This is just an intuitive question, sparked by studying my courses. I haven't got the time to elaborate or search much myself at the moment, my apologies for this.(adsbygoogle = window.adsbygoogle || []).push({});

I was wondering if there was a relation between quantum probability and entropy. Naive formulation of entropy is that a system will tend to its most probable state. This is the state lowest in energy.

When a molecule gets excited to a higher energy level, this law continues to hold generally. Hence, the excited state soon falls back to its ground state, and emitting radiation when doing this.

However, sometimes this process is forbidden by quantum selection rules. When this happens, the excited molecule resists deactivation by radiation. Lifetimes of excited molecules then can become as long as several hours.

So, at least for a short while, the naive formulation of entropy seems to be challenged.

There does seem to be a limit for this: see for instance the Treanor effect, which gives a similar mad pumping of energy to the highest excited state, until a certain level, after which relaxation occurs.

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

Join Physics Forums Today!

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

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

# Quantum probability versus entropy

Loading...

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