▁at ▁Brown ▁was ▁concerned ▁mainly ▁with ▁the ▁effects ▁on ▁diffusion ▁of ▁temperature ▁grad ients , ▁and ▁produced ▁the ▁On s ager ▁reci pro cal ▁relations , ▁a ▁set ▁of ▁equations ▁published ▁in ▁ 1 9 2 9 ▁and , ▁in ▁an ▁expanded ▁form , ▁in ▁ 1 9 3 1 , ▁in ▁statistical ▁mechan ics ▁whose ▁importance ▁went ▁un recogn ized ▁for ▁many ▁years . ▁However , ▁their ▁value ▁became ▁apparent ▁during ▁the ▁dec ades ▁following ▁World ▁War ▁II , ▁and ▁by ▁ 1 9 6 8 ▁they ▁were ▁considered ▁important ▁enough ▁to ▁gain ▁On s ager ▁that ▁year ' s ▁Nobel ▁Prize ▁in ▁Chem istry . ▁ ▁In ▁ 1 9 3 3 , ▁just ▁before ▁taking ▁up ▁the ▁position ▁at ▁Y ale , ▁On s ager ▁tra ve led ▁to ▁Austria ▁to ▁visit ▁electro chem ist ▁Hans ▁Fal ken hagen . ▁He ▁met ▁Fal ken hagen ' s ▁sister - in - law , ▁Mar gre the ▁Ar led ter . ▁They ▁were ▁married ▁on ▁September ▁ 7 , ▁ 1 9 3 3 , ▁and ▁had ▁three ▁sons ▁and ▁a ▁daughter . ▁ ▁Y ale ▁University ▁At ▁Y ale , ▁an ▁embar rass ing ▁situation ▁occurred : ▁he ▁had ▁been ▁h ired ▁as ▁a ▁post do ctor al ▁fellow , ▁but ▁it ▁was ▁discovered ▁that ▁he ▁had ▁never ▁received ▁a ▁Ph . D . ▁While ▁he ▁had ▁submitted ▁an ▁outline ▁of ▁his ▁work ▁in ▁reci pro cal ▁relations ▁to ▁the ▁Norwegian ▁Institute ▁of ▁Technology , ▁they ▁had ▁decided ▁it ▁was