itt gen stein , ▁who ▁res igned ▁his ▁professor ship ▁in ▁ 1 9 4 7 . ▁ ▁In ▁ 1 9 4 7 ▁D ys on ▁published ▁two ▁papers ▁in ▁number ▁theory . ▁Fri ends ▁and ▁colle agues ▁described ▁him ▁as ▁sh y ▁and ▁self - eff acing , ▁with ▁a ▁contr arian ▁stre ak ▁that ▁his ▁friends ▁find ▁ref res hing ▁but ▁his ▁intellectual ▁oppon ents ▁find ▁ex as per ating . ▁" I ▁have ▁the ▁sense ▁that ▁when ▁cons ensus ▁is ▁forming ▁like ▁ice ▁hard ening ▁on ▁a ▁lake , ▁D ys on ▁will ▁do ▁his ▁best ▁to ▁chip ▁at ▁the ▁ice ", ▁Steven ▁Wein berg ▁said ▁of ▁him . ▁His ▁friend ▁the ▁ne uro log ist ▁and ▁author ▁Oliver ▁S acks ▁said : ▁" A ▁favour ite ▁word ▁of ▁Fre eman ' s ▁about ▁doing ▁science ▁and ▁being ▁cre ative ▁is ▁the ▁word ▁' sub vers ive '. ▁He ▁feels ▁it ' s ▁rather ▁important ▁not ▁only ▁to ▁be ▁not ▁orth odox , ▁but ▁to ▁be ▁sub vers ive , ▁and ▁he ' s ▁done ▁that ▁all ▁his ▁life ." ▁ ▁Career ▁in ▁the ▁United ▁States ▁ ▁On ▁G . ▁I . ▁Taylor ' s ▁advice ▁and ▁recommendation , ▁D ys on ▁moved ▁to ▁the ▁United ▁States ▁in ▁ 1 9 4 7 ▁as ▁a ▁Commonwealth ▁Fellow ▁to ▁ear n ▁a ▁physics ▁doctor ate ▁with ▁Hans ▁Bet he ▁at ▁Corn ell ▁University ▁( 1 9 4 7 – 1 9 4 8 ). ▁There ▁he ▁made ▁the ▁acquaint ance