Aorist rods were created during a galactic energy crisis, by a man who one day realized that the one place that never seemed to use up all of its energy was the past. He created a way to mine that energy that very night and the form that this energy came in was aorist rods. Using them caused the past to become dull and unremarkable.
Nobody wanted to get rid of them, because it provided a clean and unending amount of energy. There were people who said that the past should remain untarnished, but they didn't. There were even those who claimed that draining the past of its energy was also draining the present. The only reason they got rid of them was because they realized that the present was being drained by the people in the future that were doing the exact same thing, so they had to get rid of them and the secret to their creation forever.
If aorist rods are to explode, there is a large chance that they will cause the history in that area to become less interesting and it can even change the past if the explosion is powerful enough.
The starship Billion Year Bunker had aorist rods within that were scheduled for jettisoning into a black hole, before the ship crashed.