What is the scientific concept behind carbon dating
What is the scientific concept behind carbon dating - Adult face time free chat
Read more on calibration and accuracy of radiocarbon dating.
The level of radiocarbon in the atmosphere has varied over time — it was about two per cent higher 3,500 years ago, possibly due to factors affecting cosmic rays (like changes in solar cycles or the Earth's magnetic field).And that something else starts where Earth meets space.Earth's upper atmosphere is constantly being bombarded by cosmic rays (usually protons travelling at nearly the speed of light).And after 11,460 years (two half-lives), only a quarter of the original carbon-14 atoms are left.After five half-lives (28,650 years) only 1/32 remains.The exact age of an unknown sample can never be known for sure, so short of discovering a time machine, 95 per cent accuracy is as good as it gets.
Radiocarbon may not be perfect, but as any single 30-something can attest, no dating method is.
It's not that the radioactive carbon in air or food doesn't decay, it does.
But something else is going on that keeps producing new carbon-14 — otherwise it would have all turned to nitrogen millions of years ago.
Chemically, carbon-14 is no different from non-radioactive carbon atoms, so it ends up in all the usual carbon places — one trillionth of the carbon atoms in air, plants, animals and us are radioactive.
All radioactive atoms eventually decay into something more stable, and carbon-14 decays into nitrogen.
So calculating the age range of a once-living sample involves measuring the 14C/12C ratio, and using this the known half-life to estimate the length of time since the sample died.