The clumps of matter in this baby picture of the universe evolved into the galaxy superclusters we see today, and it was dark matter that clumped first and drew the regular matter together. The amount of bending can reveal the amount of dark matter. And while no one knows what all the dark matter is, scientists have discovered that some small fraction of it is made of neutrinos — tiny, fast-moving particles that don’t really interact with normal matter. So far, they haven’t managed to capture a dark matter particle in action. But researchers are taking dark matter — whatever it is — into account when they think about how the universe evolves.