Question about light

[RecoveringYuppy]

@Vorpal,

That's true. And still not the complete story though.

 

[Delvo]

It's usually blue because it absorbs red/orange/yellow/etc. and reflects blue---that's why blue paint, or blue fabric, etc., appear blue. As usual, though, there are complications.

How about blue-colored glass? Rather than reflecting blue light, a blue filter might absorb everything except blue, and transmit blue. Or it might reflect some blue, transmit some blue, and absorb everything else. You can make glasses that do several different things--- for example, it might transmit red, reflect blue, and absorb everything else---these are called "dichroic". This sort of glass will look red if there's a light source behind it, but look blue if there's a light source in front of it.

Ya, all of these posts that have talked about light getting reflected or absorbed miss at least one other major possibility: just passing through. When I fought forest fires, I noticed that, while black or gray smoke just affected the brightness below, not the colors, walking under a blue smoke plume meant walking into a world of red and yellow; blue smoke casts red shadows. (The smoke plumes come in somewhat different colors according to what kind of fuel they're burning, so you can tell what type of ecosystem the fire has gotten into from miles away.) Blue was what bounced off of the smoke, and red was what went right through like the smoke wasn't there.

(Part of the reason I remember it was because of the physics lesson in it, about how it was different from red or blue stained glass.)

It's funny that people forget about light possibly just going right through stuff, because it's kindo important to us; if light didn't pass through air so easily there'd be no point in having vision at all!