Absolute dating science

By measuring the ratio of the amount of the original radioactive element to the daughter isotope, scientists can determine how many half-lives the element has undergone and from there can figure out the absolute age of the sample.The half-lives of several radioactive isotopes are known and are used often to figure out the age of newly found fossils.Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years.So in order to date most older fossils, scientists look for layers of igneous rock or volcanic ash above and below the fossil.

In other words, half (50%) of the Carbon-14 you started with has decayed into the daughter isotope Nitrogen-14.One method uses potassium 40 which decays to argon 40.The half life of potassium 40 is 1.3 billion years.Now that you know how many half-lives have passed for your fossil, you need to multiply your number of half-lives by how many years are in one half-life. Your fossil is of an organism (maybe human) that died 11,460 years ago.The universe is full of naturally occurring radioactive elements.

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