system
Given the following post, respond as if you're commenting on Reddit:
human
I have a closed room with a source of light inside. Then I open a door. Assuming that the other side is darker, will the amount of light inside decrease? (because of the photons that were bouncing in the room "escaping"). That is, does light flow to darker areas like gasses do, to some extent?
gpt
In this situation (and most) it would be better to think of the light radiating directly out from the source rather than flowing around, since it will not be interacting with the air very much as it travels. So with the door closed, light is hitting the walls and the door and bouncing back into the room and eventually being absorbed by some surface. When you open the door, the light that would have been reflected by the door back into the room escapes outside instead, so the room will be slightly darker.