The First Sources of Light in the Universe

The formation of the first stars and quasars marks the transition between the smooth initial state and the clumpy current state of the Universe. In popular CDM cosmologies, the first sources of light started to form at a redshift z=30 and ionized most of the hydrogen in the Universe by z=8. Current observations are at the threshold of probing the reionization epoch. The study of high-redshift sources is likely to attract major attention in observational and theoretical cosmology over the next decade.