Sign up for our Headlines morning newsletter.

The most interesting things on the web, handpicked each day. Sign up for our Headlines morning newsletter.

Science in Fiction

View of Earth from Saturn by NASA's Cassini on July 19, 2013

Do You Believe in Ghosts?

Ignore the critics: Christopher Nolan’s Interstellar is not only a serious, complex comment on space policy, it’s a heartbreaking, philosophical look at the value of time.

Last summer, after interviewing Professor David Kaiser, a theoretical physicist and historian of science at MIT, I switched off my recorder. As I prepared to leave, I decided to venture another question against my better judgment, apologizing in advance that it would probably sound kooky: “Is there any possibility, however remote, that ghosts exist?” Professor Kaiser’s brow wrinkled. Oh no, I said to myself, he probably thinks I’m yanking his chain or playing gotcha somehow. But no, he replies, given the right caveats, he’s willing to accede he doesn’t know for a fact that ghosts are impossible, even though he finds it difficult to conceive the physical logic of such a thing. And incidentally, have I read his book, How the Hippies Saved Physics, which he was called kooky just for writing?

One final outlandish question about time travel and I thank him for his patience, shake his hand, and turn to leave, satisfied that I dared ask an MIT physics professor about the strange thoughts that came to me during a late-night gab, a rainy evening with friends after we’d had several amaretto sours and decided to watch Fabric of the Cosmos, a NOVA special on cosmology. The NOVA feature, which talks about ten-dimensional space and black holes, stirred up some unusual thoughts. What did everyone think, I’d asked: Were ghosts, however unlikely, possible? How about backwards time travel? Which was more unlikely? Which was more (“more”) paradoxical?

Several months later, when I left a theater at 2:00 a.m., technically the day after the opening night of Interstellar, I knew immediately I would need to speak to Professor Kaiser again. The film’s universe had somehow managed to address all of my questions about ghosts and time travel, as though it had been arranged specially to suit my interests. A spooky, kooky coincidence? The story of Interstellar precisely concurred with my philosophical convictions. In its world, backwards time travel is impossible. But ghosts? That’s another thing entirely.

 

Spoiler and also boredom warning: This next passage summarizes key plot points in Interstellar and gives away at least one surprise.

Interstellar tells the story of Cooper (Matthew McConaughey), a NASA pilot who’s been relegated to farming duty following a traumatic crash. In the movie’s not-too-distant future, our world has become Steinbeck meets Huxley, a Brave New Dust Bowl. It’s a place in which:

  1. our crops have succumbed to blight;
  2. our schools sort children into castes by high-stakes testing (sound familiar?); and
  3. our brainwashed teachers tell kids that the moon landings never happened.

The only thing we have left is corn—long, gleeful shots of which anchor the movie’s aesthetic—but it might die soon, too.

Interstellar’s scientific accuracy has become something of a public preoccupation, the kind of thing on which Neil deGrasse Tyson is asked to make pronouncements.

Cooper’s wife is dead. He and his father-in-law (John Lithgow) take care of big-hearted 15-year-old Tom (Timothée Chalamet, later Casey Affleck) and precocious 10-year-old Murph (Mackenzie Foy, later Jessica Chastain, later still Ellen Burstyn). Murph is named after Murphy’s Law, the formulation that “anything that can go wrong, will.” But, as Cooper says, there’s a more scientific way to think of that law, which is usually presented as a joke: “given enough trials, anything that can happen, will.”

It’s a good watchword for a film that entertains some of the wildest possibilities conceived by contemporary physics. The screenplay, which features black holes, neutron stars, and time travel, was written in consultation with Caltech theoretical physicist Kip Thorne, who is credited as an executive producer, and its science—though wacky—is realistic. Thorne even learned something about the behavior of black holes from working with Nolan’s effects team and has academic articles forthcoming about his discoveries.

When a set of lines that mysteriously appear on his floor provide him with its coordinates, Cooper discovers that NASA still exists. The space agency been forced to go underground, defunded by a public convinced we’ve got enough to worry about down here. Cooper—pilot, explorer, engineer—is offered an assignment. He must travel through a wormhole that NASA has discovered near Saturn, seeking habitable worlds to which humanity could flee. There is Plan A, which requires building anti-gravity spacecraft big enough to get everyone off our dying planet, which in turn requires solving the problem of quantum gravity. And there is Plan B, which requires discovering, and possibly terraforming, another planet to create a human colony, leaving us unlucky earthlings behind to the dire fate we’ll eventually meet.

