Final answer:
If the speed of light were not constant, then the speed at which we receive light from a star would vary depending on the star's B. position and velocity. This question challenges the principle of the speed of light's constancy, central to modern physics and theoretical constructs like black holes derived from it.
Step-by-step explanation:
If the speed of light were not absolute, the speed at which light from a star in a binary system came towards the Earth would depend on the star's position and velocity. The concept that the speed of light is constant regardless of the motion of the source or the observer is a cornerstone of Einstein's theory of relativity. This question involves understanding that if the universal constancy of the speed of light were not maintained, the motion of the source of light (in this case, the star) would affect how we perceive the speed of that light.
In the history of physics, the speed of light had been measured by Ole Rømer using the orbital period of Jupiter's moon Io, recognizing the role of the relative positions of celestial bodies. Moreover, the works of Michell and Laplace considered the implications of light having a finite speed, resulting in the theoretical concept of an object from which light could not escape, now known as a black hole.
Relativity tells us that an astronaut moving relative to Earth will experience effects such as time dilation and length contraction. For instance, if the astronaut is moving at a significant fraction of the speed of light, his clocks appear normal to himself but the rate of Earth-bound clocks seems sped up; his ship remains the same size in his frame of reference but appears shortened to an Earth-bound observer, and the distance between stars along his path seems shorter.