Were Online Critics Too Harsh With Interstellar's Science?

Physicist Kip Thorne addresses critiques of movie's plot elements.
Galaxy M81

Galaxy M81 (shown) has a supermassive black hole at its center, comparable in size to the black hole Gargantua in “Interstellar,” which bases its plot elements on real science.

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Ben P. Stein, Contributor

(Inside Science) -- As the movie "Interstellar" prepared to launch into its wide theatrical release last weekend, numerous advance reviews sharply criticized many of the science elements in the movie, from a planet's close proximity to a black hole, to the improbability of a wormhole in our solar system.

As someone who also saw a preview screening, and had no major problems with the movie, I was taken aback by the criticism. Why the harsh reviews? Were they fair?

After reading "The Science of Interstellar," the companion book to the movie, and corresponding with physicist Kip Thorne, the movie's chief science consultant, I believe that the science criticisms were premature.

Thorne wrote to me, "Much of the science underpinning what you see in the movie is far from obvious, until one reads my book."

I believe he is right. Thorne -- and a wide range of crew members from the screenwriters and the director to the visual effects team -- clearly applied extensive thought to all of the science that shows up in the movie, and called upon others in a wide range of disciplines to help make sure everything in the movie had at least a basis in accurate science.

Were the scientific criticisms unfair? I think so, in that the reviewers were not aware of Thorne's full vision.  But to be fair to the reviewers, they couldn't have known all of the movie's scientific underpinnings without reading the book, which came out on November 7, the day the movie was widely released.

"I have no bones to pick with the critics who misinterpreted the science on the first weekend when the existence of my book was not well known. That's perfectly understandable," Thorne wrote to Inside Science in an email. But he hopes the critics will read his book and let their audiences know about any misinterpretations that they have made.

I think many factors actually contributed to why the science elements in "Interstellar" were criticized more harshly than any other sci-fi movies in recent memory.

First, the publicity buildup to "Interstellar" was intense, with advertisements and news articles presenting the movie as a major event with authentic scientific details. And it was a Christopher Nolan movie. Even Nolan himself has said, in a Daily Beast interview, "My films are always held to a weirdly high standard for those issues that isn't applied to everybody else's films—which I’m fine with."

Instead of being a personal thing, it's more likely because Nolan tends to create worlds with interesting rules and internal logic.We often can't help but to think about them. As my Inside Science colleague Chris Gorski has suggested, it's an "uncanny valley" effect--Nolan's worlds seem so real but they are often near the balance point between feeling completely authentic and shockingly fake.

And while other movies with sci-fi elements are sparing in their details (for example, the 2000 film "Frequency" had a minimalistic description of its time-time travel mechanism), "Interstellar" presents a rich smorgasbord of ideas to feast upon, in areas from physics to biology and engineering. These ideas inevitably stimulated the minds of many moviegoers, and naturally begged answers to many science questions, beyond the basic storyline itself. If the film had less science, would the scientific critics have left the film less frustrated, and more satisfied? Would we want that?

Even more factors are at play. On the Internet there is a mad rush to be first, hence the movie reviews being posted as soon as possible after preview screenings. There is of course a strong incentive to say something original, smart and distinctive. So some people went on a limb with their claims that some of the science was wrong—before they had the opportunity to read "The Science of Interstellar," which came out on the same day  as the film's wide theatrical release. This raises another question--should a movie fully stand on its own, in a single viewing, or are supplementary materials such as books acceptable to make it fully satisfying to more people in the audience?

I trusted the science in the movie from the start because I knew Thorne's reputation as a careful and respected physicist, who, among other things, was a longtime professor at the California Institute of Technology. Heck, even the late Carl Sagan consulted him about wormholes when he was working on his novel "Contact." Maybe it was knowledge of Thorne's credentials that brought astrophysicist Neil deGrasse Tyson to the movie's quick defense in interviews such as in the Daily Beast and on his Twitter feed.

However, I too wrestled with some of the scientific elements in the movie. But in each instance, Thorne addressed them in a way that I found satisfactory, either in his book or in our correspondence.

In his book, Thorne describes two guidelines that govern the science in "Interstellar":

"1. Nothing in the film will violate firmly established laws of physics, or our firmly established knowledge of the universe.

2. Speculations (often wild) about ill-understood physical laws and the universe will spring from real science, from ideas that at least some 'respectable' scientists regard as possible."

