Radio-Carbon Dating Explained:
Carbon dating is a radiometric dating method, which uses Carbon -14 (a naturally occurring radioactive isotope of carbon). This method can be used to date carbonaceous materials (substances which are rich in carbon), by using applied physics theory such as half-life.
The technique was developed at the University of Chicago n 1949 and its developer Willard Libby won a Nobel Prize in Chemistry for his research and theory.
The most common use of carbon dating is to find the age of organic remains (often human or animal) from archaeological sites. This process has been used to date things such as; the ancient footprints of Acahualinca, Chauvet Cave, Dolaucothi, Haraldskaer Woman, Kennewick man, Skeleton Lake, Shroud of Turin, Thera Eruption and the Vinland Map. (try searching each on Wikipedia or Google for more information, very interesting if you like history)
Carbon-14 is a radioactive atom with 8 Neutrons and 6 Protons, which decays with a half life of 5730 years, which equates to; 2,092,882 days / 50,229,180 hours / 3,013,750,800 minutes or 180,825,048,000 seconds. (5730 x 365.25 x 24 x 60 x 60).
Other isotopes of carbon, which exist in nature, are Carbon-12 and Carbon-13 both of which are stable.
There are traces of Carbon-14 on earth and in its atmosphere, considering the half life of 5730 years, the amounts present at the beginning of the earth would no be long gone, so why is it still here? Nitrogen. Nitrogen is the makes up around 78% of the earths atmosphere, and cosmic rays collide with the particles in our atmosphere. The result of this is a nuclear reaction in the Nitrogen particles:
Nitrogen (14, 7) + Neutron = Carbon (14,6) + Proton
This reaction takes place mainly around altitudes of 9 15 km above the earth.
Plants use Photosynthesis to create food, they do this by absorbing carbon dioxide from the atmosphere. In this is a very small amount of Carbon-14 (one part per trillion). These plants now effectively contain a radioactive tracer, which can be measured using half-life. Plants are eaten by animals and as such every living thing contains Carbon-14 and exchanges it with its environment as long as it lives.
Carbon dating can be used to measure materials up to around 60,000 years old. The amount of Carbon-14 in an organism is approximately the level of the amount in the atmosphere (exact values can be found in laboratories), the amount of this isotope remaining will be a fraction of the original, decaying at an exponential rate, if we know the half life of Carbon-14, we can find what fraction of the isotope remains and find out how many half-lives it has been through, therefore finding its age.
Half live equation:
N = N0 e- t
N0 = number of radiocarbon atoms at t = 0, i.e. the origin of the disintegration time,
N = number of radiocarbon atoms remaining after radioactive decay during the time t = radiocarbon decay or disintegration constant.
One Half life
T1/2 = ln2 /