What Does Einstein’s General Relativity Actually Mean?
Mathematically, it’s a monster, but we can understand it in plain English.
Although Einstein is a legendary figure in science for a large number of reasons — E = mc², the photoelectric effect, and the notion that the speed of light is a constant for everyone — his most enduring discovery is also the least understood: his theory of gravitation, General Relativity. Before Einstein, we thought of gravitation in Newtonian terms: that everything in the Universe that has a mass instantaneously attracts every other mass, dependent on the value of their masses, the gravitational constant, and the square of the distance between them. But Einstein’s conception was entirely different, based on the idea that space and time were unified into a fabric: spacetime, and that the curvature of spacetime told not only matter, but energy too, how to move within it.
This fundamental idea — that matter and energy tells spacetime how to curve, and that curved spacetime, in turn, tells matter and energy how to move — represented a revolutionary new view of the universe. Put forth in 1915 by Einstein and validated four years later during a total solar eclipse — when the bending of starlight coming from light sources behind the sun agreed with Einstein’s predictions and not Newton’s — general relativity…
