Lagos, Nigeria. 3:47 AM The monitor said the patient was stable. Heart rate: 72. Blood pressure: 120/80. Oxygen saturation: 98%. Every number was green. Every number was perfect. At 3:52 AM, the patient's heart stopped. The monitor didn't know. The sensor had failed at 3:46 AM. It stopped sending data. But the monitor didn't know how to say "I don't know." So it said "72 beats per minute." It said "Everything is fine." It said "Nothing to see here." The nurse checked again at 4:15 AM. Still 72. She wrote "Patient stable" in the chart. At 4:30 AM, the patient's daughter arrived and knew something was wrong. But it was too late. The monitor had been lying for forty-four minutes. Every Engineer Should Be Terrified Of This Sentence "It works." The most dangerous sentence in engineering. When you say "it works," you mean: "In the scenarios I imagined, with the inputs I tested, the system behaved a...