What if things could turn out differently? How the multiverse got into our heads and didn’t let go

“Let’s do things differently this time.”

Those are the first words you hear at the beginning of this month’s “Spider-Man: Across the Spider-Verse,” an otherworldly meditation on multiple realities and how our lives might unfold. The message is clear from the get-go: We have choices. Things could be malleable. You are you, sure. But wait — you might also be you and you and you.

The world is a stressful, sometimes lonely place — and more so at a moment when “It wasn’t supposed to be this way” has become a not-uncommon mantra.

But what if things could turn out another way? What if, somewhere, they had? Enter the realm of the multiverse and alternate realities, one of the most glorified canvases in popular culture’s recent years — and a repository for the ache and longing of living in an era of uncertainty.

Alternate universes are everywhere these days, as the long-delayed opening weekend of “The Flash” attests with its regret-streaked, history-changing storyline (and its multiple variations of Batman). There is a deep hunger, it seems, for exploring possibilities — for seeing what might have been if just one thing had unfolded differently.

“The cultural assumption used to be that the world we live in is the way it is, and that’s the only way it could be,” says Douglas Wolk, who read 27,000 Marvel comics from across the decades for his book, “All of the Marvels.”

“What has happened in culture,” Wolk says, “is that people are saying, ‘Well, no. This consensus reality is not how things have to be.’”

The multiverse has a rich history — or histories

The notion of exploring life’s twists and turns through alternate timelines has been around for a while, albeit in varying guises.

“It’s a Wonderful Life,” the quintessential Christmas movie from 1946, sent the affable George Bailey tumbling into a timeline where he’d never been born to reveal his true impact. “You’ve been given a great gift, George — a chance to see what the world would be like without you,” he’s told by his wannabe guardian angel, Clarence.

In the decades since, that notion has accelerated — a rise in stories that consider events both fictional and real, extrapolating different choices.

What if the South had won the Civil War (“CSA: The Confederate States of America”)? What if Germany and Japan had won World War II ( “The Man in the High Castle” )? What if John F. Kennedy hadn’t been assassinated ( “11/22/63” )? What if the Soviets had beaten the Americans to the moon (“For All Mankind”)? What if 9/11 had played out very differently (“The Mirage”)?

Fictional worlds are more malleable, though, and can yield more content. So it is that imaginary characters — particularly beloved ones with established stories — are toyed with in books, TV shows and movies that airlift them out of one life and into another. It’s a concept that cuts across genres, from rom-com (1998’s “Sliding Doors,” where missing a train splits a young woman’s life into diverging paths) to near-musical (2019’s “Yesterday,” where a budding musician tumbles into a universe where the Beatles never existed).

You have the reality where Spider-Man never married Mary Jane Watson (Marvel Comics’ “Brand New Day”); the universe where one variant of Doctor Strange has gone insane ( “Doctor Strange and the Multiverse of Madness” ); the universe where a Ben Affleck Batman never existed but the Michael Keaton Batman stuck around and got old ( “The Flash,” which we’re not spoiling since this was in the trailers).

And you have the “mirror universe” of “Star Trek,” whose dark and aggressive Terran Empire reveals the baser instincts of beloved characters. Not to mention the recent spate of “Trek” movies, which unfold in yet another reality, splintered when an aging Spock went back in time.

“It’s a way to explore a problem that’s never actually happened in the main story,” sums up Nic Lemire, 13, a California teenager who co-hosts an occasional podcast called “Marvel Mondays” with his mother, former Associated Press film critic Christy Lemire.

One crowning example of multiverse success: Last year’s “Everything Everywhere All at Once,” which showed all the different lives that Michelle Yeoh’s main character might have lived — with the point being that across the multiverse, her family remains a family. It won seven Academy Awards, including best picture.

Whatever the subject matter, these works are united by one theme: There are always possibilities, for better and for worse, and exploring them is entertaining, enlightening and escapist. That’s no small thing in a post-COVID world.