Emil John (Jan) Konopinski (December 25, 1911 in Michigan City, Indiana – May 26, 1990 in Bloomington, Indiana) was an American nuclear scientist[1] of Polish descent.

[3][4] During WW II Konopinski collaborated with Enrico Fermi on the first nuclear reactor at the University of Chicago.

He also joined the Manhattan Project to develop the first nuclear weapon (atomic bomb).

[5] He, together with C. Marvin and Edward Teller, showed that a thermonuclear explosion would not ignite the atmosphere and thereby destroy the earth.

[6] An Atomic Energy Commission consultant from 1946 to 1968, he wrote a book entitled The Theory of Beta Radioactivity.