Maybe you can tell me how you measure the speed of light in the box to be c? In exactly which direction did it take light exactly .5 seconds to travel from the source to the receiver??? The x direction? How about the y and z directions, at .65 seconds???? There is no place in the box that you can measure the speed of light to be c, period. As a matter of fact, the speed of light in the box depends on which direction you measure it, as I've showed with numbers, that you yourself agree with.