sentences:  When NASA tested the theory in space shuttle experiments they discovered the theory didn't work as they at first expected and realised the way engineers had been using it needed to be reconsidered.Wagner officially retired in 1966 but from 1967 to 1977 was a Scientific Member of the Max Planck Institute in Göttingen, continuing to contribute to publications.Many modern inventions based on solid state technology and Semiconductor fabrication, used in devices such as solar energy conversion have been developed with the aid of Wagner's theories.