system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does a room go dark after the light goes out? Where does the light go, and does it take a brief moment for this process to happen, or is it nearly instantaneous the room goes dark after the light goes out?
gpt
Think of it like a hose... and a room made of sponge.

The light bulb is a hose, spraying water (light) everywhere. The room is a sponge, absorbing the water (light) all the time. 

The moment you turn the light off, it's like closing the faucet to which the hose is attached. It stops spraying water (light) everywhere, the sponge absorbs any water still traveling through the room.

The water (light) does not vanish instantaneously. It travels until it hits some sponge which absorbs it. It travels extremely, extremely fast, mind you, but it does take a finite amount of time to vanish.