Robert Vance Gentry was an American young Earth creationist and nuclear physicist, known for his claims that radiohalos provide evidence for a young age of the Earth.

Charles Leroy Ellenberger is perhaps best known as a one-time advocate, but now a critic, of controversial writer Immanuel Velikovsky and his works on catastrophism. He first read Worlds in Collision in 1969. In 1979, he became a contributing editor to the Velikovsky-inspired Kronos journal, and has contributed material to many other publications. In 1980 he was selected by the editor of Astronomy magazine to debate James Oberg on Velikovsky.