Gravitational waves are currently understood as ripples in the fabric of spacetime caused by the acceleration of massive objects. However, the concept of wave-particle duality is typically associated with quantum mechanics, where particles like photons can exhibit both wave-like and particle-like behavior.
In the realm of general relativity, which describes gravity, the wave-particle duality concept is not applicable in the same way as in quantum mechanics. Gravitational waves are described as a purely wave-like phenomenon in the framework of general relativity.
That said, it is important to note that there is ongoing research to reconcile general relativity with quantum mechanics, which is one of the major challenges in theoretical physics. The field of quantum gravity seeks to develop a theory that can unify these two fundamental theories of nature.
As for testing the wave-particle duality of gravitational waves, it would require the development of a theory that incorporates both quantum mechanics and gravity. At present, such a theory does not exist. Researchers are actively exploring ideas and frameworks like string theory, loop quantum gravity, and others in an attempt to reconcile these two fundamental descriptions of the universe. Once a theory of quantum gravity is established, it may provide insights into the nature of gravitational waves at a more fundamental level. However, until such a theory is developed, it is not possible to test the wave-particle duality of gravitational waves directly.