[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!

[Bjartr]

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.

[lukan]

Indeed. There is only an absolute zero, that cannot get colder, but more heat is always possible as more heat means more rapid movement of elements. While absolute zero at 0 K means no movement.

[lukan]

Are you aware of that old concept and why it doesn't work?

https://de.wikipedia.org/wiki/Perpetuum_mobile

Same principle.

Basically, what you propose negates the nature of reality. There is always friction/energy loss into heat (increased chaotic movement). Only way to deal with it, if you want permanent cycles, is constantly add energy in the same amount that is lost.