And that's a very, very, very big deal.

To learn about Kirchhoff's law and exactly why it's invalid, see these lectures:

> What is Kirchhoff's Law? Blackbody and Cavity Radiation!
https://youtu.be/DodFojdkSIA

> Is Kirchhoff's Law True? The Experiment!
https://youtu.be/YQnTPRDT03U

> Kirchhoff's Law - The Second Experiment!
https://youtu.be/LE7fZ565DWc

> Kirchhoff's Law, Max Planck, and the Carbon Particle!
https://youtu.be/m-poyIY7pfQ

> Kirchhoff's Law vs the 2nd Law: The "Boxes Side-by-Side Experiment"!
https://youtu.be/rsQXu5qLkgg

> Kirchhoff's Law vs the 0th, 1st, and 2nd Laws: The "Box in a Box" Experiment!
https://youtu.be/5cS1mfZ2XYY

> Linking Planck's Equation with the Physical World!
https://youtu.be/_w8PJZvnLGI

> The Big Bang, Photons, & The Microwave Background!
https://youtu.be/NHOo3elX5-c

> History of Kirchhoff's Law - Presentation at The German Physical Society
https://youtu.be/83JU6enMBS0

BTW this is all about Kirchhoff's thermal law, not his circuit laws.