"Everything which has come down to us from heathendom is wrapped in a thick fog; it belongs to a space of time we cannot measure.

The ratio of Carbon-14 remaining indicates the times since the death of a living substance.

Carbon-14 only works for things between 3 and 40 thousand years old. Carbon dating is based on an isotope of carbon, carbon 14, that's unstable. We breathe in carbon dioxide, we eat carbon, we take in carbon and so our bodies continually renewing our supply of carbon 14.

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.

It's always the same thing and if you're having trouble in going from this step to this step, make sure you know how to do that. We take the natural log of both sides and then we solve for t. Let's say that a specimen has been dead for 10,000 years and I want to know its carbon 14 ratio.