Eli5: why are the light waves bouncing off an object, allowing us to see what and where it is, only seen “directly” but aren’t seen going in every direction away from the object?

Question

Tough question to articulate, but hopefully very answerable.

Presumably, from whatever angle imaginable away from your hand, as an example, there is information in the form of [light waves?] about the shape and color of your hand, but that information only becomes relevant from your unique perspective. “Directly” let’s say. You can’t see the “data”/lightwaves being sent in every other possible direction away from the hand, even though no matter where you are in the room, assuming nothing obscures your view, you could see the hand.

In: Physics

Answer 1

To give some extra context, imagine laser pointers.

Normally you can only see the spot on whatever surface you shine it on, and MAYBE a small bit of the beam as it hits bits of dust or something floating around. For the most part, because they are such direct beams of light, there is no light to enter your eyes.

Now, imagine you shine it through fog or smoke. That puts a lot more into the air for it to bounce off of, just like in those scenes in heist or spy movies, where they spray stuff to make laser grids visible.

Now, once you get strong enough lasers, or maybe lasers of a specific type, I’m not sure of the specifics, then you start to have beams that are just always visible. A lot of these are gonna be like those high powered burning lasers you see on things like Styropyro videos. They put out enough power that just looking at the spot on the wall, much less getting hit with the actual beam can cause permanent eye damage.