As you may well know by now, I’m a huge fan of the natural sciences. Usually, I use the space allotted to me here to try and explain some interesting bit of science in more simple terms, so that those of us who aren’t as big on the giant formulas and heavy textbooks can still get a glimpse of, say, the realities of time travel. Or, sometimes, I just like to investigate something silly – like coffee. Today, we’re doing something a little different. After all, we’re a magazine for writing, literature, and film, and so I thought I’d take you on a little trip through the science of a recent, well-received Hollywood Sci-Fi blockbuster: Interstellar.
Allow me to first put things into perspective somewhat by giving a brief summary of the movie. In Interstallar, Cooper (an astronaut and engineer by trade), his two children and his father-in-law live in the not-too-distant future in which things have gone pretty sour. Basically, the whole economic system has come crashing down because of food shortages, and now almost everyone works as a farmer, trying to scrape by and survive the onslaught of hunger and natural disasters. Cooper, through what appears to be a freak incident, happens to find what remains of NASA, who are doing what they can to give humankind some kind of future among the stars. And, of course, they need him to come back and become the pilot for their final mission in an effort to save mankind from its total extinction.
I’ll deliver to you first some of the more noteworthy science blunders, after which I’ll move on to the successes, all of which is going to be intertwined with my own bits of personal commentary both on film-critic front as well as otherwise. One important thing to note before we depart: I’m going to assume here that you’ve actually seen the movie. I’ll try to make clear which scene it is that we’re talking about every time, but it’s going to be a lot less interesting for those of you who haven’t seen it yet, in which case: spoiler alert! Go get yourself a copy somewhere and watch it first. It really is quite good, and well worth your time.
Our first dose of science-fail is delivered right in the first this scene: here Cooper and his two kids are in their car, when they suddenly encounter an Indian air force drone. This little miracle of modern tech is able to fly forever due to being outfitted with powerful solar cells, and thus a valuable a resource in such a time of scarcity. So what do they do to get their hands on it? They hack the drone using a special kind of wireless remote control. Wait, what? Now, I’m going to come clean here and say that I’m not an expert on hacking in any way, but this certainly tickled my skepticism. Why would the Indian air force ever build a drone that lets just any old engineer with too much free time and an old router take it over within all of two minutes? I’m letting it slide here on the grounds that Cooper is very, very good at basically everything, but I’m still not entirely buying into this “well screw security! Who would ever hack this little flying wonder?”. Zero points, Chris.
And on to the next fail we go! Here, Cooper’s daughter has left the window open in a dust storm, a frequent happenstance on our pre-apocalyptic Earth, and suddenly Cooper has found the explanation for the “ghost” his daughter has been complaining about for a few days now. You see, books were falling out of her shelf on their own accord – being a man of science, Cooper initially dismissed the thought of there being something weird. In fact, just that morning he told her “you can’t just say ‘it was a ghost’; you’ve got to do your experiments, analyse your results, and base your conclusions on that.” Now, however, he finds himself faced with inexplicable, neat lines of dust on the floor. Then he flips a coin in the air that is strongly drawn onto one of the lines, seemingly confirming his hypothesis, and he whispers very loudly: “It’s gravity!”
There’s only one problem here: how is that the very first thing he came up with? This is not something gravity does – ever. You see, gravity behaves as a spherical field around very heavy things – like planets or black holes. Everything of sufficient mass pulls things towards it with decreasing strength proportional to the distance – if you’re somewhere above the Earth, gravity will pull you down with a certain force, which is determined by how far away you are from the Earth – there’s no difference in gravity depending on which direction you’re facing. It’s a symmetrical force.
As such, gravity has never been observed to manifest as tiny cylinders like this. The only way I can think of to do this would be to put rows of teeny-tiny black holes there, which could in some ways appear to be cylindrical sources of gravity – but that would also produce lots of other effects, like the floor being slowly devoured.
Some sort of magnetism, I’d offer, would have been much more likely to produce line-shaped structures. You could even try and confirm this at home, with some iron dust and a simple magnet you can buy at the DIY store. Strangely, this was mentioned just a few minutes earlier in the film as the possible cause of all the strange events (like compasses failing) that were happening around the farm. But hey, let’s conveniently dismiss that because gravity is much cooler! Worse yet, how is his instant conclusion (by his own reasoning!) any better than his daughter claiming it was a ghost? For tall the testing he’s done, it might as well have been a ghost.
