Spacetime and Gravity Albert Einstein (1879 – 1955) Swiss/American physicist

Einstein ’ s Second Revolution Gravity is the primary topic of the general theory of relativity. What is the equivalence principle? What is spacetime? Isaac Newton saw gravity as a mysterious “force.” Einstein theorized that the “force” of gravity arises from distortions of space (or spacetime) itself! spacetime…the 4-dimensional combination of space & time that forms the very fabric of the Universe

Matter Distorts Spacetime Matter distorts spacetime like weights on a taut rubber sheet. The greater the mass, the greater the distortion of spacetime.

Warping of space and time

The Equivalence Principle  For Einstein intuition -- all motion should be relative his equivalence principle: The effects of gravity are exactly equivalent to the effects of acceleration.

Weak equivalence principle In a small region of space, the physical effects of a gravitational field as perceived by an observer are indistinguishable from the physical effects reported by another observer accelerating at a constant rate in the absence of a gravitational field. (A. Zee, p. 18)

Working with: Time Lines in SpaceTime Participation points