Replies

They do a good job of explaining the 1/2 life period, however, they fail to address the one crucial element that is rooted in the scientific method. Observation. Starting with Carbon 14, who has observed Carbon 14 decaying to 1/2 of its original component 5,730 years ago? How about Thorium 232 and 14 billion years?

"...they fail to address the one crucial element that is rooted in the scientific method. Observation. Starting with Carbon 14, who has observed Carbon 14 decaying to 1/2 of its original component 5,730 years ago? How about Thorium 232 and 14 billion years?..."

With all due respect, you're displaying a complete lack of understanding about radioactive decay processes, and how to measure their rates. Any chunk of matter you can see contains TRILLIONS of atoms. If these atoms are of the radioactive variety, some of them are ALWAYS POPPING OFF. You can measure and even "count" the decay events.

If you are dealing with a really unstable variety of atom, these "decay events" will be happening quite rapidly. If you are dealing with a more stable variety, the events will occur less frequently. You can measure the rate of the events, and calculate the amount of time it would take for 1/2 the sample to decay.

Now, while it is true that if you ISOLATED a SINGLE Thorium 232 atom and WATCHED JUST THAT ONE, it might take 14 billion years to see it fizzle. However, if you have a good sized chunk of Thorium 232, out of the zillions of atoms in the sample, some are ALWAYS popping.

Would you make the same foolish argument that NO ONE has sat and watched a 4000 year old redwood tree grow? How can you be SURE that it takes that long to grow such a tree? We do it because we OBSERVE zillions of other specimans at different stages in their lifecycle. (well, in the case of trees, it is not zillions, but a whole forest full, anyway).

There is more than one way to measure the time it takes something to occur than to sit and watch just one speciman.

Well, you could read the original paper,

Arnold, J. R., & Libby, W. F. (1949). Age Determinations by Radiocarbon Content: Checks with Samples of Known Age. Science, 110, 678-680.

but basically they compared their computed results to a “curve of knowns” (historically verified objects). Libby recognized an error and revised the method to arrived at the Cambridge Half-life (5730+/-40).

I don't know about thorium 232, but comparing the ratio of uranium 234 and thorium 230 is used as a dating method (one is soluble, the other is not).