If you drink two cups of coffee at 8 a.m., how much caffeine will be left in your body that night at 8 p.m.? Certainly after 12 hours it can’t be that much, right? Or could it be? Maybe even enough to mess with your sleep? I’m not going to spoil the answer, but let’s just say that after learning about the concept of a "half-life" today, you might be a little surprised.
So, what is a half-life? What’s the math behind it? And what does it have to do with the amount of caffeine left in your body at the end of the day … and even with calculating the ages of archeological artifacts and the entire solar system?
Let’s find out.
What Is a Half-Life?
Some types of atoms do a really weird thing—they spontaneously decay into other types of atoms. A bit more precisely, some unstable isotopes of certain atoms (meaning certain versions of certain atoms that have certain, shall we say, non-standard numbers of neutrons in their nuclei) will spontaneously turn into different elements and in so doing release other particles and light along the way.