The whole sequence at NASA is a bit of an info dump. It conveys essential information very rapidly: There were previous missions, 12 brave astronauts who journeyed through the wormhole, led by the intrepid Dr. Mann (Matt Damon). We learn that the wormhole itself was placed there by higher-dimensional beings of some kind, an anonymous “They.” And we learn that the wormhole leads to another galaxy in which there are three possible Earth twins, all located near a massive black hole called Gargantua (the rendering of which is utterly stunning). Cooper and his crew—Dr. Brand (Anne Hathaway), Romilly (David Gyasi), and Doyle (Wes Bentley)—must go through the wormhole and check out the various worlds. Their hope is that Dr. Brand’s father, Dr. Brand (Michael Caine), can solve quantum gravity (so Plan A can succeed), but, if that fails, they’ll have to go to Plan B.

For Cooper, going on the journey will mean leaving his children behind, possibly even leaving them for dead. He will have to contend not just with the hostilities of deep space, but with Einsteinian relativity, the slowing of time in a deep gravitational well, such that—up close to the black hole—a few hours of his time will mean several years back on Earth. So, in human terms, even if he succeeds, his kids may well be old or dead before they’ll ever know if their father will come back.

In the powerfully sad last scenes of Act One, Cooper decides to go. He leaves his son Tom and, more significantly, his cherished daughter Murph (parents really do play favorites, it seems). Cooper weeps as he drives away in his pickup. The film plays the sounds of the countdown before it even shows us the rocket. Hans Zimmer’s massive score swells. Then… ignition! Cooper blasts off into the inky blackness, heading to a place lightyears away from the children he loves.

 

Interstellar’s scientific accuracy has become something of a public preoccupation, the kind of thing on which Neil deGrasse Tyson—apparently the Delphic oracle of 2014—is asked to make pronouncements on NPR. Professor Thorne even wrote a book, The Science of Interstellar, which discusses the physics of wormholes, black holes, and intense time dilation due to gravity. I read it in its entirety. But neither the endorsement from Tyson nor Professor Thorne’s involvement with the project dissuaded people from taking pot-shots at the film’s science. For example, physicist Phil Plait, writing for Slate, argued that the film’s gravitational mechanics were wrong. “For the planet to have the huge time dilation claimed in the movie,” he wrote, “it would have to be too close to the black hole to have a stable orbit.”

This assertion proved a bit hasty: As Kip Thorne himself explained in an article that predates Plait’s, the black hole is spinning very rapidly, which changes its gravitational properties. When shown his error, Plait wrote a retraction admitting he hadn’t read Thorne’s book before making his conclusions. And in fact Interstellar makes clear his assumption was incorrect. In an expository sequence, Romilly directly states that the black hole is spinning, calling it a “gentle singularity.”

Despite confessing his error, Plait clung to the notion he’d been correct in his negative assessment of Interstellar, saying he simply didn’t care for the story. “A lot of people have accused me of disliking the movie because I thought the science was bad,” he wrote. “That’s simply incorrect. I disliked the movie because I thought the story wasn’t told well.” But if the science was immaterial in the first place, why did Plait write more than 2,000 words complaining about it?

Everyone seems to need reassurance that the story wasn’t just a portrait of what’s soon to be our reality. So, we witness critics struggling to pin the butterfly down.

For other writers, like the Atlantic’s Noah Gittell, the problem isn’t the physics, it’s the climatology. Gittell argues that Interstellar’s apocalyptic vision is unserious, since it doesn’t push audiences to engage with real scientific issues of climate change. “Nolan has set up a false choice,” he complains. “In the world of Interstellar, mankind can either leave the planet behind, or it can stay here and die. The choices that humans actually have to make regarding climate change and the future of the earth are much more complicated, and are nowhere to be found onscreen.”

However, there’s little reason to think that the film was even supposed to be about climate change. Screenwriter Jonathan Nolan told IGN, “You know, it’s not a message film. I believe we should be good custodians of the Earth… but I also believe that what will most likely wipe us out will be something that has nothing to do with us.” While Interstellar is certainly evocative about the environment, its dystopia—the killer blight that destroys all our crops—is essentially fiction. Kip Thorne’s book confirms this understanding. In other words, it seems Gittell must have mistaken the multiplex for a lecture hall. Even though climate change is a serious issue, Hollywood fiction simply isn’t obligated to deliver feel-good sermons for deserving liberals.

Rather, Interstellar’s dystopia, like all dystopias, reflects and exaggerates certain features of our reality. It’s affecting because it’s scary, not because it preaches the “right” political message. Perhaps there is a need for someone to make A Really Inconvenient Truth: Al Gore Already Done Told You, but that hardly seems like a fair lens through which to assess Interstellar. However righteous the cause, not every movie needs to be propaganda. That lockstep conception of moviemaking is, in fact, pretty dystopian.

