(June 9, 2025 at 6:26 pm)Paleophyte Wrote:(June 9, 2025 at 5:53 pm)SubtleVirtue Wrote: How do you know the decay rate for anything besides carbon 14...
Stick a lump of it in a very well-shielded lab with a radiation detector and watch it tick. Amusingly, the shielding isn't to keep the radiation in, it's to keep it out. You want to measure relatively small amounts of radiation without getting confounding readings from every stray cosmic ray, weapons test, and RBMK, so you frequently see these facilities built deep underground. You'll see some creationist sites claiming that all geological isotopes are calibrated against one another, and that truly would be circular, but that simply isn't how it's done. If you want to know the decay rates for Uranium you ask the boys at Oak Ridge.
Quote:we know that the carbon 14 is from the radiation hiting the atmosphere but where does the radio isotopes come from from the other processes?
There are a few others like tritium, 10-Be, and 36-Cl that are also cosmogenic, similar to 14-C. Most of the rest are primordial, they were formed by the dying stars that fertilized the nebula that became our solar system. "We are all made of recycled nuclear waste" is so much less poetic than being made of stardust. The funny thing is you only find very long-lived isotopic systems, which tells you a lot about the age of the Earth right there.
if most of the tests are based on 'stardust' isotopes... how does that date the rocks in an eruption?
