When an organism, eg a tree, dies it stops taking in carbon dioxide.

The amount of carbon-14 in the wood decreases with time as it decays into nitrogen with a half-life of about 5700 years.

When it decays it forms thorium-234 which is also unstable.

Following a conference at the University of Cambridge in 1962, a more accurate figure of 5730 years was agreed upon and this figure is now known as the Cambridge half-life.

Carbon dating is used to determine the age of biological artifacts up to 50,000 years old.

Carbon-14 dating has been used successfully on the Dead Sea Scrolls, Minoan ruins and tombs of the pharaohs among other things. The half-life of carbon-14 is approximately 5,730 years. dinosaurs the evolution alleges lived millions of years ago.

Levels of carbon-14 become difficult to measure and compare after about 50,000 years (between 8 and 9 half lives; where 1% of the original carbon-14 would remain undecayed).

The amount of carbon-14 in the atmosphere has not changed in thousands of years.

Even though it decays into nitrogen, new carbon-14 is always being formed when cosmic rays hit atoms high in the atmosphere.

The highest rate of carbon-14 production takes place at altitudes of 9 to 15 km (30,000 to 50,000 ft).

At high geomagnetic latitudes, the carbon-14 spreads evenly throughout the atmosphere and reacts with oxygen to form carbon dioxide.

Carbon dioxide also permeates the oceans, dissolving in the water.

Plants take in atmospheric carbon dioxide by photosynthesis, and are ingested by animals.

This technique is widely used on recent artifacts, but educators and students alike should note that this technique will not work on older fossils (like those of the dinosaurs alleged to be millions of years old).