December 2: The General Theory of Relativity

Albert Einstein published his General Theory of Relativity on this date in 1916. The theory incorporated gravity into Einstein’s new relativistic portrait of the universe and held that the forces of acceleration and gravity are equivalent. The theory provided a description of gravity as a property of space and time (spacetime) and established the concept of the curvature of spacetime, which includes the shifting of the passage of time by gravity. The theory also implied the existence of black holes, resulting from the collapse of gigantic stars into tiny volumes of enormous mass with such gravitational pull that nothing, not even light, can escape. Einstein’s theory was confirmed within three years by a scientific expedition that observed the deflection of starlight by the Sun during a total solar eclipse. This brought him worldwide fame and, three years later, the Nobel Prize — for a different discovery altogether (about the motion of molecules). For a reasonably accessible explanation of relativity, click here.

“I sometimes ask myself how it came about that I was the one to develop the theory of Relativity. The reason, I think, is that a normal adult stops thinking about problems of space and time. These are things which he has thought about as a child. But my intellectual development was retarded, as a result of which I began to wonder about space and time only when I had already grown up.” —Albert Einstein