Robert Brandenberger

Ordinary matter, described by the Standard Model, is stars, planets, light. But it makes up only a tiny fraction of the cosmos. The rest is dark matter, born after the Big Bang. What's it made of? Possibly ultralight particles. New work shows how two types of such particles can amplify ordinary light.

The universe is a vast, dark ocean. We see only the glowing foam on its surface — stars and galaxies. But hidden in the depths are two invisible forces: dark matter, which with its gravity keeps galaxies from flying apart, and dark energy, which, on the contrary, pushes space itself apart, making the universe expand faster and faster.