One of those things that folk who do physics "know", but is counterintuitive: light is mostly invisible.
Not just the fact that most of the EM spectrum is invisible...most of the visible (in theory) stuff, red, green, blue and all that, is invisible.
We only detect light when it hits our eyes. I hope that's fairly intuitive. So a lot of light scattering off whatever...in fact almost all of it...never reaches your eye, or any human eye. So it's invisible.
Wait, there's more....
Laser beams - yeah, red ones. They're invisible until they bounce off a wall or something (see also, our puffer thing full of laser beam detection powder...or talc). You can't see laser beams other than the wall/lens or whatever they hit, unless you're in a dangerously contaminated atmosphere...or one full of laser detection powder/smoke.
But wait, there's more....
Or unless you are in a fog (which iiuc might not be dangerously contaminated) or underwater.
