Einstein’s Theory of Relativity, particularly General Relativity, replaced Newton’s concept of gravity when dealing with very massive objects or extremely fast-moving bodies, where Newtonian physics no longer gives accurate results.
Newtonian Gravity: A Good Approximation
- Newton described gravity as a force between two objects with mass.
- His laws work well for most everyday situations, like predicting the motion of planets or falling apples.
Why Relativity Was Needed
- In extreme environments—such as near black holes, neutron stars, or objects moving close to the speed of light—Newton’s laws fail to make accurate predictions.
- For example, Newton couldn’t explain the anomalous orbit of Mercury or the way light bends around stars.
What Relativity Says
- In General Relativity, gravity is not a force but a curvature of spacetime caused by mass and energy.
- Massive objects warp the fabric of space and time, and this curvature tells other objects how to move.
- Special Relativity handles high-speed motion and shows that time and space are not absolute.
Key Outcomes
- GPS satellites must account for relativistic time dilation to function correctly.
- The bending of light around massive objects (gravitational lensing) is explained only by relativity.
- It laid the foundation for modern cosmology, black hole physics, and gravitational wave astronomy.