“Not very much,” said the expendable. “The aliens immediately attempted to seize control of the ship’s computers, remotely. The mice were able to resist their reprogramming, which was feeble and unsophisticated compared to the one they will use near Earth several hundred thousand years from now. Then the Noxon of that ship attached to our paths and jumped back to our time, when the aliens are not able to project their computing prowess this far into space.”

“Narrow escape,” said Wheaton.

“It was a very good thing that we had the mice with us,” said Noxon.

“Thank you,” said the alpha mouse. “We’re glad to reward you for refraining from crushing my head.”

“I never wanted to do it,” said Noxon to the mouse.

“Talking to the mice?” asked Wheaton.

“I wonder,” said Ram, “if our presence here, now, accelerated the aliens’ development of the ability to make remote assaults on human computing systems. Having seen us enter their space . . .”

Wheaton agreed. “Why, it might be that our presence is what led them to attack Earth!”

“No,” said Noxon. “They attacked long before we ever showed up here.”

“We’re here now, and that’s hundreds of millennia before the attack,” said Wheaton.

“Prepare for your head to hurt again,” said the expendable.

“Let me guess,” said Wheaton. “‘Before’ doesn’t always mean ‘before.’”

“The calendar and the clock keep a single line of time,” said Noxon. “But with us, causality jumps all over the place. We’re here before the invasion, by the calendar, but we’re here after the invasion, by the causal chain. Their invasion is what caused us to come, so by cause-and-effect, the invasion was first.”

“I can’t even make my little joke,” said Wheaton, “because the expendable already said it.”

“I anticipated your humor?” asked the expendable.

“You stepped on my joke,” said Wheaton. “Clever, but not polite.”

“You’d already said the joke,” said Ram, “so it wasn’t going to be funny this time. Whereas the expendable stepping on it, that was funny.”

“Amusing, anyway,” said the alpha mouse.

“The mice don’t think any of this is all that funny,” Noxon reported.

“Oh, the women are laughing uproariously,” said the alpha. “I’m the one who isn’t hysterical about it.”

Noxon could see that the female mice were busy at various tasks throughout the ship, and not one of them showed any sign of paying much attention to what they were doing.

“What are you doing to the ship?” asked Noxon.

Noxon could see Ram stiffen a little—he must know Noxon was talking to the mice, and so he feared that the mice might be doing something dangerous and irrevocable.

“We’re making the same alterations to this ship that our counter­parts made to the backward-moving ship,” said the alpha. “So we can jump the fold without making nineteen forward ­copies and one backward one.”

“Are we planning to jump again?” asked Noxon.