Swedish physical chemist whose researches on colloids, biological molecules, and radiochemistry significantly affected both theoretical and applied chemistry. In order to investigate the behavior of very small particles, Svedberg invented the ultracentrifuge, which he also used to study proteins and carbohydrates. His researches on Brownian motion helped to establish the existence of molecules. Svedberg was one of the first to recognize the existence of isotopes. He received the 1926 Nobel Prize for his work on colloidal systems.