General Relativity: Gravity as Curved Space-Time
A New Theory of Gravity
Why Special Relativity Was Not Enough
Special relativity handles constant-velocity motion, but real gravity involves acceleration and changing motion. Einstein extended his ideas to create general relativity.
Main Idea
Gravity is not treated as a normal force in general relativity. Instead, mass and energy curve space-time, and objects move along that curved geometry.
The Equivalence Principle
Einstein realized that being in a closed accelerating elevator can feel locally like being in a gravitational field. This leads to the equivalence principle, one of the foundations of general relativity.
Newton vs Einstein
Newtonian view
- Gravity is a force acting at a distance
- Space and time are fixed backgrounds
Einsteinian view
- Gravity is geometry
- Space-time can bend and change
In general relativity, gravity is best described as what?
General relativity explains gravity as curvature of space-time.
Correct answer: A curved space-time geometry
What principle links acceleration and gravity locally?
The equivalence principle is central to general relativity.
Correct answer: equivalence principle
Which idea did Einstein extend beyond special relativity?
General relativity expands the framework to include gravity and acceleration.
Correct answer: Accelerating and gravitational motion
The Big Picture
General relativity says matter tells space-time how to curve, and curved space-time tells matter how to move. This elegant idea changed astronomy and cosmology forever.