system
Given the following post, respond as if you're commenting on Reddit:
human
When metal is hot enough to start emitting light in the visible spectrum, how come it goes from red to white? Why don’t we have green-hot or blue-hot?
gpt
All objects emit black-body radiation. This comes in the form of electro-magnetic radiation. The intensity and spectrum (color) of this radiation depends on the temperature of the object.

At room temperature and below, the radiation is too low frequency to be able to seen by human eye, but objects do glow at infrared, and that is why heat vision cameras work. At about 500 degrees celsius, you can start noticing objects to glow at red. Increasing the temperature further makes them brigther, and whiter. And if you continued to heat the object beyond about 6000 celcius, then the glow would transition from white to blue.

The reason why you wont find green hot objects, is because when the objects spectrum peaks at green, it will also emit a lot of red and blue, and this mixture gives the overall white look.

The reason you wont easily find blue hot metals, is because everything evaporates before that. How ever, some stars are hot enough to glow blue.