Probabilistic violation of entropy by radiation

by Hypatio
Tags: entropy, probabilistic, radiation, violation
Hypatio is offline
Apr15-12, 01:56 PM
P: 85
Consider a solid body at some constant temperature. Heat is transported by conduction and radiation. The radiative component transports heat by the d-d electronic transitions which emit photons and they are absorbed by molecules somewhere else in the body. I presume that the direction of emission is quantum mechanically indeterministic.

It seems that entropy will only hold by a law of large numbers and thus entropy is regularly violated on small scales with the probability of a certain magnitude of entropy violation decreasing with the size of the system.

In other words, while very improbable, it could occur that in our body of constant temperature, a large number of photons could be emitted on one side of the body which is absorbed by the other side of the body. This would mean that heat can be radiatively transported from regions of low temperature to regions of high temperature. Although improbable for large bodies, it would also seem that this would be a regular occurrence over small scales and timescales.

Phys.Org News Partner Physics news on
Physicists design quantum switches which can be activated by single photons
'Dressed' laser aimed at clouds may be key to inducing rain, lightning
Higher-order nonlinear optical processes observed using the SACLA X-ray free-electron laser
mathman is offline
Apr15-12, 04:09 PM
Sci Advisor
P: 5,937
You have observed that the rule that entropy always increases is statistical.
Mute is offline
Apr15-12, 04:19 PM
HW Helper
P: 1,391
See the fluctuation theorem wikipedia article for the mathematical statement of the probabilistic nature of entropy.

Register to reply

Related Discussions
Hawking radiation, BH entropy and so on in Kottler spacetime Special & General Relativity 0
blackbody radiation entropy Introductory Physics Homework 1
Black body radiation entropy question Advanced Physics Homework 4
Entropy of blackbody radiation Classical Physics 4
Probabilistic complexity classes and acceptable sources of entropy Set Theory, Logic, Probability, Statistics 0