At the same time, Interstellar’s status as fiction makes the intensity of the scientific and political debates around it all the more intriguing. Upon watching Nolan’s film, everyone seems to need reassurance that the story wasn’t just a portrait of what’s soon to be our reality. So, we witness critics struggling to pin the butterfly down. But when was the last time a film hit so close to home that it caused people to question their boundaries (and then required them to educate themselves about theoretical physics to understand the reply)? Nolan has blurred the line between art and reality in a way that has made a lot of us uncomfortable. And that’s a very good thing.

 

The thematic heart of Interstellar is not the depiction of relativity or the fable about agricultural blight; it’s the story about love between parent and child. At first blush, this might seem like a simplistic, cheesy theme. How many times has science fiction told us that, what horrors may come, still love conquers all? (Recall the cheesy mass-release endings of Ridley Scott’s Blade Runner and Terry Gilliam’s Brazil, for instance.)

Hokey though it may sound, this rough-worn theme ultimately deepens Interstellar’s politics. While cold calculations and dispassionate science can represent facts objectively, they can’t, by themselves, provide motivation for doing anything. That has to come from the heart, I’m afraid.

Nolan’s heart, it seems, is in outer space. So, if Interstellar has a stance, it’s not about science or climate change; it’s about space policy. His film presents a compelling answer to the question: Why should we care what’s up there? After all, even if the climate is changing, we’ll likely be dead before the worst effects are felt. Well, as Nolan told the Daily Beast, because we love our children and want them to feel safe. For him, it’s an inescapable truth that private psychic struggles structure even our grandest battles, as illustrated in Inception and The Dark Knight trilogy.

Samantha Marquart, an aerospace engineer who worked at Virgin Galactic, now completing a PhD in space policy at George Washington University, seemed excited by Interstellar’s existence, but wasn’t sure it would do much to change public opinion about space exploration. “The public isn’t very informed about the more everyday effects of space-based technologies,” she told me. “We use technologies like our phones’ GPS systems or Google Earth without realizing that they rely on outer space. These technologies wouldn’t exist without the fleet of satellites we’ve launched into orbit, satellites that require regular space missions for maintenance.”

“On short time-scales, we’re stuck here. So we need to find ways to make it less miserable. If exploration isn’t part of the plan anymore, that’s dangerous.”

But what about something more exotic, more terrifying, like the blight depicted in Interstellar, that would force us to seek a new home? “Well, with its current funding profile, NASA couldn’t handle anything disastrous. NASA today is mostly concerned with using space as a way to study Earth in addition to being concerned with space exploration itself. But there are things that could come and destroy us—asteroids, for instance. We’ve just got this thin little band of atmosphere. I wish I was joking, but the smartest thing that happens in the film is sending NASA into hiding.”

Mary Knapp, who worked at NASA’s Jet Propulsion Labs and is now completing a PhD at MIT, where her laboratory is building a spacecraft that will study exoplanets, seemed surprised when I asked if the Interstellar mission was unrealistic. “Well, I’d say that a major goal of my whole field is to find that Earth twin,” she said matter of factly. But was it plausible to believe we’d find such a thing? Shouldn’t we worry about our own planet? “On short time-scales, we’re stuck here. So we need to find ways to make it less miserable than what’s depicted in Interstellar. But turning inward and thinking short-term is not going to solve big problems. We have to seek out novel, out-of-the-box, even crazy solutions. If exploration isn’t part of the plan anymore, that’s dangerous.”

But wasn’t it completely implausible to believe we’d find another home? “The Kepler mission and other exoplanet observations tell us that, on average, every star has at least one planet. The only reason we haven’t found an Earth twin is observational… Whether the atmosphere would be breathable, that’s another question. We have no idea whether there’s photosynthetic life. But I think it’s safe to say that there are Earth-like planets out there.”

Yet the public conversation about the movie centers on nitpicking the physics or worrying whether Nolan’s climate politics are in line with the party.

 

Some further exposition and spoilers ahead.

The movie’s first act is kind of mysterious: Some strange things are going on around Cooper’s farm. His daughter is convinced there’s a ghost in her bedroom. Books and other objects keep falling from her bookshelves. An Indian surveillance drone is sent off course and soars by. Cooper decides to chase it through the cornfields and hijack it. But then his tractors strangely decide to return home, as though heeding a call. And then a pattern of mysterious marks appear on the floor following an intense dust storm.

What’s going on is this: Cooper is sending gravitational signals through spacetime in a crude effort to communicate with his young daughter and past self. In the third act, he elects to launch himself into the black hole—driven by the hope (probably vain, he knows) that it will allow him to rewind time and make it back to Earth to see his children again. Just as he is about to be spaghettified by the intense gravity, he falls into a four-dimensional object called a tesseract.

