Light is considered as a wave because it exhibits wave-like properties, such as interference, diffraction, and polarization. These properties can be explained by the wave nature of light, which is characterized by its ability to propagate through a medium or vacuum in the form of oscillating electric and magnetic fields.
The wave nature of light was established through various experimental observations, such as the double-slit experiment, which demonstrated the interference pattern created by light passing through two slits. Additionally, the wave model of light successfully explained phenomena like the refraction and reflection of light, as well as the phenomenon of interference in thin films.
On the other hand, gravitational waves are not considered as particles but rather as waves in the fabric of spacetime itself. Gravitational waves are ripples or disturbances in the curvature of spacetime, predicted by Einstein's theory of general relativity. These waves are generated by the acceleration or movement of massive objects, such as merging black holes or neutron stars.
Gravitational waves have been detected and confirmed by experiments such as the Laser Interferometer Gravitational-Wave Observatory (LIGO). They exhibit wave-like behavior, including characteristics like frequency, amplitude, and propagation speed. The detection of gravitational waves has provided evidence for the wave nature of gravity, as predicted by Einstein's theory.
It's important to note that both light and gravitational waves can exhibit dual nature, behaving both as waves and particles under certain circumstances. This duality is described by quantum mechanics, which suggests that all particles, including photons (particles of light), can sometimes exhibit wave-like behavior, and vice versa. This phenomenon is known as wave-particle duality. However, it's essential to differentiate between the wave nature of light and the wave-like behavior of gravitational waves, as they arise from different physical phenomena.