They cry and cry, GPS,GPS. But how about that satellite : the moon ? Is time dilation measured actually ? Where is the starting point of reckoning ? From view point of an observer on the moon's surface, is there any difference between time dilation of Singapore (near the equator) and the North Pole (From view point of an observer on the earth, there is no difference) ??
And to two observer (at the above two points on the earth), how about the watch on the moon ? Even as an armchair theory, it seems not to stand up.