The Lyman alpha (Lya) emission line of atomic hydrogen represents an important feature in the spectra of star forming galaxies, which has been used to find galaxies out to the highest redshifts. Because Lya corresponds to a resonant transition of atomic hydrogen, Lya photons typically undergo a complex scattering process before being observed. The challenge remains to model this resonance-line radiative transfer well enough to infer any properties of the galaxies themselves, and/or of their surrounding intergalactic medium. I will summarize our current understanding of the Lya scattering process, as inferred from existing observations. I will then discuss our attempts to model several aspects of Lya line transfer. This discussion will help me illustrate the main challenges to current models, and how these can be overcome with the expected unprecedented increase in data on Lya emitting sources in the coming few years.
Followed by wine and cheese in Pupin 1402.