Gravitario

Gravitario is a term sometimes used in some languages or popular literature to denote the hypothetical quantum of the gravitational field, equivalent to what physicists usually call the graviton. In this sense, the gravitario would be a massless, spin-2 boson that mediates the gravitational interaction in a quantum theory of gravity. The concept arises from attempts to quantize the gravitational field as with other gauge bosons in the Standard Model.

In linearized gravity around Minkowski spacetime, small perturbations of the metric can be treated as a field, whose quanta would be these gravitarios. They would couple to the energy-momentum tensor and would be long-range due to being massless. Because gravity is extremely weak, gravitarios would interact only with very small coupling constants and would be difficult to detect directly; they would be extremely challenging to produce in colliders and to observe in detectors.

Status: No experimental evidence confirms gravitarios; gravitational waves, detected by LIGO/Virgo, are classical perturbations of spacetime, not quanta; a full quantum theory of gravity is still lacking. Searches for quantum-gravity effects place indirect constraints, but a gravitar has not been observed.

In practice, the standard term used in physics is gravitón; "gravitario" is more common in some languages as an informal synonym or in fictional contexts. The concept remains a theoretical construct within approaches to quantum gravity, including string theory and loop quantum gravity, where gravitons or graviton-like excitations are predicted in appropriate limits.