Ehrenfest Theorem: Enunciate & Implications for Classical/Quantum Mechanics

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
2 replies · 2K views
mjda
Messages
13
Reaction score
0
This may seem rather silly, but how would I go about enunciating Ehrenfest’s theorem?

Also, does anyone know what this theorem implies for the relation between classical and quantum mechanics?

Any suggestions or help is greatly appreciated!
 
Physics news on Phys.org
mjda said:
This may seem rather silly, but how would I go about enunciating Ehrenfest’s theorem?

Also, does anyone know what this theorem implies for the relation between classical and quantum mechanics?

Any suggestions or help is greatly appreciated!

It's pronounced pretty much as it's spelled, but The first E is a short e as in bed, and the h is silent.

What Ehrenfest's theorem says about the relationship between classical and quantum physics, is that the expectation values (average values) of quantum observables evolve according to Newton's laws:

The time derivative of the average momentum is equal to the average force
The average momentum is equal to the mass times the rate of change of the average position.