Chern, Shiing-Shen, 1911–2004, Chinese-American mathematician, b. Kashing (now Jiaxing), China, D.Sc. Hamburg, 1936. While undertaking graduate studies in China (1932–34), Chern developed what became a lifelong interest in differential geometry. Pioneered in the 19th cent. by Carl Friedrich Gauss in his studies of curves and surfaces, differential geometry received little attention among mathematicians until the 1930s and 40s, but Chern transformed this dormant branch of mathematics into a vibrant area of study. Studying the curvature of surfaces in spaces with more than three dimensions, he devised mathematical quantities that he called characteristic classes—now known as Chern classes—that differentiated different types of surfaces. The fields on which he had the greatest impact, global differential geometry and complex algebraic geometry, are fundamental to many areas of mathematics and theoretical physics, and his work at the foundation of gauge theory and string theory, among the most important developments of modern theoretical physics.