Start What radioactive decay is used in carbon dating

What radioactive decay is used in carbon dating

Public reaction to Three Mile Island was way overboard from what the actual event warranted as you can see from the banana equivalent dose.

If you were around ten miles away from the reactor during the accident, you’d have received about 8 millirems or about the equivalent of 800 bananas.

There are no known deaths/cancers/etc that resulted from this event.

The three key underlying assumptions are 1) the rate of decay of parent into daughter has remained constant throughout the unobservable past; 2) the specimen which we are examining hasn’t been contaminated in any way (that is, no parent or daughter has been added or taken away at any point during the unobservable past), and 3) we can determine how much parent and daughter were present at the beginning of the decay process – not all of the Pb206 present today necessarily came from decaying U238; Pb206 may have been part of the original constitution of the specimen.

If any of these assumptions are wrong, the method cannot accurately determine the age of a specimen.

In this case, U238 is the “parent” and Pb206 is the “daughter.” Scientists begin by measuring how long it takes for a parent isotope to decay into a daughter isotope.

In this particular case, it takes 4,460,000,000 years for half of a sample of U238 to decay into Pb206.

By measuring the amount of uranium and ‘radiogenic lead’ in these crystals, one can calculate that, if the decay rate has been constant, about 1.5 billion years must have passed.

(This is consistent with the geologic ‘age’ assigned to the granites in which these zircons are found.) There is a significant amount of helium from that ‘1.5 billion years of decay’ still inside the zircons.

Question: "How does radiometric dating fit with the view of a young earth?

" Answer: Radiometric dating does not fit with the “young earth” view.

…Results show that because of all the helium still in the zircons, these crystals (and since this is Precambrian basement granite, by implication the whole earth) could not be older than between 4,000 and 14,000 years.