How reliable is radiocarbon dating?
The half life of carbon is about 5, years, so if we measure the proportion of The trouble is that after 40, years there is under 1% of the original C left, and it With our current kit K years is about the limit. a huge age error in an old sample with a very small amount of carbon 14 present. Carbon dating is used to determine the age of biological artifacts. difficult to measure and compare after about 50, years (between 8 and 9 half lives; in the air and makes carbon dating data for those organisms inaccurate under the Carbon dating cannot be used on most fossils, not only because they are almost . Q: Unreliable carbon dating puts dinosaur bones over years old stopped taking in carbon derived from the atmosphere up to about 50, years ago when and some persisted for hundreds of thousands of years after the event.
From Nature magazine The carbon clock is getting reset. Climate records from a Japanese lake are set to improve the accuracy of the dating technique, which could help to shed light on archaeological mysteries such as why Neanderthals became extinct. Carbon dating is used to work out the age of organic material — in effect, any living thing. The technique hinges on carbon, a radioactive isotope of the element that, unlike other more stable forms of carbon, decays away at a steady rate.
Organisms capture a certain amount of carbon from the atmosphere when they are alive. By measuring the ratio of the radio isotope to non-radioactive carbon, the amount of carbon decay can be worked out, thereby giving an age for the specimen in question.
But that assumes that the amount of carbon in the atmosphere was constant — any variation would speed up or slow down the clock.
nuclear physics - Why is carbon dating limit only 40, years? - Physics Stack Exchange
The clock was initially calibrated by dating objects of known age such as Egyptian mummies and bread from Pompeii; work that won Willard Libby the Nobel Prize in Chemistry.
Various geologic, atmospheric and solar processes can influence atmospheric carbon levels. Since the s, scientists have started accounting for the variations by calibrating the clock against the known ages of tree rings. The assumptions are similar to the assumptions used in carbon dating. The mathematical premise undergirding the use of these elements in radiometric dating contains the similar confounding factors that we find in carbon dating method.
Most scientists today believe that life has existed on the earth for billions of years. This belief in long ages for the earth and the evolution of all life is based entirely on the hypothetical and non-empirical Theory of Evolution.
All dating methods that support this theory are embraced, while any evidence to the contrary, e. Prior to radiometric dating, evolution scientists used index fossils a.
A paleontologist would take the discovered fossil to a geologist who would ask the paleontologist what other fossils searching for an index fossil were found near their discovery. If it sounds like circular reasoning, it is because this process in reality is based upon circular reasoning. Henry Morris as follows: These long time periods are computed by measuring the ratio of daughter to parent substance in a rock, and inferring an age based on this ratio.
This age is computed under the assumption that the parent substance say, uranium gradually decays to the daughter substance say, leadso the higher the ratio of lead to uranium, the older the rock must be. While there are many problems with such dating methods, such as parent or daughter substances entering or leaving the rock, e. Geologists assert that generally speaking, older dates are found deeper down in the geologic column, which they take as evidence that radiometric dating is giving true ages, since it is apparent that rocks that are deeper must be older.
But even if it is true that older radiometric dates are found lower down in the geologic column which is open to questionthis can potentially be explained by processes occurring in magma chambers which cause the lava erupting earlier to appear older than the lava erupting later. Lava erupting earlier would come from the top of the magma chamber, and lava erupting later would come from lower down.
A number of processes could cause the parent substance to be depleted at the top of the magma chamber, or the daughter product to be enriched, both of which would cause the lava erupting earlier to appear very old according to radiometric dating, and lava erupting later to appear younger.
Other possible confounding variables are the mechanisms that can alter daughter-to-parent ratios. We can see that many varieties of minerals are produced from the same magma by the different processes of crystallization, and these different minerals may have very different compositions. It is possible that the ratio of daughter to parent substances for radiometric dating could differ in the different minerals.
Clearly, it is important to have a good understanding of these processes in order to evaluate the reliability of radiometric dating. Other confounding factors such as contamination and fractionation issues are frankly acknowledged by the geologic community, but are not taken into consideration when the accuracy and validity of these dating methods are examined.
The following quotation from Elaine G. Kennedy addresses this problem. Contamination and fractionation issues are frankly acknowledged by the geologic community.
For example, if a magma chamber does not have homogeneously mixed isotopes, lighter daughter products could accumulate in the upper portion of the chamber.
If this occurs, initial volcanic eruptions would have a preponderance of daughter products relative to the parent isotopes. Such a distribution would give the appearance of age. As the magma chamber is depleted in daughter products, subsequent lava flows and ash beds would have younger dates.
It does suggest at least one aspect of the problem that could be researched more thoroughly. The problems inherent in radiometric dating often cause them to be so unreliable that they contradict one another rather than validating each other. It would really be nice if geologists would just do a double blind study sometime to find out what the distributions of the ages are. In practice, geologists carefully select what rocks they will date, and have many explanations for discordant dates, so it's not clear how such a study could be done, but it might be a good project for creationists.
There is also evidence that many anomalies are never reported. There are so many complicated phenomena to consider like this that it calls the whole radiometric dating scheme into question. Only then can you gauge the accuracy and validity of that race.
We need to observe when the race begins, how the race is run are there variations from the course, is the runner staying within the course, are they taking performance enhancing drugs, etc. All bases must be covered if we are going to accurately time the race. This is the major flaw in radiometric dating, e.
Secondly, you must have an observable time span so we can be certain nothing has affected the amount of the radioactive element being measured, e.