Types of isotope dating
Since the half-life of carbon-14 is 5730 years, scientists can measure the age of a sample by determining how many times its original carbon-14 amount has been cut in half since the death of the organism.
For example, an object with a quarter of its original amount (2x1/2) should be roughly 11,460 years old.
Scientists discovered that rocks could be timepieces -- literally.
Many chemical elements in rock exist in a number of slightly different forms, known as isotopes.
This means that lifeless organic matter is effectively a closed system, since no carbon-14 enters the organism after death, an occurrence that would affect accurate measurements.
In radiometric dating, the decaying matter is called the parent isotope and the stable outcome of the decay is called the daughter product.
After all, the ever-changing Earth rarely left a complete geological record.For the isotopes uranium-235 and uranium-238 to respectively become lead-207 and lead-206, they must first undergo a serious of highly unstable transformations into isotopes with very short half-lives.However, if one knows the scientific formula for interpreting these transitions, the results can be "highly precise" according to paleontologist Guy Narbonne (Kerr, 789).The age of the planet, though, was important to Charles Darwin and other evolutionary theorists: The biological evidence they were collecting showed that nature needed vastly more time than previously thought to sculpt the world.A breakthrough came with the discovery of radioactivity at the beginning of the 1900s.
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Using this technique, called radiometric dating, scientists are able to "see" back in time.