Most of what we know about the universe actually comes from what we can’t see. Only a tiny fraction of the cosmos is made of “normal” matter—the stuff that makes up stars, planets, and us. The rest is a mysterious combination we call dark matter and dark energy, which, although invisible to our telescopes, is absolutely crucial for how the universe expands and how structures form over billions of years. So how do we even study something we cannot see? One of the most powerful tools we have ...