Nikolay Sergeevich Krylov (10 August 1917 – 21 June 1947) was a Russian theoretical physicist known for his work on the foundations of statistical physics. He showed that a sufficient condition for a dynamical system to relax to equilibrium is for it to be mixing.
Krylov was born in Ustyuzhna (now in Vologda Oblast of Russia). He graduated from Leningrad University with a degree in physics. He then studied with Fock and wrote a thesis on the foundations of statistical mechanics titled Mixing processes in phase space.
Krylov died after a prolonged illness.