Using this technique, called radiometric dating, scientists are able to "see" back in time.
Scientists use a technique called radiometric dating to estimate the ages of rocks, fossils, and the earth.
But for humans whose life span rarely reaches more than 100 years, how can we be so sure of that ancient date? Even the Greeks and Romans realized that layers of sediment in rock signified old age.
Other forms of radioactive dating are based on igneous rocks.
Since fossils are always found in sedimentary rocks these forms of radioactive dating can not be used in sedimentary layers.
With our focus on one particular form of radiometric dating—carbon dating—we will see that carbon dating strongly supports a young earth.
Note that, contrary to a popular misconception, carbon dating is not used to date rocks at millions of years old.
Measuring the uranium-to-lead ratios in the oldest rocks on Earth gave scientists an estimated age of the planet of 4.6 billion years.
Segment from A Science Odyssey: "Origins."Geologists have calculated the age of Earth at 4.6 billion years.
Igneous incursions into sedimentary layers can be dated using Uranium decay. Again small changes in the amount of Uranium or the amount of Lead can lead to large differences in the estimated age of the igneous layers.
Also the calculation are based on assumptions that the layer started with no lead and 100% uranium and no erosion has occurred.
Certain isotopes are unstable and undergo a process of radioactive decay, slowly and steadily transforming, molecule by molecule, into a different isotope.
This rate of decay is constant for a given isotope, and the time it takes for one-half of a particular isotope to decay is its radioactive half-life.
Many people have been led to believe that radiometric dating methods have proved the earth to be billions of years old.