Featured as a back-of-page article in the CSABC Quarterly Letter of December 2016

by David Kadylak

Let’s explore is how radiocarbon (carbon-14) is found nearly everywhere. You’ve probably heard of radioactive carbon-14 used as a common dating method. Due to its short half-life, 5,730 years, it can never demonstrate that something is millions of years old. On the other hand, any carbon-14 found in now-dead organic material can only be 200,000 years old at a maximum. Coal and fossil wood, found in layers supposedly hundreds of millions years old, still has ¹⁴C levels well above the limit for detection [D.C. Lowe, Problems associated with the use of coal as a source of ¹⁴C free background material, Radiocarbon, 31 (1989) 117-120] and even after taking possible contamination into effect. In fact, if the whole earth were a clump of carbon-14, there would be absolutely no radiocarbon in less than 1 million years. (See below if you are interested in the calculations.)

Mass of earth: 5.97 x 10²⁷ g

moles of ¹⁴C: (5.97 x 10²⁷ g)/(14 g/mol) = 4.26 x 10²⁶ mol

(1 mol of C = 6.02 x 10²³ C atoms, atomic mass of ¹⁴C = 14 g/mol)

atoms of ¹⁴C: (4.26 x 10²⁶ mol) x (6.02 x 10²³ atoms/mol) = 2.57 x 10⁵⁰

number of halvings to get to 1 atom:

log₂(2.57 x 10⁵⁰) = log(2.57 x 10⁵⁰)/log(2) = 167

years of decay with a half-life of 5,730 years:

167 x 5,730 = 956,910 years < 1,000,000 years