For example, a problem I have worked on involving the eruption of a volcano at what is now Naples, Italy, occurred 38500 years ago with a plus or minus of 300 years.
So, when the materials are appropriate and one carefully avoids contamination and re setting radiometric clocks can be VERY ACCURATE.
: Suppose there is a set of variables whose individual values are probably different, and may be anything larger than zero. If there is a group of radioisotopes whose eventual decay is not predictable on the individual level, I do not understand how a decay constant is measurable.
Different methods of radiometric dating vary in the timescale over which they are accurate and the materials to which they can be applied.
They arrived at this conclusion by comparing age estimates obtained using two different methods - analysis of radioactive carbon in a sample and determination of the ratio of uranium to thorium in the sample.
In some cases, the latter ratio appears to be a much more accurate gauge of age than the customary method of carbon dating, the scientists said.
For example, the element Uranium exists as one of several isotopes, some of which are unstable.
When an unstable Uranium (U) isotope decays, it turns into an isotope of the element Lead (Pb).
It is too soon to know whether the discovery will seriously upset the estimated dates of events like the arrival of human beings in the Western Hemisphere, scientists said.