The Origin of the Initial Mass Function
Mark Krumholz

Star-forming environments vary by orders of magnitude in density, pressure, metallicity, and other properties, yet the initial mass function (IMF) of the stars they produce remains stubbornly unchanged. Explaining the origin and universality of the IMF is one of the oldest problems in theoretical astrophysics, but in the last few years advances in understanding how gas fragments, together with algorithmic improvements that have allowed simulations to include physics such as radiative transfer, have produced significant progress. I describe these advances, and lay out the beginnings of a theoretical model capable of explaining the IMF.