of original isotope found in the rock. The absolute age of a specimen (fossil) or rock is

The absolute age of a specimen or rock refers to the exact age in years, providing a specific timeframe for when the rock or fossil was formed. This is typically determined using radiometric dating techniques, where scientists measure the ratios of parent isotopes to daughter isotopes within the minerals of the specimen or rock.

Common isotopes used in this context include Uranium-238, Carbon-14, and Potassium-40. The principle behind these techniques is based on the known half-life of these isotopes, which allows researchers to calculate how long it has been since the rock or fossil was formed based on the amount of parent and daughter isotopes present.

For example, in the case of Carbon-14 dating, which is effective for relatively recent organic materials (up to about 50,000 years old), the half-life of Carbon-14 is approximately 5,730 years. By measuring how much Carbon-14 remains in a fossil compared to Carbon-12, researchers can determine the time elapsed since the organism died.

Similarly, Uranium-238, which has a half-life of about 4.5 billion years, is used for dating older geological formations. Through these methods, scientists can establish a clearer timeline of Earth's history and the evolution of life on our planet. Thus, the absolute age is crucial for understanding geological processes and the history of life.