system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: Why is candle wax transparent when it’s hot and opaque when it’s cool?
gpt
When wax is cool, it's crystallized.  These wax crystals can scatter light so it doesn't reach your eyes, so the crystals are opaque.  When hot, the wax molecules are all loose and free, and can't scatter light.  That means the light goes straight through, making the liquid wax look transparent.