Not Gandalf

But you’d be forgiven for thinking so.

It is Alexander Grothendieck (1928-2014), who was a famous mathematician in the area of algebraic geometry. Born in Berlin, his father was Alexander “Sascha” Schapiro (aka Sascha Tanaroff), an anarchist and descendent of bourgeois Hasids from Novozybkov, Russia, near the modern-day borders with Belarus and Ukraine. Grothendieck’s mother was Johanna “Hanka” Grothenieck, also an anarchist and a descendant of middle-class German Protestants from Hamburg. 

Grothendieck survived the Second World War and entered academia as a mathematician, making significant contributions in the area of algebraic geometry. He eventually became convinced that mathematics was immoral, and descended into a madness of religious passion. One presumes that the photograph above is from this later period. 

Via Cliff Pickover on Twitter

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