ian ▁ ▁known ▁for ▁his ▁work ▁in ▁quantum ▁elect rod ynam ics , ▁solid - state ▁physics , ▁astronom y ▁and ▁nuclear ▁engineering . ▁He ▁was ▁professor ▁emer it us ▁in ▁the ▁Institute ▁for ▁Advanced ▁Study ▁in ▁Pr inc eton , ▁a ▁member ▁of ▁the ▁Board ▁of ▁Vis itors ▁of ▁R al ston ▁College ▁and ▁a ▁member ▁of ▁the ▁Board ▁of ▁Sp ons ors ▁of ▁the ▁Bul letin ▁of ▁the ▁At omic ▁Scient ists . ▁ ▁D ys on ▁origin ated ▁several ▁concepts ▁that ▁bear ▁his ▁name , ▁such ▁as ▁D ys on ' s ▁transform , ▁a ▁fundamental ▁technique ▁in ▁add itive ▁number ▁theory , ▁which ▁he ▁developed ▁as ▁part ▁of ▁his ▁proof ▁of ▁Mann ' s ▁theorem ; ▁the ▁D ys on ▁tree , ▁a ▁hypoth et ical ▁gen et ically - engine ered ▁plant ▁capable ▁of ▁growing ▁in ▁a ▁com et ; ▁the ▁D ys on ▁series , ▁a ▁perturb ative ▁series ▁where ▁each ▁term ▁is ▁represented ▁by ▁Fe yn man ▁diag rams ; ▁the ▁D ys on ▁sphere , ▁a ▁thought ▁experiment ▁that ▁attempts ▁to ▁explain ▁how ▁a ▁space - f aring ▁civil ization ▁would ▁meet ▁its ▁energy ▁requirements ▁with ▁a ▁hypoth et ical ▁meg astr ucture ▁that ▁completely ▁en comp ass es ▁a ▁star ▁and ▁capt ures ▁a ▁large ▁percentage ▁of ▁its ▁power ▁output ; ▁and ▁D ys on ' s ▁et ernal ▁intelligence , ▁a ▁means ▁by ▁which ▁an ▁imm ort al ▁society ▁of ▁intellig ent ▁be ings ▁in ▁an ▁open ▁universe ▁could ▁escape ▁the ▁prospect ▁of