GENEVA (AN) — This Halloween, scientists celebrate a cosmic riddle of mysterious material known as "dark matter" they believe makes up most of the universe and holds it all together. Along with pumpkin-carving and trick-or-treating, it's "Dark Matter Day" around the world.
Scientists, institutions and others gather at local events to talk about one of the hottest pursuits in particle physics: the hunt for dark matter, a theoretical material that does not emit light or energy and cannot be directly observed.
