A wikipedia article does not pretend to be proof. It is a summary. For proof you would need to look at the, y'know, evidence. The decay rates of the isotopes in

A wikipedia article does not pretend to be proof. It is a summary. For proof you would need to look at the, y'know, evidence. The decay rates of the isotopes involved are known exactly. It is hard to find anything more certain than timelines revealed by radioactive decay.