In a real starbuster engagement, even if the novae were occuring only weeks apart, we would see the novae centuries apart here on earth due to lightspeed delay. As a rule of thumb, to see the explosions over a span of a few decades, the warring worlds would have to be just a few light years apart, probably members of a cluster. The Aquila novae are scattered over a much larger area in two dimensions,, so they are likely to be equally scattered in the third dimension.

Its related to the same effect that you get when you see film of a target miles away blowing up, but you hear the explosion immediately, with no time lag. Most film footage of battle scenes
has had the sound dubbed in later.

When I first read Clarke’s speculation I thought of an interstellar war scenario myself, I had a copy of Norton’s and I too had noticed the large number of nova symbols in that part of the sky.

This effect is an unavoidable result of the speed of light, but it can be used to help understand some phenomena. For example, if we see any astronomical object varying (in spectra or light output), the time span of the variation provides us with an upper limit to its size. For example, a millisecond pulsar must be an object no larger than a 300 km across. the distance light can travel in 1/1000 of a second. No physical disturbance can move across an object faster than light, so knowing the frequency of an oscillation gives us an upper limit to the size of what is oscillating.

If we see two supernovae, on the near and far edges of the Andromeda Galaxy ocurring simultaneously, we can say with perfect confidence they are physically unconnected, they MUST be coincidental. Because of the size of Andromeda, the two supernovae must have occured a hundred thousand years apart in time, so that their light could arrive here at the same time. Its not possible one could have had anything to do with the other.