Dating fossils using radioisotopes
Carbon-14 dating has been used successfully on the Dead Sea Scrolls, Minoan ruins and tombs of the pharaohs among other things. The half-life of carbon-14 is approximately 5,730 years. dinosaurs the evolution alleges lived millions of years ago.
Levels of carbon-14 become difficult to measure and compare after about 50,000 years (between 8 and 9 half lives; where 1% of the original carbon-14 would remain undecayed).
Inside an ionization detector is a small amount (perhaps 1/5000th of a gram) of americium-241.
The radioactive element americium has a half-life of 432 years, and is a good source of alpha particles.
This technique is widely used on recent artifacts, but educators and students alike should note that this technique will not work on older fossils (like those of the dinosaurs alleged to be millions of years old).
This technique is not restricted to bones; it can also be used on cloth, wood and plant fibers.
(The same ratio as in the atmosphere.) At the moment of death, no new carbon-14 containing molecules are metabolized, therefore the ratio is at a maximum.
After death, the carbon-14 to carbon-12 ratio begins to decrease because carbon-14 is decaying away at a constant and predictable rate.
The end result is that the growth of disease-causing microorganisms or those that cause spoilage are slowed or are eliminated altogether.
A computer uses this information to construct an image (called a PET scan) of the organ that is being examined.
PET scans have been used to study the effects of drugs on cancers, to measure damage in victims of stroke or heart attack, and to study chemical changes that occur during epileptic seizures..
This rules out carbon dating for most aquatic organisms, because they often obtain at least some of their carbon from dissolved carbonate rock.
The age of the carbon in the rock is different from that of the carbon in the air and makes carbon dating data for those organisms inaccurate under the assumptions normally used for carbon dating.
The rate of iodine-131 uptake, determined with a Geiger counter or other scanning device, indicates whether the thyroid glands are functioning properly.