Final answer:
According to Einstein's theory of relativity, a beam of light sent from one observer to another will approach at the speed of light, regardless of their relative velocity.
Step-by-step explanation:
According to Einstein's theory of relativity, the speed of light in a vacuum is constant and independent of the relative motion of the source and observer. This means that for any relative velocity v between two observers, a beam of light sent from one to the other will approach at speed c, which is the speed of light.
It does not matter if the observers are moving at different speeds; the speed of light remains the same. This conclusion is supported by Maxwell's equations, which describe the behavior of electromagnetic waves like light.