James Darling and I were just blown away by the reception to Science Vs. Cinema: THE MARTIAN. We’ve long wanted to do another, but we’ve been busy, him with his Roddenberry project, and me with astronomy. But when ARRIVAL came along, we knew we had to find a way to do it. I saw it at the Toronto Film Festival (read my review here), and we started working on this episode soon after. We also went to some LA events, up to the SETI Institute, and interviewed experts who worked on the film. We got our dream list of people for this, including interviews with stars Amy Adams and Jeremy Renner, short story writer Ted Chiang, screenwriter Eric Heisserer, SETI researcher Seth Shostak, and scientific consultants Jessica Coon, Stephen Wolfram, and Christopher Wolfram. There are a few extra surprises in there as well. The first few acts are spoiler free, so you can start watching even if you haven’t seen the film. Just jump ahead where I warn you in the last act. So here it is, Science Vs. Cinema: ARRIVAL!
If you like that, you can subscribe to the channel here. I can’t tell you how much fun it is to spend so much time with some of the top minds on the planet chatting about linguistics, the possibility of alien life, and communicating with them. We have hours of extra material that go much, much deeper. So we hope to release some extended interviews on the channel in the coming weeks.
The production of this episode was a bit different than before. I wrote the below companion article months ago before even starting work on the episode. As a result, the show is different from, (and much better than), the article. However, the article allows me to go deeper on certain subjects, so it is still worth reading. There are spoilers below, so see the move first. And as always, follow the links for deeper reading on the subjects discussed. Here’s the article:
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Watching Carl Sagan’s TV shows and reading his books were a big inspiration for me in becoming an astronomer. He was one of the pioneers in the Search for Extraterrestrial Intelligence (SETI), and his enthusiasm certainly rubbed off on me. I even did some SETI research as an undergraduate, and early in grad school helped look for planets around other stars. The thing that fascinated me most about the prospect of finding some alien civilization is the puzzle of how you communicate with them. Since they are likely to be more advanced than us, if you can figure that out, you get instant access to a much deeper understanding of the cosmos.
One thing I love about ARRIVAL, and the short story it is based on, STORY OF YOUR LIFE by Ted Chiang, is that it doesn’t just take known ideas about ways to communicate with aliens, and build a story around it. Instead, it treats aliens as something truly alien to us — creatures who think in a way we can barely fathom.
Here I’ll start by covering the some of the traditional SETI ideas, then expand on how this would change for “in-person” communication, and finally discuss the language and physics implications of what we see in ARRIVAL.
ALIEN PHYSIOLOGY
The vast majority of TV and movie aliens are remarkably humanoid. There are plenty of reasons for this. For a start, it is a hell of a lot cheaper to put some makeup and prosthetics on somebody than it is to create an alien from scratch. But an even deeper reason is that the usually the audience needs to relate to these beings, and we have tons of brain circuitry devoted to reading other humans.
ARRIVAL is different — first it is a big budget science fiction film, so cost isn’t as much of an issue. But also, the exotic, unrelatable nature of the aliens is a big plot point. So I’m really happy that the aliens look truly alien.
The chances of real aliens looking humanoid is pretty small. It is true that some have argued that things like legs, arms, a face, eyes, a mouth, etc. are so useful that they may well be universal. But just look at the diversity of life on Earth — it is pretty incredible. Hominids are a very tiny percentage of all the species. And that’s still a biased picture because we share a huge percentage of genes with all life on Earth. Alien life would have a different genetic starting point (if they even have genes), different boundary conditions (like atmosphere, pressure, temperature, and gravity), and different selection pressures. Of the trillions and trillions of events that shaped us, they’ll have that many different events that shaped them.
KLAATU BARADA NIKTO
How do you communicate with beings where you share no cultural heritage, and maybe not even the same senses? One way is to use math and physics. That’s the one thing we’re guaranteed to have in common with any other galactic species. There are two kinds of communication — “in person” or at a distance through transmission of signals.
The SETI as currently done on Earth is a search for (usually) radio or laser signals as signs of an intelligent civilization. How do you even look for a signal when you have no idea where to start? To demonstrate intelligence you might want to broadcast something that can’t be mistaken for a signal in nature. So you might want to broadcast prime numbers — those exist independent of culture. But what number system do you use? We use base-10 because we have 10 fingers, but who knows what aliens would use? Maybe you’d want to use the simplest possible — binary. Well, that’s the simplest in principle, though it took our species a lot of time to develop it.
From there you can build up symbols to represent other things, such as mathematical operators. If I said:
1 ? 1 # 2,
1 ? 2 # 3,
2 ? 3 # 5,
and so on, you’d quickly figure out that “?” stands for addition and “#” stands for equals (the symbols might be in binary, but you get the idea). Then you can establish concepts such as true and false, or yes and no with mathematical equations. You can generalize to ideas of one, few, or many, and introduce sets to get across the idea of something being inside or outside a group, and maybe even "us" and "them."
