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How do we know how long ago dinosaurs lived?




How was the dinosaur age determined? How do scientists know how old a particular artefact is? The answer lies in the method of ‘carbon dating'. But, what is this carbon dating ?




Science of carbon dating


Carbon dating is used to determine the age of organic materials. In the atomosphere, cosmic rays react with nitrogen, producing the C14 isotope . This C14 isotope then reacts with oxygen and is absorbed by plants during photosynthesis. This C14 is consumed by animals thorugh plants. C14 is not stable isotope of carbon,which means amount of C14 present in animal's body decreases with time.


There is one more isotope of carbon known as C12 . This isotope of carbon is stable. So scientists came up with an excellent idea. They proposed that "if we can calculate the ratio between c14 and C12 we can determine how many years ago that organism died." And that’s how the method of ‘carbon dating’ was born.This sentence is over 30 syllables. Consider shortening it.



Applications of carbon dating


Carbon dating has a wide range of applications other than finding the death date of some dinosaurs! It can be used to predict the year of a particular painting. One of the earliest uses of carbon dating in history was in 1950, when Libby and his team dated samples from the Egyptian Old Kingdom. They were able to establish a chronology of the pharaohs based on the ages of the materials they found in their tombs. This allowed historians to refine their understanding of Egyptian history and culture, as well as the broader history of the ancient world.


It was evident that Brahmagupta introduced zero as a number in 628 A.D. But scientists found one manuscript named 'Bakhshali'. It is believed that one farmer found that manuscript while farming in 1881, Pakistan. In ‘Bakhshali’ , zero was mentioned as a symbol. When scientists did carbon dating of this manuscript, they found that some pages of Bakhshali were inscribed between the years 224 A.D. and 383 A.D.




Limitations of Carbon dating


Though carbon dating is a brilliant method to find the age of organic materials, there are some drawbacks. Carbon dating is only accurate for materials that are 50,000 years old. Beyond that range, the method of carbon dating fails. In carbon dating, samples need to be cleaned. But as we know, we can’t expect all organic materials to be clear. Scientists have to remove impurities from organic material to get an accurate age range for the product. The most important thing is that carbon dating can only be used on organic materials. We can’t find the age of any inorganic material using the carbon dating method.


To tackle these problems , scientists introduced another method. Eg. the uranium-lead method, potassium-argon dating, ,etc .These methods are used to predict the age of rocks and minerals. Dendrochronology is the method used to determine the age of wood. Development in these fields of science will definitely help us get to know our earth and universe better.

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