Intense, brief flashes of radio light called fast radio bursts (FRBs) travel across billions of light-years to reach Earth, passing through a fog of matter along the way. The bursts’ origins are unclear but may originate from highly magnetized dead stars called magnetars. The denser the fog through which FRBs travel, the more dispersed their signals become—similar to the way a prism splits white light into a rainbow of colors.

Thanks to this dispersive property, FRBs make excellent tracers of how ordinary matter is distributed in the universe; ordinary matter is the same stuff that makes up people, planets, stars and anything made of subatomic particles called baryons. As the FRB radio beams pass through this matter in our universe, they can essentially map out how much is present and how clumpy it is.

In a new Nature Astronomy study, researchers show how these FRB measurements can help solve some of the biggest questions in cosmology.