No, gravitational waves do not move at different speeds through different media like electromagnetic radiation does. Gravitational waves are not affected by the medium through which they propagate.
Electromagnetic radiation, such as light, can be influenced by the properties of the medium it travels through. For example, when light passes from one medium to another (e.g., from air to water or from air to glass), it can experience a change in speed due to the refractive index of the medium. This phenomenon is responsible for effects such as the bending of light when it passes through a lens or the dispersion of light into different colors when passing through a prism.
In contrast, gravitational waves are not electromagnetic in nature, and they do not interact with matter in the same way as electromagnetic waves. Gravitational waves are disturbances in the fabric of spacetime itself, caused by the acceleration or movement of massive objects. They can propagate through a vacuum, such as the empty space between celestial bodies, without being significantly affected by intervening matter or media.
Therefore, gravitational waves do not experience changes in speed as they travel through different media or encounter different environments. They move at the speed of light in a vacuum, which is a constant value of approximately 299,792,458 meters per second.