"Limits exist everywhere in nature. Physics, chemistry, biology, geology, astronomy—pick your field, dig into the literature, and you’ll soon be struck by how everything in the universe is defined by limits of temperature, weight, volume, density, number, power, frequency, speed, and more. Limits enable the functioning of systems at scales from the subatomic realm all the way up to galaxy clusters. If there is any physical thing that could credibly be claimed to be infinite, it is the universe itself. But not all cosmologists believe the universe is infinite, and proving whether it is or not may be impossible in principle. Leaving the totality of the cosmos to one side (an action possible only within the human brain—which does, most assuredly, have its own limits), everything else we encounter in life has boundaries. So, why have many people become obsessed with either denying or overcoming limits, to the point where they appear to feel that life can have meaning only if it’s tied to some limitless thing, quality, or substance? Humanity’s obsession with limitlessness probably began with the origin of language, which enables the asking of questions. People tens of thousands of years ago began to ask, “What happens to our essential sense of self when we die?” Their efforts to manage existential terror likely led them to tell stories about a boundless otherworld in which the dead live forever. Looking up at the night sky, they saw a realm of blackness punctuated by moving points of light; upon this screen they projected their wants, needs, and fears. Our lives and those of all the creatures around us may be brief, these early people must have thought, but there is another dimension that lies beyond—a dimension without endings. We’ve been searching for a path to infinity ever since."