How are we able to measure the half life of uranium-238 if it’s 4.5 billion years?

Question

Tried looking it up and it got complicated real quick.

In: Physics

Answer 1

You can tell a turtle would take 10 years to circle the world without having to sit there for 10 years and watch it. You just track the progress. Half-life doesn’t mean it doesn’t do anything for a billion year and then half overnight.