This illustration shows the distribution of dark matter, massive halos, and luminous quasars in a simulation of the early universe, shown 1.6 billion years after the Big Bang. Gray filaments show the distribution of dark matter. Small white circles mark concentrated "halos" of dark matter. Larger blue circles mark the most massive halos, which host the most luminous quasars.
Paul Bode/Yue Shen, Princeton University