Gravitonin

Gravitonin is a hypothetical elementary particle described in some speculative theories as the quantum mediator of gravitational interactions. In mainstream physics the proposed quantum of gravity is the graviton, a massless spin-2 boson; gravitonin remains informal and is not part of established theory. The term appears in various models and science-fiction contexts to denote a different carrier of gravity, often with properties that differ from the conventional graviton.

Proposed properties vary by model. Some versions posit a massive boson, which would mediate a short-range modification of gravity, while others consider a scalar or vector particle with extremely weak coupling to ordinary matter. The exact spin, mass, and coupling structure are model-dependent. In many constructions, gravitonin is intended to address puzzles such as the behavior of gravity at cosmological scales or the unification of gravity with quantum field theory, by introducing new symmetries, extra dimensions, or non-standard kinetic terms.

Theoretical status: gravitonin is speculative and not supported by direct experimental evidence. It is distinguished from the gravitino, the supersymmetric partner of the graviton, which is a fermion with spin 3/2. If a gravitonin exists, its effects would generally appear as deviations from Newtonian gravity or as dispersive propagation of gravitational signals, but current observations—ranging from solar-system tests to gravitational-wave measurements—place stringent limits on any additional gravitational mediator with observable couplings.

Because it is not experimentally established, gravitonin remains a niche concept and a topic of speculative research rather than a settled element of physics.