"The First Billion Years of the Universe" by Marcelo Alvarez
February 14, 2011 - 10:00am
Our earliest image of the universe - the cosmic microwave background - shows that hundreds of thousands of years after the big bang, it was a relatively simple place. At that time, there were no planets, stars, or galaxies. Space was permeated by an expanding, nearly homogeneous mixture of dark matter and mostly hydrogen gas, devoid of the heavier elements common in daily life. How then did the complex structure we see today develop? I will focus on a key aspect of this problem, namely the story of the very first stars, galaxies, and black holes - how they formed, and how they influenced the subsequent evolution of cosmic structure. In particular, I will show results from numerical simulations that detail how the first stars and black holes illuminated their surroundings with ultraviolet and X-ray radiation, completely reionizing the universe by only a billion years after the big bang. These large scale, massively parallel computations allow us to obtain unique theoretical insights into an epoch of the distant universe which is only just now coming into view of the most powerful telescopes on earth and in space.