Working my way through It Couldn’t Just Happen to prep for CC Challenge A this coming year…
I need another set of eyes to tell me if the explanation of carbon dating is correct:
p55 "…a certain percent of different radioactive elements slowly turn into other elements. Carbon 14 turns into Carbon 12."
p58 "Scientists assume that originally all the material in a radiometric sample was carbon 14 or rubidium or whatever. What if originally part of the material being measured was already carbon 12? … Since we do not know what was there originally, the dates may be very far from correct."
p58 “Experiments have shown that carbon 14, for instance, does change into carbon 12 at different rates, depending on factors like heat and radiation. Also, we know that high electric voltages definitely change the rate of decay of many elements.”
I thought it worked like this:
-there are several isotopes of carbon in the atmosphere
-living things exchange carbon with the atmosphere until they die at which point they do not take on any more carbon
-the carbon 14 undergoes radioactive decay to nitrogen 14
-the carbon 12 is stable and does not undergo decay
-measuring the amount of carbon 14 and carbon 12 in a sample and calculating the current ratio allows you to determine how long ago the organism died (since the ratio of carbon 14 to carbon 12 in the atmosphere does change some over time, you need to use a calibration curve…these are developed by measuring carbon ratios in tree rings and other once living things that can be dated by other methods)
I could not find anything about decay rates changing based on heat or radiation and the author gives no source so should I doubt that statement also??