YAY my physics (light and heat) final is over. If you don’t understand the physics problem in this comic, it’s about the critical angle of refraction between two substances. Basically the idea is that light bends when it transitions from moving through air to moving through water, and there’s some angle at which it bends enough that it doesn’t actually reach your eye. When that happens, you can only see the ftarrh.
You can try this with a coin and a glass of water. Set the glass on top of the coin, and you should be able to see the coin through the side of the glass. Then fill the glass with water, and suddenly the coin vanishes. woooo science