In his article Light Attenuation and Exponential Laws in the last issue of Plus, Ian Garbett discussed the phenomenon of light attenuation, one of the many physical phenomena in which the exponential function crops up. In this second article he describes the phenomenon of radioactive decay, which also obeys an exponential law, and explains how this information allows us to carbon-date artefacts such as the Dead Sea Scrolls. In the previous article, we saw that light attenuation obeys an exponential law. To show this, we needed to make one critical assumption: that for a thin enough slice of matter, the proportion of light getting through the slice was proportional to the thickness of the slice. Exactly the same treatment can be applied to radioactive decay. However, now the "thin slice" is an interval of time, and the dependent variable is the number of radioactive atoms present, N t.
BioMath: Carbon Dating
Rationale The world will be filled of garbage and litter in the future. It is important to be aware of the time it will take for the organic materials to decay so we know the importance of the conservation of energy. Scientists can use the knowledge from carbon dating to predict and observe energy cycles in the environment. All the members have been in chemistry and are aware of this method. Used to estimate the age of organic materials like wood and leather. For organisms, can only be used to determine age of organism since death.
Common Era CE is one of the year notations used for the Gregorian calendar and its predecessor, the Julian calendar , the world's most widely used calendar era. The expression has been traced back to , when it first appeared in a book by Johannes Kepler as the Latin : annus aerae nostrae vulgaris year of our common era ,   and to in English as " Vulgar Era". Since the later 20th century, CE and BCE are popular in academic and scientific publications as culturally neutral terms.
Archaeologists use the exponential, radioactive decay of carbon 14 to estimate the death dates of organic material. The stable form of carbon is carbon 12 and the radioactive isotope carbon 14 decays over time into nitrogen 14 and other particles. Carbon is naturally in all living organisms and is replenished in the tissues by eating other organisms or by breathing air that contains carbon. At any particular time all living organisms have approximately the same ratio of carbon 12 to carbon 14 in their tissues. When an organism dies it ceases to replenish carbon in its tissues and the decay of carbon 14 to nitrogen 14 changes the ratio of carbon 12 to carbon