During a physics lecture, the professor wrote the equation
E = h v
on the board. He then asked “What is v?”
“Good. And what is h?”
“The length of the plank.”
Adapted from Physicists continue to laugh, MIR Publishing, Moscow 1968. Astonishingly, this is translated directly from the Russian version of the joke.
He's right, I checked with a Russian-speaking philologist (who has an astounding resemblance to this philologist).
From MIT's Technology Review:When objects get very close, Planck's law is violated.
Any time you see a piece of metal glowing red-hot, or turning yellow or white as it gets hotter, you're watching Planck's law in action. The century-old principle, which describes how energy is radiated from an idealized nonreflective black object, applies to everything from a cast-iron frying pan to the surface of a star. But it turns out to have a loophole.
Planck's law says that thermal emission of radiation at different wavelengths follows a precise pattern that varies according to the temperature of the object. When the German physicist Max Planck proposed the law, in 1900, he suspected that it wouldn't apply when two objects were very close together. But it took until this year to prove his hunch, because keeping objects that close without letting them touch is a major challenge. Now MIT researchers have shown that heat transfer between objects a few nanometers apart can be three orders of magnitude greater than the law would predict....MORE