Trivia: Einstein won the Nobel Prize in physics in 1921 for explaining what?
Photoelectric effect
Spontaneous radiation
Gravitational pull
Supersymmetry
The correct answer is Photoelectric effect
So why is this answer correct? : Though Einstein is most famous for his theory of relativity, the public still wasn’t totally sold on the theory in 1921. That’s why Einstein won his Nobel Prize for explaining the photoelectric effect — though he went ahead and lectured on relativity in his acceptance speech anyway.