Symmetry factor

Lev Davidovich Landau, a brilliant theoretical physicist and a founder of a whole school of thought in theoretical physics, was born exactly one hundred years ago, on 22 January 1908. His work was amazingly broad, from condensed matter physics to quantum field theory. He is also an author of a renowned course in theoretical physics. He was awarded the Nobel Prize in 1962 for his work on superfluidity of liquid helium. He is one of the few people in the world whose student also got a Nobel Prize…

It is interesting that he instituted a practice of a “Landau minimum” for prospective theorists in many theory departments in USSR – any student who wanted to work with a theory group would have to pass a special exam. This exam was an N-part (and N-day) affair, with N<10 being a number of subjects (Classical Mechanics, Electrodynamics, Quantum Mechanics, ….) that a particular theory department wanted that student to pass. 10 here is the number of volumes in the famous Landau-Lifshts course of theoretical physics mentioned above. For the memoirs of his wife about Landau’s life, see here (in Russian).