Nitrous oxide was supposed to revolutionize surgery. Instead, it threw Victorian scientists into giggling fits and accidentally revealed that emotions, pain, and social connection all share the same neurochemical plumbing — a discovery that explains why heartbreak literally hurts, why laughter is a painkiller, and why your brain processes rejection the same way it processes a broken arm. The history of one laughing gas demonstration in 1799 quietly rewired how we understand every relationship you've ever had.