David Christian is by training a historian of Russia and the Soviet Union, but since the 1980s he has become interested in world history on very large scales. He has written on the social and material history of the 19th-century Russian peasantry, in particular on aspects of diet and the role of alcohol. In 1989, he began teaching courses on “Big History,” surveying the past on the largest possible scales, including those of biology and astronomy. His book Maps of Time: An Introduction to Big History has been called “the single-best introduction to science and history from the Big Bang to the 21st Century.” He is a member of the Australian Academy of the Humanities. Over the next few years, he will also be working with the support of Bill Gates to create an online course in “Big History” for high school students.