What is the Difference Between Einstein and Newton Gravity?

The main differences between Einstein's and Newton's gravity are as follows:

1. Concept of Gravity: Newton envisioned gravity as a tug of war along the line connecting any two objects in the universe, while Einstein envisioned gravity as a bending of space-time by mass.
2. Speed of Gravity: Newton assumed that gravity is felt everywhere in the Universe instantaneously, meaning it travels at infinite speed. In contrast, Einstein incorporated the cosmic speed limit, the speed of light, into his theory, which means that gravity does not travel faster than the speed of light.
3. Source of Gravity: Newton believed that the source of gravity is mass, while Einstein's theory recognizes that the source of gravity is not mass, but energy, one form of which is mass.
4. Equivalence Principle: Einstein's theory is based on the Equivalence Principle, which states that the laws of physics should have the same form in all inertial frames and that all inertial frames are equivalent.
5. Geodesics: In Einstein's theory, free-falling objects follow the shortest path through the curved spacetime, which are called geodesics. This concept is not present in Newton's gravity.

In summary, Newton's gravity is based on the idea of a force acting along the line connecting two objects, with instantaneous action and a source of gravity being mass. Einstein's gravity, on the other hand, is based on the concept of spacetime curvature due to energy, with the speed of light as the limiting speed, and the equivalence principle as its foundation.

Comparative Table: Einstein vs Newton Gravity

Here is a table summarizing the differences between Einstein's and Newton's gravity:

Newton's gravity, as described by his law of universal gravitation, views gravity as a force between objects in space, while Einstein's gravity, described by general relativity, sees gravity as a curvature in a 4-dimensional space-time caused by the presence of mass and energy. Einstein's gravity also introduces the concept of geodesics, which are the shortest path through curved spacetime, and the speed of gravity, which is equal to the speed of light.