Pain is a subjective experience; there’s no real way to scientifically measure how much pain a person is in. But scientists are making some progress in locating and measuring pain in the brain. This is a particularly important field of study for the millions of people who experience chronic pain—where pain is no longer a symptom, but the disease itself. Learn all about how scientists are studying pain and what the future holds for the subject in this article from the New Yorker: