Viscount Ilya Romanovich Prigogine (/ p r ɪ ˈ ɡ oʊ ʒ iː n / ; Russian : Илья́ Рома́нович Приго́жин ; 25 January [ O.S. 12 January] 1917 – 28 May 2003) was a Belgian physical chemist of Russian-Jewish origin, noted for his work on dissipative structures, complex systems, and irreversibility.