system
Given the following post, respond as if you're commenting on Reddit:
human
Why is it when things get hot, they become red?

I mean the extra energy would change the objects state of matter, but how would that change how it reflects light?
gpt
The red is not because it reflects light differently, the red light is coming from the object itself. 

The object is the one giving off the light. 

All objects not at absolute zero give off light. Under normal temperatures, the light is mostly infrared which we can't detect. At higher temperatures, the objects start giving off visible light. 

This is known as blackbody radiation and applies to everything, although objects like metals will approximate closer to it.