Since it's true in quantum mechanics that expectation values obey the classical equations of motion, then if you have a whole bunch of particles, would most of them behave classically?(adsbygoogle = window.adsbygoogle || []).push({});

I thought to get classical mechanics you needed big particles, but Ehrenfest's theorem says lots of small particles would do.

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Ehrenfest Theorem

**Physics Forums | Science Articles, Homework Help, Discussion**