One of the most important figures in quantum mechanics was the German physicist Max Planck. After he won the Nobel Prize for physics in 1918, he undertook a lecture tour of Germany.
“Naturally enough the lectures he delivered to the various audiences were more or less identical, a fact that was noticed in due course by his chauffeur.
One day the driver said to him: “Professor Planck, I’ve heard you give the same lecture on quantum mechanics so many times that I now know it by heart. It must be very boring for you, so for tonight why don’t we swap roles? I’ll deliver the lecture and you sit in the audience and wear my chauffeur’s cap.”
Planck agreed and that evening the driver got up on stage and delivered the lecture flawlessly. Then a member of the audience stood up and asked an incomprehensible question about quantum mechanics. Without hesitation the chauffeur said: “I’m surprised that someone from the renowned city of Munich could ask such a basic question. I will leave my chauffeur to answer it.”