Problems with radio carbon dating dating men older
Organisms at the base of the food chain that photosynthesize – for example, plants and algae – use the carbon in Earth’s atmosphere.They have the same ratio of carbon-14 to carbon-12 as the atmosphere, and this same ratio is then carried up the food chain all the way to apex predators, like sharks.Because the ratio of carbon 12 to carbon 14 present in all living organisms is the same, and because the decay rate of carbon 14 is constant, the length of time that has passed since an organism has died can be calculated by comparing the ratio of carbon 12 to carbon 14 in its remains to the known ratio in living organisms.In the late 1940s, American chemist Willard Libby developed a method for determining when the death of an organism had occurred.But when gas exchange is stopped, be it in a particular part of the body like in deposits in bones and teeth, or when the entire organism dies, the ratio of carbon-14 to carbon-12 begins to decrease.The unstable carbon-14 gradually decays to carbon-12 at a steady rate. Scientists measure the ratio of carbon isotopes to be able to estimate how far back in time a biological sample was active or alive.As we mentioned above, the carbon-14 to carbon-12 ratio in the atmosphere remains nearly constant.
A detailed description of radiocarbon dating is available at the Wikipedia radiocarbon dating web page.
Radiocarbon dating uses isotopes of the element carbon. Cosmic rays – high-energy particles from beyond the solar system – bombard Earth’s upper atmosphere continually, in the process creating the unstable carbon-14. Because it’s unstable, carbon-14 will eventually decay back to carbon-12 isotopes.
Because the cosmic ray bombardment is fairly constant, there’s a near-constant level of carbon-14 to carbon-12 ratio in Earth’s atmosphere.
The history of radiocarbon dating goes back to 1949, where it was introduced to the world by Willard Libby.
Radiocarbon dating is technique that uses the decay of carbon-14 to estimate the age of organic material.