Carbon Dating

Syllabus: General Studies Paper 3

A district court in Varanasi allowed a petition seeking carbon dating of the structure inside the Gyanvapi mosque that the Hindu side has claimed is a ‘Shivling’. 

What is carbon dating?

• Carbon dating is a widely-used method applied to establish the age of organic material, things that were once living. 
• Living things have carbon in them in various forms. 
• The dating method makes use of the fact that a particular isotope of carbon called C-14, with an atomic mass of 14, is radioactive, and decays at a rate that is well known.
• The most abundant isotope of carbon in the atmosphere is carbon-12 or a carbon atom whose atomic mass is 12. 
• A very small amount of carbon-14 is also present. 
• The ratio of carbon-12 to carbon-14 in the atmosphere is almost static, and is known.
• This method was developed by the American physicist Willard F. Libby about 1946.
• Carbon-14 is continually formed in nature by the interaction of neutrons with nitrogen-14 in the Earth’s atmosphere.

Plants get their carbon through the process of photosynthesis, while animals get it mainly through food. Because plants and animals get their carbon from the atmosphere, they too acquire carbon-12 and carbon-14 isotopes in roughly the same proportion as is available in the atmosphere.

The half-life concepts:

• Carbon-14 has a half-life of 5,730 ± 40 years—i.e., half the amount of the radioisotope present at any given time will undergo spontaneous disintegration during the succeeding 5,730 years.
• Because carbon-14 decays at this constant rate, an estimate of the date at which an organism died can be made by measuring the amount of its residual radiocarbon.

Its uses:

• It has proved to be a versatile technique of dating fossils and archaeological specimens from 500 to 50,000 years old.
• The method is widely used by geologists, anthropologists, archaeologists, and investigators in related fields.