Re: backward ray tracing

In article <13rsnc2fcocme25@xxxxxxxxxxxxxxxxxx>,
Skywise <into@xxxxxxxxxxxxxxxxxxxx> wrote:

Except that linear gain (e.g., laser gain) has to be turned into linear
loss, and v.v., on time reversal -- which can make for some interesting
and even controversial discussions when one or both are present.

Entropy?


Hadn't thought of that . . .
.