Should carbon dating be used to determine the age of rocks or fossils?

Author: BibleAsk Team


What is Carbon Dating?

Carbon dating, also known as radiocarbon dating, is a method used to determine the age of an object containing organic material by measuring the amount of carbon-14 it contains. Carbon-14 is a radioactive isotope of carbon, and it is produced in the Earth’s atmosphere through the interaction of cosmic rays with nitrogen atoms. This radioactive isotope is then absorbed by living organisms, including plants and animals, through processes like photosynthesis and consumption of other organisms.

While an organism is alive, it maintains a balance between the intake and decay of carbon-14. However, when the organism dies, it stops taking in carbon-14, and the isotope begins to decay at a known rate. The half-life of carbon-14 is approximately 5,730 years, which means that after this time, half of the original carbon-14 in a sample will have decayed into nitrogen-14.

By measuring the remaining amount of carbon-14 in a sample and comparing it to the initial amount of carbon-14 that the organism would have had when it was alive, scientists can estimate the time elapsed since the death of the organism. This technique is particularly useful for dating archaeological artifacts, fossils, and other organic materials that are on the order of thousands to tens of thousands of years old. However, carbon dating has limitations and is not suitable for dating materials older than about 50,000 years due to the diminishing amounts of carbon-14 in very old samples.

Does it work?

Some teach that radiocarbon dating proves billions of years. But scientists know it can’t, because as mentioned, carbon 14 decays too fast. So, after two half-lives, a quarter is left; after three half-lives, only an eighth; after 10 half-lives, less than a thousandth is left which means that after about 5 half-lives the difference is not measurable with any degree of accuracy.

Therefore, radiocarbon dating doesn’t work well on objects much older than twenty thousand years, because such objects have so little carbon 14 left that their beta radiation is taken out by the background radiation of cosmic rays and potassium 40 decay. But younger objects can easily be dated, because they still emit plenty of beta radiation, enough to be measured after the background radiation has been subtracted out of the total beta radiation.

How Old Is the Earth?

Patrick M. Hurley points out: “Without rather special developmental work, it is not generally practicable to measure ages in excess of about twenty thousand years, because the radioactivity of the carbon becomes so slight that it is difficult to get an accurate measurement above background radiation.” Hurley, Patrick M. 1959. How Old Is the Earth? New York: Doubleday & Co. p. 108.

Thus, carbon dating can’t be used to date rocks or fossils. It is only useful for once-living things which still contain carbon, like flesh or bone or wood. Rocks and fossils, consisting only of inorganic minerals, cannot be dated by this method.

In His service,
BibleAsk Team

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