The tesseract links the black hole with a place in spacetime that is: (space) just behind the bookcase in Murph’s old bedroom and (time) just before Cooper left on his original journey. So, Cooper is offered an extraordinary opportunity; he has a crude way of trying to communicate with his own past. That’s what’s causing all the weird stuff that’s happening at the beginning of the movie. The farm is haunted—in the most literal, scientific way conceivable—by a ghost. Nolan’s concealment and (finally, finally) revealing of this information is, in a word, mind-blowing.

It makes the value of time, and the pain of its loss, clear in human terms.

At first, Cooper thinks the tesseract is hell itself, a prison composed of his most painful memories. He cries useless tears, screams at himself in agony. “Make him stay, Murph!” He types out “S.T.A.Y.,” using the book spines as Morse code. It’s a haunting portrait of the power of regret. But Cooper’s efforts are unavailing. He realizes he cannot alter his own past in the tesseract—that would be paradoxical. The movie delivers this information in a short exchange between Cooper and the lovable robot TARS (the new R2D2 as far as I’m concerned). While he can send signals, he can’t change his own course. So he accepts his fate goes and sends himself the NASA coordinates. All he can do is hope to alter his daughter’s future. So he encodes the quantum data—the key to solving quantum gravity—into the second hand of the watch he gives her when he leaves, hoping that she will someday come back to find it. She has to conquer a scientific puzzle, but the only way to find the answer is to understand her relationship with her father.

For me, these scenes were profound. They made me think not just about the nature of time, but its value, which is more than I can say for most time-travel movies. These scenes recontextualize the film’s space grand opera in small, human, psychological terms. They’re heavy hitting. “Once you’re a parent, you’re the ghost of your children’s future,” Cooper whispers to Murph as he leaves. He has no idea how right he is. The same holds for us: What we do with our time on Earth determines what kind of world our children will inherit. We might affect them in ways we’ll never even be there to see.

 

I will confess I cried during Interstellar, cried multiple times, and I know from looking around the theater that I was not alone. This didn’t change with repeat viewings. In fact, my fourth time seeing the movie was the most intense. Understanding it better—having read Kip Thorne’s book and listened closely to the dialogue—only deepened my sense of its tragedy.

Interstellar’s most heart-stopping scenes—which are made more stunning by the fact that they are physically possible—get us to engage with the idea of losing precious time with those we love in a starkly real way. Through the contortions of relativity, the film is able to frame wild, otherworldly comparisons. In one unforgettable sequence, Cooper and Brand return from a failed mission on a water planet beset by intense tidal waves. Because of the planet’s proximity to the black hole, 23 years of Earth time have elapsed, though it was just a few hours for them. All the while, they’ve been getting messages from their loved ones back on Earth. So, Cooper must sit and watch, helpless, as the children he loves so dearly grow up without him. It’s devastating stuff, and McConaughey nails the scene. He tries to smile, but finds himself sobbing uncontrollably. His son finishes school, falls in love, has a kid. And then, after so much time without hearing from his dad, he concludes his messages are just drifting off into blackness and decides to let his father go. Cooper cries and shakes his head, a mixture of understanding and refusal of acceptance. It’s an emotional doozy. It makes the value of time, and the pain of its loss, clear in human terms.

If you go to Interstellar and don’t feel real, human sadness, sorry, but you may be a cynic. In fact, those words strike me as a good summation of the critical response.

“I’m not sure why everyone is being so hard on it,” said Professor Kaiser. “If scientists are going to bash movies like this, all we’re ever going to get is The Hulk 17.” So why had scientists rushed to criticize a project in which Kip Thorne was involved? It seemed like a curious gambit. “Yes, I agree,” Kaiser said. “To be fair, though, some of the research on spinning black holes on which the film was drawing has really only occurred in the past decade. The articles Kip cites are as recent as 2013. So these developments wouldn’t necessarily be familiar to someone whose education in physics was decades ago.”

So what did he, Kaiser think of the film’s science? “I loved it. It’s thrilling to see Hollywood engaging with important cutting-edge research in physics.” Were there any flaws? “The only thing I thought could have been given more explanation were the ideas of the bulk and higher-dimensional space. There’s a fascinating literature that’s been developing around the brane world and the warping of spacetime. Right now, audiences will have to go to Kip’s book to be clued in.” But of course, from the standpoint of promoting interest in science, that’s probably a good thing.

In the end, Interstellar is a wonderfully scientific film, and a marvel to look at. Like all science fiction, it stretches and bends the rules to suit its narrative needs. And what’s more, it’s a politically complex film that urges us to reflect on the necessity of space exploration not by sloganeering, but by asking us for soul searching and introspection about our love for our children. It suggests that to solve our society’s problems, we have to journey in. Interstellar works hard to get us in touch with a fundamental part of our experience—the passage of time—and it confronts us with this truth: The choices we make determine what kind of ghosts we’ll become.