Light travels at a constant speed of 300,000 km/s regardless of the medium, meaning it cannot be accelerated by moving the medium itself. In scenarios involving a moving spaceship and a laser, observers on the spaceship would see the laser hit a target before those observing from a stationary position, due to the shorter distance the light travels. While the speed of light in a vacuum is always greater than in any medium, the speed of light can be affected by the flow of a transparent medium, as demonstrated in historical experiments. The discussion emphasizes that while there may be potential for improvement in information transmission through optical cables, current technology does not allow for faster-than-light communication. Overall, the conversation highlights fundamental principles of light propagation and the limitations of our current understanding.