“I've got a question,” Liz said.

“What?” her mother and father asked together.

“What happens if something now makes the home timeline split into two alternates?” Liz said. “They'd both have Crosstime Traffic in them. Which one would be the real home timeline?”

Mom and Dad looked at each other. They walked on for several steps without answering. At last, her father said, “If there are no other questions, class is dismissed.”

“Dad!” Liz said reproachfully.

“We're just historians. We can't deal with questions like that,” her mother said. “You need to talk to the chronophysicists. If anybody can tell you, they're the ones.”

“Talk to them at a convention, after they've got a few drinks under their belts,” Dad added. “If you get 'em when they're in the lab, they'll look wise and tell you things like that can't happen. I hope they're right. Everybody does.”

“How will we find out?” Liz asked.

“The same way people usually do, I bet,” her father answered. “The hard way.”

“Come on! Come on! Get moving!” Sergeant Chuck booted Dan in the seat of the pants. He didn't kick him hard enough to hurt, but it was plenty hard enough to wake him.

Chuck went on shouting and booting other soldiers awake. Dan yawned and stretched and looked around. The sun hadn't risen yet, but it would soon. It was already bright enough to see colors. Only a handful of the brightest stars still shone, and they faded out as he watched.

He pulled a square of hardtack and some smoked sausage from his pack. Some soldiers crumbled up their hardtack and fried it in bacon grease. He just crunched on his. You needed good teeth to do that. He had good teeth, and knew how lucky he was to have them. Wounded soldiers got ether before surgeons went to work on them. Ordinary people with toothaches? You needed to be rich to get knocked out before a dentist pulled a tooth that was driving you nuts.