Kirchhoff's law for black body radiation is wrong as it has a term that has a limit of zero making his equation for black body radiation undefined mathematically in the case of perfect reflectors.
Plank used kirchhoff's law and continued to use it in violation of thermodynamics
This has fucked up our cosmology as a result. Apologize all you fucks that think Kirchhoff was every right and not just someone that cut corners and incorrectly reworded the work of others to financially support himself but never confirmed anything by experimentation.