Comment by 9d
I understand, but what I mean is, what if there is no more opportunity for the light to emit heat, because the surrounding environment is already saturated with so much heat that it can't accept more? Is this a possible way to prevent the light from emitting heat and therefore prevent the light from decreasing its luminousness? There must be a way!
Why must there be a way?
A few notes: * There's no such thing as "absolute hot" state that meansno more heat can be added * Blackbody radiation means that above a certain temperature, regardless of what you make your mirror out of, it will be spontaneously emitting visible light at all times.