Gravitons are hypothetical particles that are proposed in the framework of quantum gravity theories to mediate the gravitational force. In these theories, gravitons are considered the quanta or particles associated with gravitational waves, just as photons are the quanta of electromagnetic waves.
General relativity, on the other hand, is a classical theory of gravity formulated by Albert Einstein. It describes gravity as the curvature of spacetime caused by the distribution of mass and energy. In general relativity, gravity is not treated as a force mediated by particles, but rather as the geometry of spacetime itself.
The compatibility between gravitons and general relativity arises from the concept of "quantizing gravity." Although general relativity is a classical theory, it is believed to emerge from a more fundamental quantum theory of gravity that includes gravitons. However, a complete and consistent theory of quantum gravity that reconciles general relativity with quantum mechanics is currently an active area of research, and there is no definitive experimental evidence for the existence of gravitons at present.
The challenge in reconciling general relativity and gravitons lies in their different descriptions of gravity. General relativity describes gravity in terms of continuous spacetime curvature, while gravitons imply a quantized particle nature of the gravitational interaction. Reconciling these two frameworks requires developing a quantum theory of gravity that can reproduce the predictions of general relativity in the classical limit while incorporating the particle-like behavior of gravitons at the quantum level.
Various approaches, such as string theory, loop quantum gravity, and others, have been proposed as potential candidates for a theory of quantum gravity. These approaches attempt to provide a consistent framework where gravitons and general relativity can coexist. However, the development of a complete and experimentally verified theory of quantum gravity is still an ongoing and challenging task in theoretical physics.