Right after the heart stops, the lack of oxygen in the blood shuts the brain down, and the cells of the human body begin to change. The blood stops circulating, and within 20 to 40 seconds of clinical death, all measurable brain activity stops. But that only describes the door swinging shut. What comes next is perhaps life's most enduring mystery. The Greeks believe the afterlife to be the place of neutrality filled with neither sorrow nor happiness, just an empty void where souls journey after their physical bodies have expired. Ancient Mesopotamians believed the afterlife for everyone was a dark and hopeless netherworld where the dead eat dirt and clay. A far cry from visions of harps and wings. The ancient Egyptians saw the afterlife as a place where bad people were swallowed by a crocodile-like creature, called the devourer of souls. And the good people were led to happy fields. Pharaohs built themselves lavish homes full of treasures to comfort themselves in the next life. Though, as far as we can tell, it has stayed here with us. Fifteenth-century painter, Hieronymus Bosch, depicted the heavenly realm as a Dr. Seuss-like garden where unicorns and dragons drank side by side. The obsession with the afterlife continues now even in an age of Facebook and iPads. And our ideas of what happens after we die are no less varied. Contemporary wiccans believe an alien from Venus watches over heaven as it floats five miles above the Gobi Desert. Existentialists believe nothing comes after death. The door swings shut, and we simply cease to be, creating what is known as the existential dilemma. Christians regard heaven as a perfect utopia where those who believe Jesus died for their sins will live forever with God, while hell is eternal separation from God and all that is good. This search for an afterlife seems embedded deep within the human heart transcending all civilizations, generations, and geography. Perhaps this inconsolable longing is itself evidence of heaven as the true home of humanity.