Thomas G. Barnes (August 14, 1911 – October 23, 2001) was an American creationist, who argued in support of his religious belief in a young earth by making the faulty scientific claims that the Earth's magnetic field was consistently decaying.

[1] At the time that Barnes joined the Creation Research Society (CRS) in the early 1960s, he was the head of the Schellenger Research Laboratories at Texas Western College (now University of Texas at El Paso), where he was completing a textbook on electricity and magnetism,[2] and on whose faculty he served from 1938 until he retired in 1981.

[3] Barnes headed one of the first projects of the CRS, to create a creationist high school biology text.

[6][7] Some creationists have used Barnes' argument as evidence for a young earth, less than 10,000 years as suggested by the Bible.

[8] His critics have challenged this concept, claiming that Barnes failed to take experimental uncertainties into account and used an obsolete model of the interior of the earth.