The Reionization of the Universe by the First Stars and Quasars
  The first light from stars and quasars ended the ``dark ages'' of the universe and led to the reionization of hydrogen by redshift 7. Current observations are at the threshold of probing this epoch. The study of high-redshift sources is likely to attract major attention in observational and theoretical cosmology over the next decade. 
Abraham Loeb (Harvard University) and Rennan Barkana (IAS, Princeton   NJ)