Dark Matter in the Universe

The nature of the dark matter in the Universe is among the longest and most important outstanding problems in all of modern physics. The ordinary atoms that make up the known universe, from our bodies and the air we breathe to the planets and stars, constitute only 5% of all matter and energy in the cosmos. The remaining 95% is made up of a recipe of 25% dark matter and 70% dark energy, both nonluminous components whose nature remains a mystery. I’ll begin by discussing the evidence that dark matter is the bulk of the mass in the Universe, and then turn to the hunt to understand its nature. Leading candidates are fundamental particles including Weakly Interacting Massive Particles (WIMPs), axions, sterile neutrinos, light dark matter, as well as primordial black holes. I will discuss multiple experimental searches: at CERN in Geneva; in underground laboratories; with space telescopes; with gravitational wave detectors; and with ancient rocks. I’ll tell you about our novel idea of Dark Stars, early stars powered by dark matter heating, and the possibility that the James Webb Space Telescope has already discovered them. At the end of the talk, I'll turn to dark energy and its effect on the future of the Universe.