Theorists generally identify two historical periods in which time–space compression occurred; the period from the mid-19th century to the beginnings of the First World War, and the end of the 20th century. In both of these time periods, according to Jon May and Nigel Thrift, "there occurred a radical restructuring in the nature and experience of both time and space... both periods saw a significant acceleration in the pace of life concomitant with a dissolution or collapse of traditional spatial co-ordinates".