What should I ask Stephen Kotkin?

Kotkin’s most prominent book project is his three-volume biography of Joseph Stalin: The first two volumes have been published as Stalin: Paradoxes of Power, 1878–1928 (2014) and Stalin: Waiting for Hitler, 1929–1941 (2017), and the third volume remains to be published.

Here is more from Wikipedia, of course he is an expert on the Soviet Union and also Russia more generally:

Among scholars of Russia, he is best known for Magnetic Mountain: Stalinism as a Civilization which exposes the realities of everyday life in the Soviet city of Magnitogorsk during the 1930s. In 2001, he published Armageddon Averted, a short history of the fall of the Soviet Union…

He is currently writing a multi-century history of Siberia, focusing on the Ob River Valley.

He is currently at the Hoover Institution.  So what should I ask him?