Top Highlights

• Newton had tried to explain the reason why things fall and the planets turn. He had imagined the existence of a “force” that draws all material bodies toward one another and called it “the force of gravity.” How this force was exerted between things distant from each other, without there being anything between them, was unknown—and
• But a few years before the birth of Einstein two great British physicists, Michael Faraday and James Maxwell, had added a key ingredient to Newton’s cold world: the electromagnetic field. This field is a real entity that, diffused everywhere, carries radio waves, fills space, can vibrate and oscillate like the surface of a lake, and “transports” th...
• the gravitational field is not diffused through space; the gravitational field is that space itself. This is the idea of the general theory of relativity. Newton’s “space,” through which things move, and the “gravitational field” are one and the same thing.
• The sun bends space around itself, and Earth does not turn around it because of a mysterious force but because it is racing directly in a space that inclines, like a marble that rolls in a funnel. There are no mysterious forces generated at the center of the funnel; it is the curved nature of the walls that causes the marble to roll. Planets circle...
• The result of Riemann’s thesis was that the properties of a curved space are captured by a particular mathematical object, which we know today as Riemann’s curvature and indicate with the letter R. Einstein wrote an equation that says that R is equivalent to the energy of matter. That is to say: space curves where there is matter.