A hundred trillion neutrinos from the sun fly through you every second. At any moment, there are three hundred of these subatomic particles in the tip of your pinky alone that are ancient relics from the Big Bang. Neutrinos are key to explaining why the sun shines, and may even be the reason why you and everything else in the universe exists at all. And yet, scientists know surprisingly little about these ghostly particles that surround us and flow through us every moment of our lives. Experiments are on the verge of resolving many neutrino puzzles, but for now they are the most mysterious known particles in the universe. James Riordon, author of Ghost Particle: In Search of the Elusive and Mysterious Neutrino, describes the neutrino’s discovery and the current status of research into this topic.