Although Einstein’s “Zur Elektrodynamik bewegter Körper” (“On the Electrodynamics of Moving Bodies”), known later as his Special Theory of Relativity, and his “Die Grundlage der allgemeinen Relativitätstheorie” (“The Foundation of the General Theory of Relativity”) were published in Berlin in the Annalen der Physik in 1905 and 1916, respectively, his key assumptions about the effects of gravitation on light were not definitively confirmed until the harrowing solar eclipse expeditions led by Arthur Eddington in 1919. With this photographic evidence, Einstein’s theories on relativity, including its implications for a space-time continuum, became popular across the world.