Putting the science in science-fiction can be trickier than it seems, just ask Mike Cahill and Brit Marling, co-writers of the Sloan Prize-winning film Another Earth. The film follows Rhoda Williams, a young woman who killed a mother and child in a drunk-driving accident, which derails her plans to attend MIT and study astrophysics. Sentenced to four years in prison, she befriends John, the husband and father of the people she killed after her release.
The plot of Another Earth could end with that small synopsis. It is still a dramatic situation, perfect for a small-scale budget film. But Cahill and Marling had other plans. On the night of the drunk-driving accident, another Earth appears in the sky. Earth 2, as it is called in the film, is filled with duplicates of everyone on the original Earth, including a Rhoda who might not have killed a mother and child. When a millionaire entrepreneur offers the winner of an essay contest a seat on the first civilian spaceflight to Earth 2, Rhoda sees her chance to meet her other self.
Explaining the Science
The truth is that Another Earth has very little science explanation in the film. Cahill and Marling, who also directed and starred in the film respectively, did consult with astrophysicist Richard Berenson to ensure the science of the film came from a place of accuracy. But after including exposition on the why and how of Earth 2 in the original screenplay, Cahill cut the explanations out of the film, explaining “it felt a little expositional. It felt like a science lesson."
Still, the plot of the film is inspired by real science. The multiverse, the idea of infinite universes with infinite outcomes, got Cahill and Marling’s brain churning. What if one of the other earths in one of the infinite universes could travel to ours? What if you could meet your other self? “The idea would be that another version of our [Earth] somehow went through a wormhole and somehow ended up on the opposite side of our sun. And that's called superior conjunction. We don't know. We don't have good photographic evidence of what lies behind our sun... We took that notion that the multiverse somehow jacked into our world — they collided — which takes a leap of faith, that's not scientifically probable. And it ended up behind our sun,” said Cahill.
Is It Enough?
The film does take leaps and bounds with science. Earth 2 violates laws of physics, planetary orbit and gravitational pull (another scientific explanation Cahill dropped from the original screenplay) but Another Earth is not a documentary, it is fiction. But according to physicist (and member of the Sloan panel at Sundance) Sean Carroll, Another Earth is “an excellent example of a certain kind of fruitful interaction between science and cinema.”
That fruitful interaction is an exchange, a give and take of fact and fiction, storytelling and accuracy. Another Earth does not need to be judged by if it has “enough science,” but grounding the story in scientific concepts opens the characters and plot to a new host of intricacies. For Cahill, the other Earth serves as a metaphor throughout the story, adding a certain depth to the film. Without Earth 2, Rhoda is another character, wishing for a different outcome, rather than a character that can see the other outcome directly in front of her, up in the sky. As Marling explains it, “Sometimes in science fiction you can get closer to the truth than if you had followed all the rules.”