system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can humans see fire? What is the light we’re actually seeing?
gpt
When things are very hot they glow red. The soot and ash in the fire - mostly particles too small to see - are super hot and glowing red. You see this glow. If even hotter they can glow blue. Some materials may add color.