mechanic, I don't understand how it can provide an example for correspondence principle?
 

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  • #2
Galileo
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Are you familiar with the equation of motion:

[tex]\frac{d}{dt}\langle Q \rangle = \frac{i}{\hbar}\langle [H,Q] \rangle + \langle \frac{\partial Q}{\partial t}\rangle[/tex]

where Q is an observable?
Try putting Q=p (momentum) and Q=r (position).
 
  • #3
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Now I am a bit confused. What's the name of that theorem which forbids static electric and magnetic charges to produce stable equillibrium condition in 3D ?
 
  • #4
robphy
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DaTario said:
Now I am a bit confused. What's the name of that theorem which forbids static electric and magnetic charges to produce stable equillibrium condition in 3D ?
Are you looking for Earnshaw's Theorem?
 
  • #5
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hehehehe....thank you a lot... I am getting old, my son...
 
  • #6
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Galileo said:
Are you familiar with the equation of motion:

[tex]\frac{d}{dt}\langle Q \rangle = \frac{i}{\hbar}\langle [H,Q] \rangle + \langle \frac{\partial Q}{\partial t}\rangle[/tex]

where Q is an observable?
Try putting Q=p (momentum) and Q=r (position).

It is just the result of the theorem! Any mathematical divide inside?
 
  • #7
Gokul43201
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Yes, the mathematics of showing the correspondence principle at work comes from doing what Galileo suggested and arriving at the classical equations of motion.
 

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