What is Carbon Dating?

          Man’s curiosity has always led to the opening of new vistas in every field thus contributing to the development of science and widening the sphere of knowledge. And the curiosity of man to determine the age and period of existence of different objects that were once alive resulted in the technique of carbon dating. Through carbon dating process the age of different fossils of ancient plants and animals can be determined by finding out how long ago they lived.

          Radio-carbon and carbon-14 dating are two other names used for carbon dating. Now comes the question: what is this process and how does it help to estimate the age of the objects?

          Like all materials, carbon is made up of atoms. A small fraction of all carbon atoms are distinct from the others in the sense that they are radioactive and hence unstable. These atoms have 13 to 14 particles whereas the majority contains 12 particles. Carbon-14 is radioactive because it is unstable and breaks down, or decays very slowly into other elements. After the break up, they give up a burst of nuclear radiation.

          There is a regular intake of fresh supply of carbon from the atmosphere by all living things. They get rid of some carbon every time they breathe out but when they die some carbon is trapped inside. Some of the trapped carbon is radioactive, the most prominent being carbon-14. The carbon-14 inside them begins to decay at a constant rate. The age of the object is discovered by measuring the amount of carbon-14 still contained in the object. Age is estimated by working out how long ago death occurred. Archaeologists follow this process while determining the age of the objects discovered by them. The method is explained in the following paragraph.

          The time taken for half the atoms in any quantity of a radioactive substance to decay is called half-life of the substance. For example, when a tree is cut down, it ceases to acquire further carbon-14 atoms. Therefore, by comparing the radioactivity of a modern piece of wood with that of a specimen of some unknown age, the length of time that has elapsed since the latter’s death can be estimated.

          It is interesting to note that earlier the dating of some rocks were determined by scientists by observing the Uranium 238 element present in the rocks. The element Uranium 238 is known to have a half-life of 4,500 million years. It means that a given quantity of the material will be reduced by one-half in 4,500 million years. The age of the stones or rocks which contain Uranium 238 can be determined directly. But the radio-carbon process has replaced this method now.

          The age of old bones, wood, mummies and even old cloth (because the fibers come from dead plants) are estimated this way.