system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does paper become translucent when oil is rubbed on it?
gpt
The light scatters when it goes between air and not-air. Since paper is made of fibers, light hitting it goes between air and not-air a lot. When the paper is soaked in oil, the light only goes from air to not-air once, and so is scattered much less.