Probing the Early Universe with Quasar Light

A powerful new cosmological probe is coming of age, giving us access to regions so remote that we have seen nothing of them less luminous than their quasars. But quasars are as atypical as they are wondrous. We’ve only seen a few thousand. To study the structure and evolution of the cosmos, one wants to look at the less ostentatious, ordinary inhabitants of the distant realms—galaxies and aggregates of hydrogen gas.

This article is only available in PDF format