Two University of Miami astrophysicists believe a recent unusual signal detected by a powerful ground-based observatory could provide solid evidence that primordial black holes, thought to have formed in the cosmic soup just after the Big Bang, really do exist. A primordial black hole weighing the mass of Earth would have an event horizon (the point of no return for infalling objects) about as wide as a US dime coin. If the Universe is full of these dime-sized black holes, how can they be detected?