I am considering going to Columbia for graduate school to study condensed matter physics. According to USNEWS they're fairly highly ranked (#12 in condensed matter), but their website only lists 9 condensed matter faculty members. Considering that many other universities with similar rankings have upwards of around 15 faculty members, Does anyone know how this can be the case? Is this just another instance of rankings being a hollow metric, or is it maybe that Columbia's group is particularly productive despite it's small size? This is mostly just a curiosity for me, regardless of the answer there's some interesting research going on.