An interactive diagram illustrating the rubber sheet analogy of spacetime curvature. Learners can place masses of varying sizes on the sheet and observe how the grid distorts and how test particles move along geodesics.
Learn MotionBlack Holes: Physics, Structure, and Theory
Foundations of General Relativity
Curved Spacetime and Geodesics
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So, if gravity isn't a force, what is it? It is the curvature of spacetime. Massive objects like stars warp the fabric of space and time around them. Objects moving under gravity alone are simply following 'geodesics'—the straightest possible lines in this curved geometry. Think of it like airplanes flying great circles on Earth; they think they are going straight, but on the curved surface, their path arcs. Similarly, planets orbit stars because they are following the curves carved into spacetime.
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