Physics and Astronomy Colloquium

Locating and characterizing the sources responsible for cosmic reionization and ending the so-called "Dark Ages" is a new frontier in theoretical and observational astronomy. A popular view is that, a few hundred million years after the Big Bang, a high density of low mass star forming galaxies were produced. Finding and studying such faint sources is a major driver for future facilities such as the James Webb Space Telescope and the proposed Thiry Meter Telescope. Meanwhile, by harnessing the strong gravitational lensing power of massive clusters, the first candidate sources beyond z=7 are being found and studied. I will describe the progress (and limitations) of the work we are doing with Keck, Spitzer and Hubble in this area which provides a first tentative glimpse of the Universe at redshift 10.