from a very overdense, non-turbulent core. Their treatment of radiative transfer also showed that a substantial amount of radiation escapes along the polar axis of the structure where it does drive away some material, but it is along the equatorial axis that the accretion occurs. Numerical simulations have now moved on to three dimensions with the work of Krumholz et al. (2005a). The application of adaptive mesh refinement (AMR) hydrodynamical codes (see chapter by Falle) to this problem is finally demonstrating conclusively that radiation pressure is not a barrier to massive star formation. As material rains down on the accretion disc, radiation bubbles repeatedly blow out perpendicular to the disc plane and then collapse down again, but overall the accretion continues. They also find accretion rates of order $\sim$10$^{-3}$  and it would appear that a consensus may be emerging over these kind of rates.

The effects of magnetic fields are the next major ingredient that need to be added to these simulations as computer power increases. It is possible that magnetic flows set in very early on in the accretion process as in the simulations of Tomisaka (2002) for the collapse of magnetised, rotating cores. It is unlikely that the 