Large galaxy clusters contain both dark and normal matter. The immense gravity of all this material warps the space around the cluster, causing the light from objects located behind the cluster to be distorted and magnified. This phenomenon is called gravitational lensing. NASA/ESA
Nearly a century after dark matter was first proposed to explain the motion of galaxy clusters, physicists still have no idea what it s made of.
Researchers around the world have built dozens of detectors in hopes of discovering dark matter. As a graduate student, I helped design and operate one of these detectors, aptly named HAYSTAC (Haloscope At Yale Sensitive To Axion CDM). But despite decades of experimental effort, scientists have yet to identify the dark matter particle.