Then you can bring in physics. Any advanced species will know all wavelengths associated with emitting and absorbing light from all elements. Start with hydrogen. You can then spell out the steps in hydrogen fusion to indicate you are talking about a star. You can establish a length scale, since light wavelengths are lengths. And you can establish mass using the mass of the hydrogen atom. Then you can get into the masses and properties of planets in the solar system, and let them know that we're on the 3rd planet, which has an oxygen atmosphere and water.
But at some point you are limited by the vocabulary you can easily build. How do you explain what a human is? So you might want to draw pictures, either in 2 or 3D. How do you establish that some transmission is a picture? The simplest is just to use 1 for a dark pixel and 0 for a light pixel. Then make the length and width of the picture either be a perfect square or be prime numbers to minimize the number of ways to format it.
These are some of the concepts used by Frank Drake when he sent a message to the globular cluster M13 in 1974 using the Arecibo telescope. This was really just a symbolic gesture, since it would take take 25,000 years for the message to reach its destination. The message is pretty primitive, but see if you can decode it (it is a bit easier with color added, though the original didn’t have color).
Outside of sending signals, you can imagine sending information on some artifact. That's what the gold plaque on Pioneer 10 is. Since it was to be the first object to leave the solar system, it was given a sign explaining where it came from in case it was discovered by some intelligence in the future. It has a man and woman, a depiction of the solar system, distances given in terms of a hydrogen wavelength, and a map of pulsars in to pinpoint out location in the galaxy.
After that, we sent a "golden record" on Voyager. Curated by Carl Sagan and Ann Druyan, it had greetings from Earth, and examples of Earth sounds and music.
More generally, these are examples of Bracewell Probes -- sending the equivalent of snail mail to another star system. The idea is that you send an artifact to a star filled with information. Just like sending a car full of hard drives can have a higher bandwidth than the Internet, sure it takes a long time, but you can ultimately send more data this way. And it can stick around instead of being transitory.
Everything changes when you can high five an alien, or punch it in the face. Now you can have instantaneous back-and-forth communication, and even show pictures, use symbols, or draw things. But it comes with the downside of potential miscommunication, and violence. This is the fascinating regime of ARRIVAL.
Many previous films have modeled themselves on the only examples we have from history -- first contact between native people and some more technologically advanced civilization coming in via ship. In science fiction this is most often told from the underdog "humans triumphing" perspective: WAR OF THE WORLDS, INDEPENDENCE DAY, MARS ATTACKS!, etc. There are other sub-genres where the aliens are benevolent (CLOSE ENCOUNTERS OF THE THIRD KIND, ET, COCOON), and/or scolding (THE DAY THE EARTH STOOD STILL). James Cameron tells it the other way -- we're the technologically advanced imperialists, and the creatures we're invading are either terrifying (ALIENS), or benevolent (AVATAR). But few have told it the way it has happened just about every single time throughout Earth’s history: the newcomers have such technological and immunological superiority that they utterly decimate the native population.
WIBBLY WOBBLY TIMEY WIMEY
A major plot point in ARRIVAL is that time is nonlinear. In other words, the future can affect the past. This is an old trope of science fiction, but stories deal with it in different ways. You can take the many worlds interpretation of quantum mechanics so that each jump in time spawns a new reality, and you can have many simultaneous versions of reality (e.g. the Mirror Universe on STAR TREK). Or you can have a single timeline where if you change something in the past, it changes the one true future (e.g. BACK TO THE FUTURE, STAR TREK IV). This, of course, can create a paradox. What if you go back in time and kill yourself so that you can never go back in time?
There is another possibility, that time travel must obey what’s called the Novikov self-consistency principle. That says that you can’t go back in time and do something that will cause a paradox. If you try to kill yourself in the past, some law of physics will prevent you from doing so.
There are solutions to the theory of General Relativity that produce what are called closed timeline curves. Basically, these are loops in spacetime. In principle you could produce them with a wormhole. Novikov, Kip Thorne, and others discussed this in a paper in 1990. My colleague at UCSB, Joe Polchinski, then argued that the cleanest way to think about the problem is in terms of billiard balls. A ball could fall into a wormhole, come out another end in the past, and knock itself away from ever falling in. However, there exist solutions such that the ball just gets a glancing blow, so that the ball in the past knocks ball into the hole in the first place.
But what if you could go through a wormhole, come out in the past, and stop yourself from going into the wormhole? This can’t happen under the self consistency principle. So if the self-consistency principle is true, humans must not have free will.
In ARRIVAL, the Chinese general tells Dr. Banks (Amy Adams) something in the future, but she “remembers” it in the present. But then you have to ask — when she got to the future, she would already know the information, and the general would know that she knows it, so why would he tell her?
The most self-consistent answer is indeed that humans have no free will! The general only ever does one thing — he has no choice in the matter. It gets even more interesting with the protagonist, Dr. Banks, because she starts to realize how everything works. In the movie you are left with this puzzle — why would she do everything in the future exactly as she has foreseen it? The short story goes a bit deeper into it, revealing that she more or less has no choice in the matter — she’s almost a puppet of fate. The same is true of the aliens (heptapods), although they don’t see it that way since their conception of time is so different.
