How Do Scientists Know How Old Dinosaurs Really Are?

Daniel has been watching a dinosaur documentary. The narrator says a fossil is sixty-five million years old. He never stopped to wonder how anyone actually knows that. The fossil does not come with a date on it. And scientists usually do not date the fossil itself -- they date the rock around it. This episode explains how, starting with one of the most elegant ideas in all of science: that certain atoms decay at such a perfectly predictable rate that they function as natural clocks, running continuously since before anyone was there to read them. What you will find in this episode: What radioactive decay actually is -- and why it happens at a fixed, predictable rate What a half-life is and how measuring it gives you a date Why carbon-14 dating does not work for dinosaurs -- and what does instead How volcanic rock layers bracket a fossil's age from above and below Why scientists cross-check multiple dating methods against each other The closing line about what every rock actually is Short, precise, and the kind of episode that changes how you look at every fossil you have ever seen. Listen, wonder, and learn. Find us @smilewithDaniel everywhere.