We know that elements can exist as isotopes, which means that their atomic nuclei contain the same number of protons but different numbers of neutrons.

This isotope Carbon-14 has a half life of 5,700 years.

So that's taking into account all the decays and all that stuff, this is a natural abundance. And that means that as time goes on, the carbon 14 abundance will decrease. So the amount that we've got at our time now is 0.5 times 10 to the -12.

So that means the carbon 14 abundance can tell us how long something's been dead. So let's see how we can use this to do a problem. It's bound to have a carbon 14 ratio that's only 0.5 times 10 to the -12. The initial amount when he died must have been 1.3 because he was interacting with its environment. Alright, so that means that t is going to be, I'm just going to solve this equation real quickly, it's going to be 5700 years times the natural log of 0.5 over 1.3 divided by the natural log of one half.

And if you type that in your calculator you'll find that this specimen is 700, oh sorry, 7860 years dead. So that's the way that we can do these calculations. Let's do it a different, let's do a different one.