PUTTING THE F IN PHYSICS
It isn’t dwelled on in the film, but the short story goes into a fair amount of detail about how the aliens have a very different conception of physics than we do. Since we see time as a series of events, our interpretation of physics works along these lines. But since the aliens see time all at once, their physics is instead based on that.
In the book they use a light ray traveling through air and water as an example. A light ray moving in one direction in air bends and travels in a different direction in water, based on the index of refraction of water. We think of this in terms of cause and effect. The light hits the water and then bends. But the curious thing is that the light ray takes the minimum possible travel time to get there. If it had traveled farther in air, then bent at a steeper angle to reach the same destination, it would have taken more time. Or if had traveled a straight path, which would have minimized the distance traveled, it would have taken more time.
In fact, calculating the path of the light ray by minimizing the time traveled is called Fermat’s principle of least time. But it requires knowledge of the end point of the light ray to do the calculation. How did the light ray know where it was going to end up before it started? ARRIVAL has a natural answer — there was only ever one possible path for the light ray. There is no cause and effect — that’s an illusion caused by our perception that time is a stream of events.
Fermat’s principle of least time is actually incomplete. It is more correct to say that light rays follow an extreme path. More generally, you can conceptualize this in terms of a principle called “action.” In physics speak, that’s the difference between kinetic and potential energy, integrated through time. That’s weird to us, and requires calculus, but fundamental to the heptapods. Meanwhile, things that are simple to us are weird to the heptapods, like velocity or kinetic energy. That’s because they are only valid at a single point in time.
This a such a profound concept, and one of the things that makes STORY OF YOUR LIFE one of the greatest science fiction short stories of all time. The one thing I’ll ding ARRIVAL for is that they didn’t go into the physics differences much at all.
LANGUAGE MATTERS
In the film, the premise is that as Dr. Banks learns more about the alien language, she starts to think like them. This idea that our language about time can affect how we perceive time is an extreme version of the Sapir-Whorf hypothesis. That basically says that the structure of your language can affect the way you think about the world. (You can find a fascinating article on this by linguist Guy Deutscher here). On some level this has to be true — many languages have gendered nouns. I remember a native French speaking friend of mine being dumbfounded that I didn’t think of a chair as feminine. I was just as incredulous that he did. But is this enough to matter? Is this enough to alter our perception of reality in a meaningful way?
Many ancient languages did not have a direct translation for the word we’d call in English “blue.” Homer never uses it in “The Odyssey,” though he describes the sea. Blue is also absent from other ancient Greek texts, the Koran, the ancient Hebrew Bible, and ancient Hindu and Chinese texts. Maybe this isn’t as surprising as it first seems — there are almost no animals or plants that are blue. Blue pigments don’t really exist in nature, which is why so few animals are blue. Instead, the few blue animals use microstructures in their shells or wings to scatter light in a way that appears blue. Sure, the sky and sea are “blue,” but they aren’t the same color as each other, and are in fact many colors depending on the time of day and weather conditions. Egypt had a word for blue, but that’s probably because, unlike the other cultures, had a dye for it.
If you believe the strongest form of the Sapir-Whorf hypothesis, ancient cultures with no word for blue would then be incapable of seeing blue, or at least unable to differentiate it. See this Radiolab episode for some speculation on that. While we can’t know with any certainty what ancient people thought, we can do some experiments with people with similar existing languages. Much has been made of the Himba tribe in Namibia, which it is said has no word for blue. This was covered in a BBC documentary (now removed from YouTube, but written about in BoingBoing, Business Insider, IFL Science, etc.), where they show what looks like an obvious blue square in a pattern with other green squares, and it is said that the people there mostly can’t tell the difference.
However, it doesn’t look like that research was ever published, and seems to have been exaggerated and sensationalized. This whole idea that if you don’t have a word for something you can’t perceive it has been thoroughly debunked. There’s a color spectrum, and different cultures divide and name it in different ways. But just because you name things in different ways, I just can’t imagine you see something obvious completely differently. Americans may not have previously had a single name for color #a442a0, but that didn’t change our perception of it. And besides, after the extraordinary XKCD color survey, I think we can all now agree that the name should be Ugly Purple.
BRINGING IT FULL CIRCLE
Communication between members of a species even on Earth is poorly understood. There are more than 6000 human languages in the world, many with very different rule systems. And the forms of animal communication are even greater. Some use light, some use chemical signals, some make sounds, and some sing songs. But only one has writing. The possibilities out in the cosmos are even more varied. Do some species communicate with electromagnetic waves? Might some use images?
I love to see this stuff explored in science fiction. Who doesn’t love the episode “Darmok" from STAR TREK: THE NEXT GENERATION (It’s the one where Picard has to to understand an alien with an allegorical language). These kinds of stories push our thinking to the edges of what’s possible. And they cause us to reflect on our own condition. That’s what great science fiction is all about. And ARRIVAL is truly great science fiction.
- Copernicus (aka Andy Howell). Email me or follow me on Twitter.
