ABSTRACT
It has been pointed out that, if we can imagine observers moving away from the Earth at speeds comparable to that of light, some curious time effects would appear. It they moved at exactly the speed of light, let us say, on Christmas Day, any Earth light signals would remain the same so that they would, so to speak, stay in Christmas Day. But if they moved faster than the speed of light (a most unlikely event), the time would appear to be reversed for them, because they would overtake the signals sent out by Christmas Eve and then by the day before Christmas Eve, so that Earth time would appear to be running backwards. Speeds faster than that of light can be imagined, but are not likely to be achieved, except in thought. But if thought moves, what is its speed?
