Isotope dating meteorites

The only problem is that we only know the number of daughter atoms now present, and some of those may have been present prior to the start of our clock.

The reason for this is that Rb has become distributed unequally through the Earth over time.

Although we now recognize lots of problems with that calculation, the age of 25 my was accepted by most physicists, but considered too short by most geologists.

The  isotopes will decay into a stable isotope over time.At the  next half-life there will be 25% of the radioactive isotope and 75%  of the stable isotope.Note the strong peak at 4.56 Ga, the conventional age of our solar system and Earth.Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed.The method compares the abundance of a naturally occurring radioactive isotope within the material to the abundance of its decay products, which form at a known constant rate of decay.