General theory of relativity
theory of general relativity and field equations
General theory of relativity is the generalization of special theory of relativity. It states that laws of physics should be same for all observers whether they are moving at constant speed or accelerating. The distance between two points in spacetime becomes what is called Riemannian metric. Riemannian metric is the generalization of Gauss's first fundamental form to higher dimensional space- 4 dimensional spacetime of relativity for our purpose. Riemannian metric defines what is called metric tensor. Consequently everything becomes generalized in general relativity: straight line becomes geodesics, derivative becomes covariant derivative and many other entities as are required to formulate general relativity.
General theory of relativity has a larger sweep than any other theories that have been developed so far. A certain kind of admixture of geometry and physics had been done in general theory. Geometry which was assumed a constant feature of the world is no more constant according to new theory. Gravity is not a force according to Einstein. To gain further insight about the theory certain abstruse(very complicated) mathematics need to be pursued and understood. There are few fundamental concepts which can be elucidated(explain) in apparently simple way:
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