nLab black body radiation

Idea

What is called black body radiation is the electromagnetic radiation emitted by an ideal non-reflecting (“black”) piece of matter in thermal equilibrium with the electromagnetic field around it, at any given temperature.

The experimentally observed black body radiation spectrum is a key effect and property of quantum physics, governed by energy/frequency quantization controlled by Planck's constant. In contrast, in classical field theory black body radiation comes out incorrectly, with an infinite energy] in the high [[frequency? modes (historically: “ultraviolet catastrophe”).

References

• Wikipedia, Black body radiation