As a high-speed spaceship flies passt you, it fires strobe light that sends out a pulse of light in all directions. An observer aboard the spaceship measures a spherical wave front that spreads away from the spaceship with the same speed c in all directions. (a) what is the shape of the wave front that you measure? (i) spherical; (ii) ellipsoidal, with the longest exis of the ellipsoid along the direction of the spaceship's motion; (iii) ellipsoidal, with the shortest exis of the ellipsoid along the direction of the spaceship's motion; (iv) not enough information is given to decide. (b) Is the wave front centered on the spaceship?

1 answer

(a) (i) spherical.
(b) Yes, the wave front is centered on the spaceship as it is spreading out uniformly in all directions from the source.