Radiometric dating disproved
Those isotopes that are not stable decay into daughter nuclei.
Radiocarbon dating can easily establish that humans have been on the earth for over twenty thousand years, at least twice as long as creationists are willing to allow.
This is consistent with the assumption that each decay event is independent and its chance does not vary over time.
Here I want to concentrate on another source of error, namely, processes that take place within magma chambers.
Symbolically, the process of radioactive decay can be expressed by the following differential equation, where N is the quantity of decaying nuclei and k is a positive number called the exponential decay constant.
The meaning of this equation is that the rate of change of the number of nuclei over time is proportional only to the number of nuclei.
These long time periods are computed by measuring the ratio of daughter to parent substance in a rock and inferring an age based on this ratio.
This age is computed under the assumption that the parent substance (say, uranium) gradually decays to the daughter substance (say, lead), so the higher the ratio of lead to uranium, the older the rock must be.
Most scientists today believe that life has existed on the earth for billions of years.