Recall that atoms are the basic building blocks of matter.
Atoms are made up of much smaller particles called protons, neutrons, and electrons.
Age determinations can also be obtained from carbonate deposits such as calcite, dissolved carbon dioxide, and carbonates in ocean, lake, and groundwater sources.
Cosmic rays enter the earth's atmosphere in large numbers every day and when one collides with an atom in the atmosphere, it can create a secondary cosmic ray in the form of an energetic neutron.
If you want to go even further back, you can look at cave deposits, and the fancy word for these cave deposits are speleothems. But the reason why these are useful is these are formed by calcium carbonate, so they have carbon in them, and slowly over, really, tens of thousands of years, the water in the cave deposits that calcium carbonate.
C-14 is produced in the upper atmosphere when nitrogen-14 (N-14) is altered through the effects of cosmic radiation bombardment (a proton is displaced by a neutron effectively changing the nitrogen atom into a carbon isotope).
The new isotope is called "radiocarbon" because it is radioactive, though it is not dangerous.
This has caused many in the church to reevaluate the biblical creation account, specifically the meaning of the word “day” in Genesis 1.
With our focus on one particular form of radiometric dating—carbon dating—we will see that carbon dating strongly supports a young earth.