physics
The entropy of a system is a measure of that system's disorder. Why is it appropriate to describe a laser as an entropy-reducing device?
I take some issue with the first sentence. It is better, in my view, to describe entropy as a measure of chaos. As chaos in a system increases, the entropy is a measure of that. If the chaos decreases, entropy decreases. Now in a laser, what is happening to the molecules in the laser as it lases? Is it becoming more chaotic, or not?
Reply
Answers
In a laser, the chaos and entropy of the system is actually decreasing. As the laser is "lasing", it is creating coherent light, which is photons of light with precisely the same wavelength and phase. This means that the light emitted from a laser is much more orderly and structured than the chaotic and disordered set of particles that are initially entering the laser. As the system becomes more organized, its entropy is actually decreasing.
