Nova: Particles Unknown

What's the most common?yet most elusive and least understood-particle in the universe? The neutrino. Starting with the invention of the nuclear bomb, billions of dollars have been spent in pursuit of this so-called ghost particle. Outnumbering atoms a billion to one, neutrinos are preposterously plentiful, they hardly interact with anything, and they mystifyingly morph between three different forms. Producer: Laurie Cahalane, Allison Todd, Henry Fraser. Narrator: Eric Meyers. Author: Henry Fraser.