In 1950, physicist Enrico Fermi famously asked, "Where is everybody?" He wasn’t asking because of an eye problem; he was puzzled by why we haven’t seen any signs of extraterrestrial life. If life is common in the Universe, then we should be seeing signs of it. Over the last 60 years, scientists have come up with various explanations for this mystery, which is now known as the Fermi Paradox.