Glen Anderson Rebka Jr. (September 19, 1931, Cincinnati – January 13, 2015, Laramie) was an American physicist.
In addition to his academic career he did much work as an experimental elementary-particle physicist at Los Alamos National Laboratory.
In 1960 Robert Pound carried out together with his assistant Glen Rebka an experiment, the Pound–Rebka experiment, using the Mössbauer effect to measure the gravitational redshift of the radiation from a gamma source in the gravitation field of planet Earth.
[2][3] Pound and Rebka used at Harvard University the Jefferson tower, which is only 22.6 meters tall.
Pound and Rebka received in 1965 the Eddington medal of the Royal Astronomical Society.