How Many Parent Atoms?

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This week we’re looking at the assumptions behind radiometric dating. Here’s how it works.

Radiometric decay is the process where one element, called the “parent,” decays into a new element, called the daughter. The rate of this decay—and the number of daughter atoms found in the rocks—are used to try to date the rocks to millions of years.

Now, the first assumption is that we can know the conditions when the rock was formed. But, in most cases, no one was there to observe the rock being formed. Scientists just assume they can know the original number of parent atoms based on how many parent atoms are left—and how many daughter atoms are now present.

That’s unprovable!

Dig Deeper

• Radiometric Dating: Back to Basics
• Radiometric Dating: Problems with the Assumptions