Ok, we'll change subjects.
Carbon dating is based on the idea that the ratio of unstable carbon-14 to stable carbon-12 in the atmosphere is approximately constant. Living things exchange carbon continuously with the atmosphere and so they have the same isotopic ratio. When they die, they stop breathing, and stop exchanging carbon with the air; so the carbon-14 then decays steadily away. When we find old biomass - wood, for instance, or leather - we can measure the ratio of carbon-14 to carbon-12 in it, and thereby work out how long ago it was alive.
The constant ratio of atmospheric isotopes is not certain, but it's likely, unless there's a major change in cosmic ray flux. At any rate, carbon dating agrees with known ages when we try it on objects of known provenance (like, say, an Egyptian pharaoh's sarcophagus where we already know the date), so we can calibrate against that. We're actually causing trouble for future archaeologists ourselves, by digging up huge quantities of ancient carbon and pumping it into the atmosphere, and thereby skewing the ratio in the atmosphere heavily in favour of carbon-12. They'll think our artefacts are rather older than they really are, and get terribly confused.
Carbon dating doesn't work on objects that are so old that there's very little carbon-14 left, so it's really best used for artefacts not more than a few tens of thousands of years old.
Older objects need a different method, and there are several. They're generally based on the idea that element A decays into element B at a known constant rate; a particular type of crystal C found in the rock is composed only of a compound of element A, not element B at all; so when we find element B in such a crystal we can be sure it came from decay of element A, and by the proportions in the crystal we can work out an age. The decay of uranium into lead is the longest-term clock we use, and that's how the age of 4.5 billion years or so is worked out for the Earth.
It's not something someone just made up one day.
Answers to Creationist Attacks on Carbon-14 Dating | NCSE