Each of the book's subsections, addressing topics from wormholes to the widespread death of crops on Earth, receives one of three classifications: "true," in which the science is based on established physical laws, "educated guess" and "speculation."

I'll explain a few of the movie’s science elements that raised questions in my own mind.

There is a blight--a disease afflicting plants-- that wipes out virtually all of the crops on Earth. With my own limited knowledge of biology, I had thought that blights only affected specific species. But as Thorne pointed out in the book, individual factors such as algae blooms can broadly damage ecosystems, and as his biologist colleague Jared Leadbetter mentioned to him, there are "generalist blights" that can affect many species. In his Physics Today review, my colleague Paul Guinnessy wrote, "…it is extremely unlikely that a single disease could wipe out the whole of humanity." As it turns out, Thorne and his biologist colleagues agree this is highly improbable, though possible. Would this scenario seemed more believable if someone in the movie acknowledged the global blight was a freakish occurrence?

Thorne responded that Nolan's purpose was not to describe the science.

"His goal was to make a great film, and adding words to make the science more clear is not generally compatible with that goal - and not in keeping with his very successful style; he benefits from leaving things somewhat mysterious."

In his initial review, astronomer and science writer Phil Plait protested the placement of a planet near Gargantua, the big black hole in the movie. He wrote, "the minimum stable orbit around a black hole must be at least three times the size of the black hole itself."

In the Guardian, astrophysicist Roberto Trotta wrote, "There is simply no planet that can have this kind of gravity and if you tried to land on the surface, it would be so strong it would crush you."

However, as Thorne pointed out (and Plait later realized) the conditions are different around a spinning black hole, such as Gargantua. And Thorne considers the black hole’s tidal forces in the book, and creates a scenario in which the planet near the black hole may have a squashed shape, but not at a point of crushing the planet or its inhabitants.  

Trotta protested further about the conditions on the planet and its proximity to the black hole. "[If] you were to find yourself in this region, you are as likely to die from the radiation from the disc, which is very hot and emitting gamma rays, as much as from the gravitational pull." This seemed to make sense to me, so I asked Thorne about it. Once again, he quoted chapter and verse from his book.

"Gargantua's disk is anemic and at low temperature -- about the temperature of the sun," he wrote. "It's in a very quiescent state. In such a state, its X-ray emission is modest enough that the crew might survive."

Then there is the wormhole in the movie, found in our very own solar system, next to Saturn. It enables the crew of the spaceship Endurance to travel to a far-flung galaxy containing potentially habitable planets they are about to investigate. My screengoing companion Charles Misner, a physicist who collaborated with Thorne on the 1973 textbook "Gravitation" (which is still in print), wondered how the wormhole's mouth could be big enough to let the spacecraft through, without exerting such a strong gravitational pull that it would disrupt our entire solar system. Thorne responded:

"Yes, others have raised that question.  If wormholes can exist at all (and I doubt they can), I am extremely skeptical that they can occur naturally. They have to be designed and constructed by a highly advanced civilization… so in designing the wormhole, Oliver James [chief scientist of the Double Negative visual effects team] and I took the liberty of assuming [an advanced civilization] could adjust its gravitational pull independently of its circumference."

So the filmmakers left the details of creating the wormhole to the advanced civilization, a clever touch, I thought, to handle a speculative plot element based on physics that we are only beginning to understand.

As Thorne makes clear, the filmmakers tuned some of the science in "Interstellar" for the sake of storytelling and a mass audience, but only as much as necessary. In designing the wormhole for the movie, Thorne and the Double Negative team made several versions, with variations in their length, their width, and their mouths' flare, which distorts light from objects behind it. For the view of the wormhole from the outside, Christopher Nolan chose a very short one with modest flare, as that looked nicest. But for the trip through the wormhole he chose a longer one, so the trip wouldn't be too quick.

As Plait made clear, he ultimately had a problem with the storytelling in the movie. With all the scientific concepts on display, and many stretched to their logical limits, I think it was harder for the movie to suspend the disbelief of people who know about these topics.

There is one thing that everyone seems to agree upon--this film was ambitious in its use of real science. It likely introduced many moviegoers to lots of concepts for the first time. There is talk of a sequel. Perhaps this first experience with "Interstellar" will better prepare us for a second one. 

Author Bio & Story Archive

Ben P. Stein is a former director of Inside Science and currently the managing editor in the public affairs office at National Institute of Standards and Technology.