Using circular logic -- assuming that decay rates remained constant despite necessarily changing physical characteristics as time approached the origin -- Old Earth proponents insist that the Earth is 4.5 billion years old based on an assumption of constancy in [[Potassium-argon dating|Potassium-argon (K:Ar) decay rates]] and other radiometric methods.<ref>Peck, 2000, p.376.</ref> | Using circular logic -- assuming that decay rates remained constant despite necessarily changing physical characteristics as time approached the origin -- Old Earth proponents insist that the Earth is 4.5 billion years old based on an assumption of constancy in [[Potassium-argon dating|Potassium-argon (K:Ar) decay rates]] and other radiometric methods.<ref>Peck, 2000, p.376.</ref> |