What’s even worse, not only does he just instantly conclude that gravity must be responsible, he then goes on to instantaneously decipher the code and see that it’s coordinates written in binary. But how does he know this? Out of all the millions of possible encodings, why would it just have to be binary? Why not Morse, as Murphy originally thought it was? Why didn’t he spend even a millisecond thinking about alternative possibilities? It’s almost like he knew at this point already that it was future Coop sending that message to his past self – the only problem being that he of course couldn’t know that yet at this point. So many plot holes, you’re starting to hurt my brain, Coop. Sadly, it’s not about to get better soon: we’re moving on to possibly the strangest, most poorly supported bit of “science” in the entire movie. Hold on to your hats folks.
Our third bit of fail deals with the mysterious plant disease, called the Blight, which is killing all the plants the people of Earth need to survive – this is one of the major causes of the collapse of human society. At this point in the movie, Cooper is talking to his mentor and old NASA colleague, a professor who’s spent his life working in science. I’m paraphrasing him here: “Earth has lots of nitrogen. The Blight breathes nitrogen. Therefore, Blight depletes the oxygen.”
Wait, what? So, the Blight apparently needs lots of nitrogen, but then it also depletes all our oxygen? Also, it’s capable of depleting the Earth’s atmosphere of most of its oxygen in just a few decades while it only grows on stuff like corn? Let’s zoom in on this last bit first. According to National Geographic, crops currently take up a surface area the size of South America – that may sound like much, but even if we guess very roughly that could hardly be more than half to one-third of the total amount of plants we have on Earth. Now, let’s be a bit charitable, and say that we’ve got Blight on all of those crops. Would that realistically be enough to deplete oxygen levels to such lows that humans would suffocate within just a few decades? Think about it: the current amount of oxygen is so absurdly immense, and humans can still live in such a wide variety of oxygen levels, that even if they would deplete the oxygen in the air very quickly, it would take thousands, if not millions of years for it to deplete – as is to be expected of a buffer of oxygen that was, after all, built up over hundreds of millions of years!
But what’s even more strange is that they’re making it sound like it’s a kind of bacterium – first of all, because there’s very few other organisms (all of which are plants) that ‘breathe’ nitrogen; second of all because it’s parasitic, which is not something plants typically are. But then again, those species of bacteria that do actually breathe nitrogen are usually either actually damaged by oxygen, or are unable to absorb nitrogen in oxygen-rich environments. I may not be a biologist, but on the surface this sounds like such crude logic I’d really like to find the writer who dreamt this one up. And you know what is the worst part of it all? They didn’t even need the whole suffocation bit! Everyone was dying either from lung cancer of starvation anyway – the whole oxygen bit was clearly just intended as an additional drama factor. A waste of my oxygen, at least. Geez.
On to number four! In this scene, Cooper is being given the mission details: he’s going to pilot a spaceship through a wormhole into a wholly different part of the universe. The bit that amused me was where they show him a very blurry space-picture, and Cooper, again has a moment of instant, perfect clarity. That is, he knows exactly what is going on for no apparent reason at all. All the other guy said was (paraphrasing): “There’s this space-time distortion near Saturn. Here’s some blurry pictures.” And as with the “Gravity!”-scene, Cooper immediately states: “Oh yeah, that kinda looks like a wormhole.” How does he know what a wormhole looks like? Pardon the boldface, but I’m genuinely puzzled by this – how is he able to identify something that he’s never seen before, probably never even seriously considered as a physical possibility before, from a poor-quality picture?
This offense is going to get much, much worse just a little bit further ahead, as Cooper conveniently happens to forget how wormholes work so the other characters can explain this to us, the audience – despite the fact that Coop is apparently capable of recognizing one from a blurry picture. Be prepared for more of this deliciously blatant exposition in the scenes to come – the movie is guilty of this trope a lot.
In the final scene before Cooper departs on his (probably one-way) space mission, he sits with his father-in-law on the porch of the farm, discussing the philosophical ramifications of the whole mission. I get that being an astronaut, leaving his family behind with a clear chance of never seeing them again for a variety of reasons, Coop’s got every reason to be melodramatic. The statement from the screenshot above, however, had me raising my eyebrows. As a man of science, surely he knows that of all species to ever have lived on the earth, 99.99% are extinct? And trust me, that is probably still a pretty conservative estimate. Sadly, as with all species to ever have inhabited our planet, we are quite likely to die here, at some point. As the movie depicts itself, we ultimately appear to have rather little hope of survival unless someone else comes and gives us a hand (certainly at the rate we seem to be going).
