# Line graphs and radiometric dating

Also, such a calculation does not provide us with any statistical error margin to double-check the result.

This technique, which is used in virtually all disciplines of modern social science, physical science and engineering, is entirely straightforward, and computer software is widely available to do the requisite calculations and, in fact, is built in to most spreadsheet programs.

An important fact is that linear regression, in addition to giving the best fit of the slope of the line (which then leads immediately to the date), also gives a statistical confidence interval as to the possible error in the determination of the slope.

Radiometric dating is rooted in the rates of radioactive decay of various isotopes, which rates have been measured carefully in numerous laboratories beginning in the early 20th century.

Radioactive decay is in turn a very basic physical phenomenon, well understood as a consequence of quantum mechanics.

Some have said that young-earth creationists will not be convinced of the scientific ages of the earth and fossils until they can measure these dates with their own hands. As mentioned above, radiometric dating methods are the basis for the figures in the detailed charts of the geologic ages, an abbreviated version of which is shown above.

Some of the most commonly used radiometric schemes are [Dalrymple1991, pg. 55]: Each method has its own particular range of applicability, which derives from the half-life of the particular radioactive decay involved.

For example, the "SHRIMP" ion microprobe now in use in numerous laboratories around the world can reliably measure U-Pb and Pb-Pb ages from spots only 0.02 mm (i.e., 20 micrometers) in size within a zircon crystal [Dalrymple2004, pg. It should be emphasized, though, that even relatively unsophisticated equipment can perform radiometric measurements of dates fairly well.Of course, in real scientific research, scientists do not rely on manually drawing points on graph paper to determine a best-fit straight line or to determine the line's slope or y-intercept.Instead, they use a statistical technique known as linear regression, which computes the least-squares best fit of a straight line through a sequence of points.Along this line, a kickstarter-funded firm known as Consumer Physics has designed a handheld, consumer-oriented optical spectrometer, which can be used to measure the molecular constituents of an item (food items, etc.) that you shine its built-in light upon.This cannot be used for radiometric dating, but it does suggest advanced technology such as this is rapidly advancing and soon will be available to consumers.However, usually it is not possible to apply this formula directly, because, for instance, in many cases we do not know the original amount of the radioactive isotope when the rock was solidified.