Gregory Margulis: "On the early history of expanders" The notion of an expander was introduced in early nineteen seventies by M.S.Pinsker in his work on the complexity of a concentrator. In recent decades the theory of expanders attracted a lot of attention and became a rather big industry. I will talk only about the development of this theory until approximately 1987-88. The opinions expressed in this video do not necessarily reflect the views of the Heidelberg Laureate Forum Foundation or any other person or associated institution involved in the making and distribution of the video.