Let’s move on to more amusing matters – fail number five! For our next scene, we come to the bit I’ve personally dubbed: “Cooper being an idiot for no apparent reason.” In this scene, they’re in the spacecraft plotting their course of action right before traveling through the wormhole, and Cooper suddenly decides to forget what wormholes are.
This is one of the first of many moments where the movie abuses Cooper’s completely illogical ignorance of every single bit of cosmology ever as a way to explain physics concepts to the viewer. Now, if you’re ill-versed in such things, you might not notice, but as someone who actually knows all of this stuff, all I’m thinking is: “Why does this mister astronaut guy, captain of the mission, know basically jack-all of these big physics topics?” Surely, Cooper’s got a master’s degree in engineering. Even if he didn’t care much for these things, he would have known quite well that a wormhole isn’t going to be a two-dimensional object in 3D space.
In fact, while the explanation is mostly educationally sound, the fact that they’re talking about a 3D space-time distortion is a tad silly. Did both of them just conveniently forget that we’re also bending in the fourth dimension, making it even more complicated than it already is? It might be hilarious if it wasn’t so obviously contrived to simply explain some of the crazy physics. It’s really just lazy writing. The worst offense here, really, is when Cooper reveals he never even knew the basics of the system they were traveling to, such as the name of the black hole that plays such a crucial role in the film. How is it that no one bothered to tell our pilot any of the mission details?
But it gets worse yet: besides not knowing how wormholes work, he seems to also not even have a general notion that relativistic time dilation is a thing, despite having explained this earlier in the film to his daughter. They even go so far as to have him exclaim “whoa shit” when they explain that being so close to a black hole will cause for massive clock slowdown, to which they reply “that’s relativity for ya.” Really, Cooper? Who invited this guy to the space mission that’s supposed to save humanity? And who decided not to brief him on anything before sending him up into space? Seriously.
Next, I’d like to complain a bit (because that’s all I’ve been good for so far) about the characters’ statements that looking at the heart of a black hole, the singularity, would allow scientists to “solve gravity” – one of the most crucial plot points in the film.
I’ve got a very simple reply to this: what? How does that make any sense? A singularity is just that: a one-dimensional point of zero size and finite mass – or, if you prefer, all of the mass ‘eaten’ by the black hole confined inside an infinitely small point. By its very nature, all information about something is lost if we squish it into a singularity – every singularity is the same as every other singularity1. Looking at a one-dimensional point (which, I might add, happens to be invisible because it is infinitely small) will hardly help us solve gravity, thank you very much.
Our next moment of dodgy science happens once they visit the first planet – one so close to the black hole that every hour there lasts seven years on Earth. It had, however, been sending incredible promising signals from the original team, so our heroes decided to go and take a peek. They said it had water – how bad could it possibly be?
Upon landing they found out exactly how bad, as they are beset by something that Cooper initially guesses to be mountains (apparently his superpower of immediately guessing everything correct is fading) but which turn out to be waves the size of skyscrapers. Well, that’s just delightfully terrifying isn’t it? Makes for a good bit of suspense, surely – but my skeptic-sense is tingling like a rattling doorbell.
You see, the way they’re depicted in the movie (where they’re so large they don’t fit onto the screen at a scale which allows us to still make out the spaceship our characters are in) makes me think they’re bound to be at least over a hundred meters tall. To make matter worse, the characters have previously revealed to us that the planet has 130% of Earth’s gravity. With that much gravity involved, how the hell would these waves have formed? After all, they would need 30% more energy to reach the same height – and they’d need a monstrous amount of energy to get this tall regardless!
On earth, we’ve got what are known as monster waves; these happen when different wave patterns overlap and amplifying each other in just the right spot, and can result in waves up to thirty meters high. But still, if we’re being stingy and estimate this wave to be about sixty meters tall, that’s much bigger than any wave that has ever been observed on Earth – and we don’t even have to deal with the problem of increased gravity! And what’s worse, we’re not even talking about a freak wave – it’s shown in the movie to be a constant pattern of waves, which means this would be a relatively normal thing that happens here! I’m calling bogus on this one.
And now, on to my favorite bit of science stretching in this movie, as well as our final fail for the day.
