The Chicago Cubs are in the World Series for the first time in decades. The team’s losing streak is legendary: it hasn’t won the title since 1908, and last made it to the Series in 1945. It’s a drought that has become so ingrained in culture that it’s held up as an enduring yardstick for the idea that there are just some things will always stay the same, even far into the future.

The losing streak is supposedly due to a curse placed on the team in 1945, which author Jim Butcher adapts in his 2011 Dresden Files short story "Curses." In it, a pair of mythological Welsh figures level the curse on the Cubs when they’re not permitted to watch the game.

That’s not the only time that the Cubs has figured into speculative fiction. The team has popped up in a handful of books and movies over the years. The losing streak has become such a predictable thing that it’s assumed that it will never, ever be broken, which makes it the perfect continuity benchmark for science fiction. How can you tell which world or timeline is correct? Check and see if the Cubs have won. If they have, you’re probably in the wrong place.

One of the most notable examples of the Cubs’ losing streak was also the most optimistic for their prospects: in Back to the Future II, Marty McFly notices a holographic headline that announces that the Cubs have swept the World Series in 2015.

Another example comes from Andy Weir’s bestselling novel The Martian, which also picks up the Cubs as a reference point. In the novel, Mark Watney is stranded on Mars, keeping a diary of entries as he fights to survive. His entry for his eleventh day on the planet is short:

I wonder how the Cubs are doing.

When asked about the line, Weir noted that he wasn’t a Cubs fan, but that he included the reference to the team because "I just thought that would be just the thing to make Mark’s pathetic situation even more pathetic." Not only is Watney stranded, but his favorite team can’t even make the World Series.

The dig also made it into one of the film adaptation’s promotional videos, where the Chicago-born Mark Watney asks the Cubs to hold off on winning a world title until he’s back:

Given that The Martian takes place in 2035, it’s clear that Weir isn’t exactly holding his breathe for a Cubs win anytime in the near future, and recently poked some fun at the situation in a Facebook post:

According to the marketing material for "The Martian", today is Mark Watney's 22nd birthday. And his favorite team, the Cubs, advanced to the NLCS last night. Good times for Mark... for now... Posted by Andy Weir on Wednesday, October 12, 2016

Some authors are even more cynical about the prospects of a Cubs win. John Scalzi works the Cubs into his novel The Human Division, where the team becomes a pivotal plot point. In the fifth chapter, "Tales from the Clarke," one character, Wilson, begins to suspect that the passengers they just picked up are, he takes his suspicions to his superiors, outlining the team’s centuries-long losing streak.

"It means," Wilson said, "that there’s no possible way a Cubs fan who has been on Earth anytime in the last two years would fail to tell any baseball fan that the Cubs won the Series. And when I identified myself as a Cards fan, Tiege’s first reaction should have been to rub the Cubbies victory in my face. It’s simply impossible.

Later in the chapter, the team and the situation is used to unveil the duplicity of their passengers:

"The Cubs won the Series two years ago, Marlon," Wilson said. "What?" Tiege said. "Swept the Yankees in four. Final game of the Series, the Cubs hurler pitched a perfect game. Cubs won a hundred and one games on the way to the playoffs. The Cubbies are world champions, Marlon. Just thought you should know." Coloma watched Marlon Tiege’s face and noted that the man’s physiognomy was not well suited to showing two emotions at once: utter joy at the news about the Cubs, and complete dismay that he’d been caught in a lie.

Scalzi noted in an interview in 2013 that the team has an obligation to keep up their losing streak:

"We need to have a team that has the courage and fortitude not to win, to be the people who are an example of striving and reaching and going and failing, but still continuing to do it."

These handful of examples appear to each come from the same place: that the idea that the Cubs can win is so unrealistic that it’s like science fiction. Up to this point, the team’s misfortunes are the longest-running in professional baseball, making it easy to assume that this streak will never end.

Update: Well, the Cubs won the series! It looks like this means that science fiction will have to move to another standard for gauging reality: the Cleveland Indians.