It's "radiometric dating" and the rate of isotope decay is very consistent, and is not affected by environmental changes like heat, temperature, and pressure. This makes radiometric dating quite reliable. An error margin of 2–5% has been achieved. Radiometric dating of rocks and minerals using naturally occurring, long-lived radioactive isotopes is troublesome for young-earth creationists because the techniques have provided overwhelming evidence of the antiquity of the earth and life (NCSC, Chemical Geology).
Brent Dalrymple, a premier expert in the field., wrote [Dalrymple2004, pg. 80-81]:
"These methods provide valid age data in most instances, although there is a small percentage of instances in which even these generally reliable methods yield incorrect results. Such failures may be due to laboratory errors (mistakes happen), unrecognized geologic factors (nature sometimes fools us), or misapplication of the techniques (no one is perfect).
"We scientists who measure isotope ages do not rely entirely on the error estimates and the self-checking features of age diagnostic diagrams to evaluate the accuracy of radiometric ages. Whenever possible we design an age study to take advantage of other ways of checking the reliability of the age measurements. The simplest means is to repeat the analytical measurements in order to check for laboratory errors. Another method is to make age measurements on several samples from the same rock unit. This technique helps identify post-formation geologic disturbances because different minerals respond differently to heating and chemical changes. The isochron techniques are partly based on this principle.
"The use of different dating methods on the same rock is an excellent way to check the accuracy of age results. If two or more radiometric clocks based on different elements and running at different rates give the same age, that’s powerful evidence that the ages are probably correct."
Any argument that uses misinformation, chicanery and outright lies is itself a unfounded and not sound.
