Why does my green laser pointer (532 nm) turn yellow when it touches the orange part? It will not change the color on any other surface. Due to the fluorescence of the surface material/pigment/paint. Usually we can observe it with ultraviolet light or at least a blue light source. But F. means consuming certain wavelengths of light and producing longer light.
My green laser pointer (I think we all use near wavelengths) also does the same thing on some light-colored surfaces: toys, decorations, etc. (fruit-shaped refrigerator magnets). Modern pigments were developed to be as bright as possible, so not only the shortest part of the spectrum can be obtained, but also a long wave can be obtained.
Is the green laser more dangerous than the red laser? Finally, the lens in your eye cannot correct for chromatic aberrations. Your brain filters out color fringes most of the time, so it feels as if they don’t exist. One side effect is that your eyes focus green light better than red light, so the focus intensity of laser pointer is higher than red and it is more harmful.
If we place a laser beam between two mirrors, it will continue to reflect between them. Will it last forever? The mirror never reflects all light. Some will be absorbed and turned into heat, even with the best astronomical mirrors. After enough reflection, the light will disappear completely.
Launching the laser into open space is a better choice. It will slowly spread and get lost in the starlight, but it is unlikely to really stop for a long time. I think this is a thought experiment, the laser transmitter can be opened in time, plus the usual warnings about vacuum, no external force, spherical cows, etc.