The ph-word in… Arrival

“The ph-word in” are posts about physics and other sciencey stuff in science fiction movies and shows.
Beware: It’s not about “the physics of”, like how could Star Trek spacehips actually warp in reality. It’s about “the physics [mentioned] in”, and what they mean.

“Arrival” is not a bad movie. Actually it’s an extremely beautiful, unique, well-made and impressive movie. Incredibly, it is based on a story by Ted Chiang (more on that later) and, even more incredibly, the “science” in its “science fiction” is linguistics.

When this is an actual screenshot from a Hollywood movie, you know something good’s bound to happen.

Still, some math (and physics under the hood) managed to creep in. In the first part of today’s post I’ll try to explain it, then I’ll add a few words on “Story of Your Life”, the short story on which the movie is based. Note: No spoilers beyond what you’d learn from the trailer; however, there is probably no point in reading this post before watching the thing.

On the movie

In Arrival, the resident theoretical physicist is Ian Donnelly, who mentions twice his plans for kickstarting communication with aliens that seem willing to cooperate:

Ian: I’ve prepared a list of questions, starting with some handshake binary sequences –
Louise: How about we talk to them first? Before we start throwing math problems at them.

Ian: Have they responded to anything? Numbers? Shapes? Fibonacci?

What is this stuff? The idea underlying Ian’s words is that one of the few conceivable things we might have in common with an extraterrestrial civilization is the knowledge of mathematics and of scientific laws. Particularly if said civilization managed to build spaceships that reach Earth.

Following from this, one surefire way of establishing a common language would be to express basic elements of mathematics, or basic laws of physics, which the aliens could easily recognize, and take it from there. This notion is a staple in the field of CETI (communication with extraterrestrial intelligence), and it has been used for the plaques onboard the Pioneer spacecrafts and for radio signals transmitted by humans into deep space.

By the way the idea is solid, and Louise mocking it as “math problems” is the usual “yea you scientists so smart and dumb at the same time” stereotype. I’ll forget that, given how stunning the rest of the movie is.

So, binary sequences refers of course to numbers written in only 0s and 1s, i.e. in the binary system. (Not only is it the most fundamental arithmetic system possible, it also avoids the bias in choosing another system: our preferential use of the decimal system only happens because humans have ten fingers.) They could just be series of integers, as in the Arecibo radio message, which begun with numbers 1-10 in binary form. Or they could be significant series of numbers, like the notorious prime numbers – the integers that can be divided only by themselves and by 1.

“Fibonacci” actually refers to another significant but simple series of numbers, the Fibonacci sequence. If you write down 1 and 2 and add them, write down the sum, and then keep adding the last two numbers, you get progressively 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233 etc.

As an aside, this sequence appears often in nature, for instance in the arrangement of branches and petals or the shapes of shells and hurricanes. The reason being that it describes growth, taking into account the whole of a system’s size and its latest “layer”, which is the one that gives off the next round of elements. Sounds universal enough to be noticed by aliens, and makes you look a little more sophisticated than just reciting 1-10 to them.

Physics also made an appearance in this very well-prepared whiteboard, which includes gravity and quantum mechanics, and implies the team’s effort to understand the technology behind the UFOs. (But, again, in this blog we deal with science mentioned in movies, not science behind what is happening in movies.)

On the short story

Mild warning: If you haven’t read the short story “Story of Your Life”, you might not want to read the rest, even though there are no actual spoilers. If you haven’t read the short story and haven’t watched “Arrival”, why are you wasting your time instead of doing that?

If I had been asked about science fiction authors whose work would never work in cinema, Ted Chiang would be a top answer. He only ever writes short stories, and we are talking just a couple of dozens of them so far. The action takes place mostly in subdued ways, and often the most important plot twists are the realizations that the heroes have. In addition, “Story of Your Life” is about linguistics and also about the absence of time. What could possibly go wrong?

Shockingly, nothing in the adaptation went wrong.

That being said…

“Story of Your Life” deals with two stunning concepts. Personally, I read it several years ago and it’s still one of the science fiction works that my thought drifts to spontaneously from time to time. But it has two pillars, and the cyclic timeless language that bends perception is the least important one, tremendous as it is.

The other is an almost never mentioned reality of life; namely that there are two types of people and sometimes it feels easier to have understanding between one of them and aliens than between the two. The protagonist belongs to one of them, her daughter in the other, and their gap is made very explicit notwithstanding their otherwise good relation. One can’t help notice that it’s the same protagonist who manages to communicate deeply with, well, aliens.

In this sense it’s a good move that the title of the adaptation was changed: this is definitely not about the story of the daughter’s life. Also, the movie daughter dies at a much younger age, in a non-preventable way, and there is no hint of a character clash – to be exact, it seems like the movie daughter would belong to the same type as the mother. My point is that someone took care in eliminating the second pillar of the story from the script, and I agree wholeheartedly. Good Hollywood movies having an inexpressible concept as their main topic don’t happen every day; let’s leave it to literature to deal with two of these at the same time.

PS: I hate ruining a half-good closing line, but. Among Ted Chiang’s works one can find the masterpiece titled “Understand”. Thank me later.

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