Fifth Post

Pitfalls of Radioactive Dating

Pax Christi, y'all, on this Gregorian Calendar Feria and Byzantine Calendar Feast of the Wonderworker Bishop of Amathunsa, Tychon!

Radioactive dating is a collection of Natural Science techniques used to determine the ages of things. Its use is prominent in Archeology as well as Historical Geology, and with its influence affecting Cosmology and, most importantly, how people generally think about things.

OK, first, the nuts and bolts of radioactivity:

— The nucleus of every atom of an atom has electrically positive particles called protons, their number determining the element’s identity (carbon, hydrogen, iron, etc.).

— Except for most hydrogen, the nucleus of each atom also contains electrically neutral particles called neutrons.

— An element can have differing numbers of neutrons and still be that element. E.g., carbon has six protons (which make it carbon), but can have six (most carbon atoms), seven, or even eight neutrons. Each group of atoms in an element that has a particular number of neutrons is called an ISOTOPE.

— Some isotopes of elements do not have stable nuclei (neutrons just don't get along with the arrangement of things).

— Unstable-nucleied isotopes are RADIOACTIVE.

— Radioactive isotopes’ nuclei “blow off steam” in three ways:

— First: GAMMA RAYS. Like X-rays (Y'all know dental X-rays.) on steroids. A strong energy release. Not good for your complexion, or anything else you have. Hard to block.

— Second: ALPHA PARTICLES. A helium nucleus (two protons, two neutrons) blasts out. Relatively easy to block. However, because two protons are gone, the remaining atom is now of a different element.

— Third: BETA PARTICLES. High-energy electrons. Middle of the road blockability. They are ejected from an unhappy neutron, which promptly turns into a proton and…drumroll please…changes the atom into a different element.

— The DECAY RATE is how quickly the radioactive isotope of an element (the PARENT element) changes into another element (the DAUGHTER element). These rates are easily measurable.

— The time necessary for half the parent element to change into something else is called its HALF-LIFE.

Now for the fun 🤡 part: RADIOACTIVE DATING.

The premise is straightforward: If, to use a very simplified example, I find a gram of radioactive uranium in aunt Gertrude's ornamental granite garden rock, along with a gram of the non-radioactive lead that it decays into, and I know that uranium has a half-life of a billion years, then that rock is a billion years old.

You measure these elements in mineral crystals like found in granite because their molecular lattice is very stable.

Sounds neat, huh?

Not so fast!!

We’ve got us an avalanche of background assumptions that need questioning in this example (which hold true for all examples), assumptions that need to be airtight if they're gonna be validly used. I’ll address them through questions:

— How do you know the initial amount of lead and radioactive uranium in the rock? Were you there?

— How do you know that the lead or uranium hadn't wandered in or out over a billion years, thus affecting the proportion you're measuring? Elements do wander in crystals from temperature differences, etc. (Yup, homework time! 😔)

--The biggie: how do you know that the radioactive decay rate - half-life - has always been constant? Has anyone tested the effects of high electric or magnetic fields (or variability of them), high temperatures, or other factors on these rates? (In nuclear reactors and in those hideous things we call nuclear bombs, the decay rate is majorly (reactors for electricity generation) or catastrophically (bombs) accelerated by the radioactive nuclei being bombarded by alpha particles etc. from nearby radioactive nuclei.)

— There are other assumptions connected specifically to radiocarbon dating (carbon-14), but they'll be in another post.

In a nutshell, how reliable is radioactive dating, really????

Our Mother of Perpetual Help, aid us!!

Ademar