This book captures the latest exciting developments concerning one of the unsolved mysteries about our origins: how did the first stars and galaxies light up in an expanding Universe that was on its way to becoming dark and lifeless? I summarize the fundamental principles and scientific ideas that are being used to address this question from the perspective of my own work over the past two decades.
Most research on this question has been theoretical so far. But the next few years will bring about a new generation of large telescopes with unprecedented sensitivity that promise to supply a flood of data about the infant Universe during its first billion years after the Big Bang. Among the new observatories are the James Webb Space Telescope (JWST)—the successor to the Hubble Space Telescope—and three extremely large telescopes on the ground (ranging from 24 to 42 meters in diameter), as well as several new arrays of dipole antennae operating at low radio frequencies. The fresh data on the first galaxies and the diffuse gas in between them will test existing theoretical ideas about the formation and radiative effects of the first galaxies, and might even reveal new physics that has not yet