Bottom line: Radiocarbon dating is a technique used by scientists to learn the ages of biological specimens from the distant past. It’s important that we allow God’s written record of history, the Bible, to guide our thinking about the past—this includes our understanding of the age of the Earth/universe How many times have you heard something like, “This animal lived 50,000 years ago”, or “This person died 20,000 years ago’?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.So something that lived (and died) when the proportion of C was less than normal would appear to have died more years ago than it actually did (for example, it might give an age of 3,000 years before the present, rather than its true age of 2,000 years).Even many archaeologists don’t think “carbon dating” is completely accurate all the time.
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.
In The Cosmic Story of Carbon-14 Ethan Siegel writes: The only major fluctuation [in carbon-14] we know of occurred when we began detonating nuclear weapons in the open air, back in the mid-20th century.
If you ever wondered why nuclear tests are now performed underground, this is why.
It can be used on objects as old as about 62,000 years. Atoms of the same element that have different numbers of neutrons are called isotopes. Most carbon on Earth exists as the very stable isotope carbon-12, with a very small amount as carbon-13.
Here’s an example using the simplest atom, hydrogen. Carbon-14 is an unstable isotope of carbon that will eventually decay at a known rate to become carbon-12.