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Radiometric dating (view source)
Revision as of 19:35, September 22, 2019
, 19:35, September 22, 2019Try to explain why it's hard, and what one needs to be careful about.
Because radiometric dating fails to satisfy standards of testability and [[falsifiability]], claims based on radiometric dating may fail to qualify under the ''[[Daubert]]'' standard for court-admissible scientific evidence. It is more accurate for shorter time periods (e.g., hundreds of years) during which control variables are less likely to change.
Because radiometric dating fails to satisfy standards of testability and [[falsifiability]], claims based on radiometric dating may fail to qualify under the ''[[Daubert]]'' standard for court-admissible scientific evidence. It is more accurate for shorter time periods (e.g., hundreds of years) during which control variables are less likely to change.
== Basic mechanism ==
Radiometric dating proceeds from the fact that certain substances (radioactive isotopes) decay, with near-clockwork accuracy, into other elements, and that the old elements and the new elements can be chemically distinguished and can be quantitatively measured. Even the individual isotopes of an element can be accurately measured, though they can't be chemically separated. The radioactive decay of a given isotope proceeds by a well-known [[Radioactivity#Exponential_decay_and_half-life|exponential decay function]] involving a "half-life" for that isotope:
::<math>e^{-\frac{log(2)}{H}\ t}</math>
where H is the half-life.
So, as a totally implausible and fictional oversimplification, if we had compelling reason to believe that some sample consisted of 100% Uranium-238 at some era that we are interested in, like the Permian-Triassic boundary, and it now consists of 96.2% Uranium and 3.8% Lead-206, we could conclude that the event took place 250 million years ago. (It did, but that is not the reason we know this.)
There are other radioactive decays that are used in radiometric dating, involving Carbon, Nitrogen, Potassium, Argon, Thorium, Rubidium, Strontium, and others. In practice, unlike the oversimplified scenario described above, there are several "radiometric clocks" ticking simultaneously, and it takes a lot of painstaking work for scientists to pick out the various decays. Also, analysis of the isotopes of the decay products can help determine what series the product came from. The Uranium-Lead series produces Lead-206, whereas the Thorium-Lead series produces Lead-208. And primordial Lead, that is, away from any radioactive decay, has a characteristic isotope mix of 204, 206, 207, and 208. Analysis of this will show which series the Lead came from.
== Assumptions and pitfalls ==
Needless to say, radiometric dating is not easy. It requires very careful measurement and analysis technique, as well as careful analysis of the assumptions, about such things as the purity and composition of the samples, to do this effectively. There are also assumptions about the accuracy of the equipment involved, and, of course, assumptions about the fundamental physics involved. The findings of the scientific community, on such things as the age of the Earth and the dates of various epochs (e.g. Permian, Triassic, Cretaceous, Paleogene) are the result of decades of measurement and analysis by hundreds of people.
== Key implausible assumptions ==
== Key implausible assumptions ==
==See also==
==See also==
*[[Radioactivity]]
*[[Essay:Radiometric dating - a non-Creationist Perspective]]
*[[Essay:Radiometric dating - a non-Creationist Perspective]]
*[[Literalist Bible chronology]] ''cites examples of radiometric dating results of artifacts which support a literalist dating of Biblical events such as the Exodus in'' 1577 B.C.
*[[Literalist Bible chronology]] ''cites examples of radiometric dating results of artifacts which support a literalist dating of Biblical events such as the Exodus in'' 1577 B.C.