Light travels at the same speed, approximately 299,792,458 meters per second (or about 186,282 miles per second), in a vacuum regardless of the medium. This speed is often denoted as the speed of light in a vacuum and is a fundamental constant in physics. In other words, whether light is traveling through air, water, glass, or any other transparent medium, its speed remains constant as long as the medium is not a vacuum. However, when light passes through a different medium, its path may be altered or it may experience other effects such as refraction or dispersion, but its speed remains unchanged.