the.com/thermal radiation
everything above absolute zero is snitching on its own temperature, constantly, via light.
means the electromagnetic radiation any object emits simply because it has heat, with the wavelength and intensity determined by its temperature.
from formalized in the late 1800s when physicists tried to explain why hot objects glow — the puzzle of blackbody radiation, which stumped classical physics until planck quantized energy in 1900 and accidentally invented quantum mechanics.
you glowhumans emit infrared radiation constantly, invisibly, at 98.6°f
color equals tempred stars are cooler, blue stars are hotter
broke physics oncethe ultraviolet catastrophe forced planck to invent quanta
needs no mediumit crosses the vacuum of space just fine