He was also active in the Norwegian language conflict (målstriden, språkstriden or sprogstriden) and was leader of the Riksmål Society in Norway 1969 to 1974.
[citation needed] Lydersen grew up in the coastal village Narestø at Flosta in the Aust-Agder county.
He returned to NTH in 1948, where he taught refrigeration engineering, and completed the degree of Doctor Technicae (dr.techn.)
Lydersen and Hougen became good friends, and started a long lasting cooperation between the chemical engineering departments in Trondheim and Madison.
During his stay in the US, Lydersen was also employed at Miller Brewing Company in Milwaukee for a shorter period.
While in the United States, Lydersen developed a method for the estimation of critical properties for temperature (Tc), pressure (Pc) and volume (Vc), based on already published data.
Determination of physical data became a central research activity when he returned to NTH, now also based on his own measurements.