It is possible to measure the ratio of the different radioactive parent isotopes and their daughter isotopes in a rock, but the ratios are not dates or ages.
Most scientists and many Christians believe that the radiometric dating methods prove that the earth is 4.5 billion years old.
The textbooks speak of the radiometric dating techniques, and the dates themselves, as factual information.
There are three main assumptions that must be made to accept radiometric dating methods.
These must be accepted on faith in uniformitarian and naturalistic frameworks.
Relative ages are assigned to rocks based on the idea that rock layers lower in the strata were deposited before rock layers that are higher.
Creationists do not necessarily disagree with this concept, but it can only be applied to layers that are found in one location and/or can be determined to have been deposited in a continuous layer over a very wide area.
However, there are many methods that can be used to determine the age of the earth or other objects.
The textbooks focus on relative dating, based on the layering of the rocks, and radiometric dating.
The reason this age may not be a true age—even though it is commonly called an absolute age—is that it is based on several crucial assumptions.
Most radiometric dating techniques must make three assumptions: The major problem with the first assumption is that there is no way to prove that the decay rate was not different at some point in the past.
There is also a difference in the timescale used to explain the layers.