When I first met the idea that light from an object that was moving away from us at superluminal speed would never reach us, it seemed quite reasonable. However, I seem to have developed a problem arising from the fact that light must always be observed as travelling at c, irrespective of any relative movement between emitter and receiver. It goes something like this.

A distant object is moving away, relative to Earth, at superluminal speed. At a given point (say 15 billion l y away, which we will call “point A”) it emits a photon. This photon should reach Earth 15 billion years later.

Assume the emitting object is receding (relative to Earth) at 1.5c. One year later it is at point B, which is 16.5 l y from Earth. There it emits another photon, which should reach Earth after 16.5 years; ie, 1.5 years after the arrival of the photon emitted at point A.

Whatever the speed of recession of the emitting object, any light emitted must, from the viewpoint of Earth, be approaching Earth at c, so it must eventually arrive.

I accept that there must be something wrong with this reasoning, but at the moment I can’t see what it is.

There never was nothing.