Bors found his throat going dry. This, of course, was what he'd desperately been denying to himself. It was the fundamental reason for a total lack of hope. The history of warfare is the history of rivalry between attack and defense. In the matter of missiles in space, there was a stalemate. One missile fired in attack could always be destroyed by another fired in defense. It was an arithmetic balance. But it meant that three ships could always destroy two, and four ships three. In the space-fight ahead, there would be at least ten Mekinese ships to every one from Kandar. The sally of Kandar's fleet would not be a rush into battle, but an advance into annihilation. "What we need," said Bors desperately, "is a means to compute courses for our missiles so they'll hit, and that the enemy can't counter-compute—so that his missiles can't compute how to change course in order to cancel ours out."
He was astonished as the words left his mouth. This was what was needed, of course. But then he realized that it couldn't be done.
Logan blew a smoke-ring.
"Mechanical computers," he said, "have limits. They're designed to calculate a trajectory with constant acceleration or no acceleration. But that's all."
Bors frowned. "What else could there be?"
"Changing acceleration," said Logan condescendingly. "A mechanical computer can't compute that. But I can."
Bors continued to frown. One part of his mind assured him that the statement that mechanical computers could not calculate trajectories of missiles with changing acceleration was incorrect. But the rest of his mind tried to imagine such a trajectory. He couldn't. In practice, men do not have to handle the results of variable acceleration as cumulative effects.
"I think," said Bors carefully, "that if you can do that—"
Logan blew a smoke-ring more perfect than any that had gone before.
"I'll calculate some tables," he said modestly. "You can use them on your computer-results. Then if you arrange your missiles to change their acceleration as they go, the Mekinese missiles can't intercept them."