Yes, gravitational waves do travel at the speed of light (c) in a vacuum. According to Einstein's theory of general relativity, gravitational waves propagate through spacetime at the same speed as electromagnetic waves.
When gravitational waves pass through matter, such as Earth or the Sun, they can still be detected, although the detection process becomes more challenging. Gravitational waves interact with matter, causing a slight distortion or stretching of spacetime as they pass through. However, the effect on matter is extremely small, making it difficult to detect without sophisticated instruments.
To detect gravitational waves, scientists employ highly sensitive detectors known as interferometers. These devices work by measuring the minute changes in the relative lengths of two perpendicular arms caused by passing gravitational waves.
When a gravitational wave passes through an interferometer, it induces tiny changes in the lengths of the arms, altering the interference pattern of the light that passes through them. By precisely measuring these changes, scientists can infer the presence and properties of the gravitational waves.
While matter can introduce noise and complicate the detection process, interferometers are designed to minimize these effects as much as possible. They are typically operated in vacuum chambers to reduce interference from air molecules, and careful shielding is employed to isolate the detectors from other sources of vibrations and disturbances.
Additionally, the properties of gravitational waves, such as their frequency and waveform, allow scientists to distinguish them from other sources of noise and background signals. By comparing data from multiple detectors and using sophisticated signal processing techniques, gravitational waves can be identified and separated from other sources of noise and interference.
In summary, gravitational waves do travel at the speed of light in a vacuum, and they can be detected even when they pass through matter. Specialized detectors and careful analysis techniques are employed to isolate and identify the extremely faint signals of gravitational waves amidst the background noise and interference.