Ylem was a term used by the physicist who was a developer of the theory credited to whom?
Ylem: Ylem is a term that was used by George Gamow, his student Ralph Alpher, and their associates in the late 1940s for a hypothetical original substance or condensed state of matter, which became subatomic particles and elements as we understand them today. George Gamow: George Gamow (March 4 [O.S. February 20] 1904 August 19, 1968), born Georgiy Antonovich Gamov (Russian: Гео́ргий Анто́нович Га́мов ; ] ), was a theoretical physicist and cosmologist. George Gamow:  He was an early advocate and developer of Lemaître's Big Bang theory.
Lemaître