You probably watched the fireworks. Two hundred and fifty years of the American experiment deserves fireworks, and for a few hours over the holiday weekend the sky looked the way it is supposed to look. But you saw the other pictures too, because everyone did. Roughly four hundred men in khakis and white masks marched through Washington to a drumbeat on the nation’s birthday, carrying flags most Americans thought belonged to museums. The next morning in Memphis, National Guard troops on domestic deployment killed a man in the early hours. And in the days before the holiday, the fight over voting rules froze the House of Representatives so completely that the Speaker gave up and sent everyone home early.

If you are like most people I hear from, you carry a question now that you don’t say out loud at dinner, because saying it feels like betraying something. The question is: how does this end?

I want to introduce you to a man who answered that question in writing, in one of the world’s most respected scientific journals, sixteen years ago. Not with opinion. With mathematics. And I want you to hear both halves of his answer, because the second half is the reason I’m writing this at all.

Peter Turchin was born in 1957 in a closed Soviet science city, the son of a dissident computer scientist. He was twenty years old and studying biology at Moscow State University when the government exiled his family from the Soviet Union for his father’s activism. He rebuilt his life in America, took a doctorate in zoology, and spent two decades doing something that had nothing to do with politics: building mathematical models of animal populations. Beetle outbreaks. Lemming crashes. The booms and busts of living systems, captured in equations that actually worked.