It’s the frozen cloud planet! That’s right, the next planet our astronauts visit somehow has clouds that, despite being frozen rock-solid, still float in the air. Now, before we go shouting ‘pfffft LOL!’, let’s imagine what it would actually take for this to happen. After all, ice cubes can float in your water, while rocks sink. This is because of density: objects (or fluids/gasses) of greater density sink to the bottom, while those of higher density float to the top. This is why it’s okay to inhale helium to make your voice all squeaky, while it’s a bad, bad idea to go inhaling a balloon full of argon – the first is lighter than air, and so comes floating back out, while heavy gasses get stuck in your lungs, and you’ll end up suffocating in a room full of perfectly good air if you don’t have yourself strung up by the legs or such. Really [link].
So, technically, these clouds could float as long as the air beneath them is of higher density than they are2. However, there’s not a single known molecule in nature of which the gaseous state, at Earth’s gravity, is more compact than the solid state. To make matters worse, this planet has only 80% of Earth’s gravity, which means that the air is actually less dense than on Earth – the gas is bound to the planet less firmly! As such, I’m going to have to give this final one a big no-no as well.
And hey, guess what, folks? I’m through with complaining! Let’s end on a positive note, and look at the actual proper science shown in interstellar. For starters, there is a point where Cooper has decided to leave for his (potentially) one-way trip. The only thing left is to try and explain to his daughter why he has to go, and what that means – or at least to make a horrible attempt at such, anyway. To quote:
“When I’m out there, traveling at the speed of light or near to a black hole, time is gonna change for me.”
In the words of our ever-wise Doctor: Wibbly-wobbly timey-wimey! Yay for relativity (or, in the case of this movie: not so yay, but I’ll take what I can get). But how realistic is all of this time-slowing-down stuff, really? Well, if you’re wondering that, I’d like to point you to my previous article for a brief explanation of most of it. If you don’t feel like looking up the details right now, let me just say this: the writers actually got most (if not all) of their stuff right! Time dilation effects are very, very tricky, especially when trying to convey them realistically and still have them do work for you in dramatization – major kudos to the writers here.
My next but of really neat science focuses on the pretty screenshot from the movie that I’ve included above.
I just wanted to say I loved this shot. Not just because it is fabulously pretty, but also because it’s actually rather accurate. At first, I was thinking of calling filmmaker artistic shenanigans, because black holes are usually just that: black. Entirely devoid of light. By definition, it’s rather hard to see them against the background of mostly empty space, which inconveniently also happens to be black. So why should there be this enormous halo of light around it? It was then that I realized I’d forgotten one important effect of the extreme gravity involved: lensing.
You see, Gravitational Lensing is one of the most significant ways we have to detect black holes: the light from behind the black hole is curved around it because of the immense gravity, resulting in a weird ring of distorted light. We can see this across immense distances of space with a telescope, so just imagine what would happen if the black hole in question ended up filling your entire field of view – there would be a whole lot of light to focus, potentially already giving us the circle around the black hole we see here. Adding to this is the Accretion Disc – the bright ‘ring’ around it, looking not unlike those we see around Saturn. It’s very bright and energetic, and thus radiates a lot of light: I’d imagine this adds to the lens flare even more, explaining why they would both be the same color.
At this point, I’m going to be fair and admit that from about halfway in the movie actually manages to do fairly well overall – it either managed to not make many more obvious screw-up, or managed to glue my attention on the plot so tightly that I failed to notice the flaws that were there. And, after all my nagging, I’d like to end on a positive note. Because unlike a movie such as Gravity (the 2013 film by Cuarón, starring Clooney and Bullock), about which one could go on for hours and hours on end, Interstellar actually gets so many things right! From accurate descriptions of black holes to time dilation to wormholes, most of the cool-sounding science bits are very much in a totally scientifically correct way.
And, even more importantly: the movie is also actually good. The acting is great, most of the plot is gripping and compelling, and the movie had me glued to my seat, even in skeptic mode, for at least the last hour. What’s more, the musical score is amazing (and has received several awards), and the visuals are typically stunning – the view of the black hole is probably one of my favorite movie visuals of all time. All in all, Interstellar was just a hugely satisfying entertainment experience, and I’d recommend to anyone, anytime.
1. Attributes like mass and charge and spin notwithstanding, black holes are otherwise indistinguishable. The famous physicist John Wheeler once put this in the now legendary proverb (among theoretical physicists): “Black holes have no hair.”
2. Which would mean the gas could probably support your body weight as well – how cool is that?
Thorne, K. (2014). The Science of Interstellar. http://books.google.co.uk/books?id=PbWYBAAAQBAJ&printsec=frontcover#v=onepage&q&f=false