The best model we have begins with the Big Bang. With all of the rest of creation, a time wave is created as a continuous stream. It might be an anomaly, might be necessary to keep everything else stable, but there it is. Think of it as a thick glob of paint on a sheet of glass. It runs down the glass, when we tilt it, at a slow and steady speed. The edge is where time is now, still running down so long as everything else is expanding, but the paint trail it left is still there. The edge, where we are now, is the sum of that trail. Alter that trail, and you will start a ripple that will run down to catch up with the leading edge. The math is rather esoteric, but the ripple will run at ten times the edge rate primarily because it’s smaller. If it’s a tiny ripple, it may resolve things and die out quickly. A big wave, though—it would change the sum of the world.”

Moosic had a sudden, uneasy thought. “What about others? Would we even know if, say, the Soviets had a project like this? They’re doing fusion research now.”

“No, there’s no way of knowing. Of ever knowing. A time war would be the most frightening thing of all. However, it would still be badly limited in several respects. It would require enormous power. It would require a country insane enough or desperate enough to risk its own lot on a new roll of the dice. And it would certainly involve few participants in any event, participants who would be limited to a small amount of time in any frame to accomplish much at all. The Soviets are our opponents. They are not mad, which is why we are all still here. Neither are the current Germans, Japanese, Chinese, or others capable of such a project. It is only the fear that someone else is doing it that keeps us funded at all, so expensive is this operation. We spend a lot of time trying to convince them that there is military potential, when actually there is not. But we don’t know, of course. And so long as NSA’s very budget is classified, we can continue to get the money. You keep us out of unfriendly hands.”