1 6 . ▁ ▁He ▁then ▁moved ▁to ▁Columbia ▁University ▁as ▁a ▁gradu ate ▁student , ▁obtain ing ▁a ▁Ph D ▁in ▁mathematics ▁in ▁ 1 9 2 0 . ▁ ▁Douglas ▁was ▁one ▁of ▁two ▁w inners ▁of ▁the ▁first ▁Field s ▁Med als , ▁awarded ▁in ▁ 1 9 3 6 . ▁He ▁was ▁hon ored ▁for ▁solving , ▁in ▁ 1 9 3 0 , ▁the ▁problem ▁of ▁Pl ate au , ▁which ▁asks ▁whether ▁a ▁minimal ▁surface ▁exists ▁for ▁a ▁given ▁boundary . ▁The ▁problem , ▁open ▁since ▁ 1 7 6 0 ▁when ▁Lag range ▁raised ▁it , ▁is ▁part ▁of ▁the ▁calculus ▁of ▁variations ▁and ▁is ▁also ▁known ▁as ▁the ▁soap ▁b ubble ▁problem . ▁Douglas ▁also ▁made ▁significant ▁contributions ▁to ▁the ▁inverse ▁problem ▁of ▁the ▁calculus ▁of ▁variations . ▁The ▁American ▁Mathemat ical ▁Society ▁awarded ▁him ▁the ▁B ô cher ▁Memorial ▁Prize ▁in ▁ 1 9 4 3 . ▁ ▁Douglas ▁later ▁became ▁a ▁full ▁professor ▁at ▁the ▁City ▁College ▁of ▁New ▁York ▁( CCN Y ), ▁where ▁he ▁taught ▁until ▁his ▁death . ▁At ▁the ▁time ▁C CN Y ▁only ▁offered ▁under grad uate ▁degrees ▁and ▁Professor ▁Douglas ▁taught ▁the ▁advanced ▁calculus ▁course . ▁Soph om ores ▁( and ▁fresh men ▁with ▁advanced ▁pla cement ) ▁were ▁privile ged ▁to ▁get ▁their ▁introduction ▁to ▁real ▁analysis ▁from ▁a ▁Field s ▁medal ist . ▁ ▁Selected ▁papers ▁ ▁See ▁also ▁Pet r – D oug las – Ne umann ▁theorem ▁ ▁Notes ▁ ▁References ▁Biography ▁in