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

I think what you’re getting at is the concept of a “diffuse” reflection.

Then image of your hand is being sent of in every direction, but most surfaces are too rough to meaningfully reflect that image back into your eye. The light falls on nearby walls and surfaces and is randomly scattered to produce a new image of whatever it hit.

You can view this indirect “virtual” image in a mirror, which reflects light back at the same angle it came in at instead of at a random angle.

Because it *doesn’t* scatter much light, you can’t actually look at the mirror itself (the backing is aluminum and the glass is faintly green) very easily – only the reflected image that overwhelms it.