Soviet Nobel laureate Lev Landau kept a list of names of physicists which he ranked on a logarithmic scale of productivity ranging from 1 to 5. Albert Einstein was ranked 0.5. Landau awarded a rank of 1 to Bose along with the founding fathers of quantum mechanics, Niels Bohr, Werner Heisenberg, Paul Dirac and Erwin Schrödinger, and others. Landau ranked himself as a 2.5 but later promoted to a 2.