Puxun Wu

Fast radio bursts are brilliant cosmic flashes that, like a starting signal, set off a race of radio waves across the universe. Astronomers used them as a natural laboratory to test whether the photon, the quantum of light and the carrier particle of the electromagnetic interaction, has mass.

A distant radio signal travels toward us through gas, and the more gas it encounters, the more the signal is 'slowed down.' Astronomers use this to weigh the invisible envelope of our Galaxy: its halo. But if the halo is uneven, like a thick scarf draped over the shoulders, measurements in different directions will differ.

The Universe is expanding, but at what speed? Astronomers have been arguing for decades about the precise value of the Hubble constant. Two classic methods give slightly different results. Now there's a third — using mysterious radio bursts.

The cosmological kitchen is full of invisible ingredients. Dark matter, like an invisible scaffold, keeps galaxies from flying apart, while dark energy, like yeast in dough, makes space expand ever faster.

In the scorching plasma of the infant Universe, right after inflation, conceived by Alan Guth, the kinetic dominance epoch reigned.