Consider the diagram of superluminal motion in Figure 24-11 of Universe, 11th ed. Suppose the motion of the blob of material continued on in a straight line at 5/6c for an additional 5 years to position C. Viewed from Earth, the speed of the blob would then appear to be:
A) 5/6c.
B) 11/12c.
C) 1.5c.
D) incalculable. In this case the light from the final position C would arrive at Earth before the light from the initial position A.

Question

Quizplus · Accepted Answer

Superluminal motion is an apparent phenomenon where objects seem to move faster than the speed of light due to the geometry of their motion and the finite speed of light. When an object moves at a significant fraction of the speed of light and part of its motion is directed towards an observer, the time intervals between the observations of different positions of the object are shortened. This can make the object appear to move faster than light, even though its actual speed is less than the speed of light. In the scenario described, continuing the motion at 5/6c for an additional 5 years in a straight line, and considering the effects of superluminal motion, the apparent speed can indeed seem to be faster than light, hence 1.5c is a plausible apparent speed due to these relativistic effects.

Consider the Diagram of Superluminal Motion in Figure 24-11 of Universe