Uranium lead dating accuracy
Their results were 'two to three times less accurate than implied by the range of error they stated.' They thought the variations might have been caused by poor laboratory standards allowing contamination of the samples.Some scientists believe the problem runs far deeper than this, as the following quote shows: In the light of what is known about the radiocarbon method and the way it is used, it is truly astonishing that many authors will cite agreeable determinations as "proof" for their beliefs...But in actual practice, we know neither the original ratios nor if the specimen has been contaminated and are forced to make what we hope are reasonable assumptions.The tiny initial amount of C14, the relatively rapid rate of decay (the half-life of C14 is currently about 5700 years) and the ease with which samples can become contaminated make radiocarbon dating results for samples "older" than about 50,000 years effectively meaningless.As you might guess, radioactive carbon (C) is quite rare.Only one out of every trillion carbon atoms is C14. The C14 created in the upper atmosphere reacts with oxygen to become carbon dioxide.The ions produced are forced into a magnetic field where the different mass of the carbon isotopes causes a different deflection, allowing the quantity of each isotope to be measured.This method is claimed to be more accurate than the older and slower method of counting the number of radioactive decay emissions from a quite large sample.
If we know what the original ratios of C14 to C12 were in the organism when it died, and if we know that the sample has not been contaminated by contact with other carbon since its death, we should be able to calculate when it died by its C14 to C12 ratio.
The radioactive carbon has six protons and eight neutrons in its nucleus, giving it a total atomic mass of 14.
This atom is not stable, and will break down, releasing nuclear energy in the process.
It is the supposed accuracy of the new method that allows measurements sensitive enough to date objects claimed to be more than twenty or thirty thousand years old.
A recent test by the British Science and Engineering Research Council has shown that the accuracy of the new technique is greatly overrated.