“It will help. It's bound to,” her mother answered.

“It may take a while, though,” her father added. “I envy ancient historians. There's only so much for them to know. It's not like that when you get up into the twentieth century. You're drowning in data. It does seem plain that the breakpoint has to do with the Vietnam War, though.”

“We already knew that,” Liz said. “Or we were pretty sure, anyhow.”

Her father nodded. “It was always a good bet, since the big war started while the Vietnam War was going strong. But it still isn't obvious whether the U.S. escalation here scared the Russians enough to make them start throwing rockets, or whether the United States threw them first when we didn't like what Russia and China were doing.”

“Whoever shot first, an awful lot of people on both sides ended up dead.” Liz eyed this sorry version of the UCLA campus. “And there's been nothing but trouble ever since.”

“Nobody's going to tell you you're wrong, hon,” her father said. “At that, they got off lucky here. They got bombed back to the Middle Ages, but they didn't get bombed back to the Stone Age.”

“They didn't all get killed, either,” Mom said. “That happened in some alternates.”

Liz nodded. People really could be stupid. Just in case the home timeline didn't have enough examples of that, the alternates offered even more. People in the home timeline hadn't been stupid some ways. They hadn't tried blowing one another off the map with H-bombs, for instance. They were proud of that, and relieved about it, too.

Seeing what other people, people much too much like them, had done in different alternates should have made them prouder of escaping-and also more relieved. To some degree, it did. But only to some degree. Too many people in the home timeline still had axes to grind. Big wars seemed unlikely these days. Terrorist strikes, on the other hand…