How to Measure the Expansion Rate of the Universe Without Knowing Its Age
The universe is expanding, and galaxies are flying apart like raisins in rising dough. The rate of this expansion, the Hubble constant, is a key number in cosmology.
Two Flavors of Early Dark Energy Ease Cosmic Tension
Cosmologists faced a recipe problem: the universe's expansion rate measured nearby didn't match the rate deduced from the Big Bang's afterglow — the cosmic microwave background.
Symphony of Nucleosynthesis: How a Sudden Tempo Saved Deuterium
Through three minutes after the Big Bang, the Universe played its first symphony. It was the big bang nucleosynthesis — the formation of light nuclei, where each element sounded its own note, and the tempo was set by the expansion of space.
The Dim Glow of Black Holes Won't Save the Universe
Cosmologists are facing a curious situation: two reliable tools draw slightly different maps of the same universe. One tool is the map of ancient light (the cosmic microwave background), and the other is the map of galaxy distribution. They broadly agree, but in details they diverge.