General relativity
Theory · 1907 to 1915, Germany · Physics, stage 2: Map the theories
General relativity is Einstein's theory of gravity, completed in 1915 after eight years of work. Its starting point is the observation that someone in free fall feels no gravity, so the effects of gravity and of acceleration cannot be told apart locally. Einstein turned this into the claim that gravity is not a force at all but the curvature of spacetime produced by mass and energy, with objects following the straightest available paths through that curved geometry. The theory predicted the bending of starlight measured in 1919, the precession of Mercury's orbit, black holes, and gravitational waves, which were detected directly in 2015. It supersedes Newtonian gravity while reproducing it wherever gravity is weak.
What it claims
- Being in free fall is locally indistinguishable from being far from any gravitating body.
- Mass and energy curve spacetime.
- What is called gravity is objects moving along the straightest paths in curved spacetime.
- Clocks run more slowly where gravity is stronger.
Key ideas
People
Sources
- General relativity English Wikipedia
- Early Philosophical Interpretations of General Relativity Stanford Encyclopedia of Philosophy
- General relativity Britannica
