Carbon dating and half life calculations

The barrel represents the earth's atmosphere in which the carbon-14 accumulates.The water leaking out the sides of the barrel represents the loss (mainly by radioactive decay) of the atmosphere's supply of carbon-14.Half-life is defined as the amount of time it takes a given quantity to decrease to half of its initial value.The term is most commonly used in relation to atoms undergoing radioactive decay, but can be used to describe other types of decay, whether exponential or not.Before we get into the details of how radiometric dating methods are used, we need to review some preliminary concepts from chemistry.Recall that atoms are the basic building blocks of matter.One of the most well-known applications of half-life is carbon-14 dating.The half-life of carbon-14 is approximately 5,730 years, and it can be reliably used to measure dates up to around 50,000 years ago.

The argument may be compared to filling a barrel which has numerous small holes in its sides.We know that it is older than Christendom, but whether by a couple of years or a couple of centuries, or even by more than a millenium, we can do no more than guess." [Rasmus Nyerup, (Danish antiquarian), 1802 (in Trigger, 19)].Nyerup's words illustrate poignantly the critical power and importance of dating; to order time.The process of carbon-14 dating was developed by William Libby, and is based on the fact that carbon-14 is constantly being made in the atmosphere.It is incorporated into plants through photosynthesis, and then into animals when they consume plants.Oakley (1979) suggested its development meant an almost complete re-writing of the evolution and cultural emergence of the human species.

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