INTERSTELLAR - Between Science and Fiction

 

 Hello there puny humans,

it has been more than 4 months now that Interstellar came out, and since then, it has been one the most talked about movies of last year. Critics accuse fanboys of hyping the film too much and over-looking its mistakes, while fans of the movie are annoyed that people seem to deliberately nit-pick just because it's made by Christopher Nolan and they want to see him fail. Despite all that, it is undeniable that the science presented in Interstellar is amazingly accurate for such a fantastical and large-scale sci-fi adventure. Not only was Kip Thorne (one of the leading experts on gravitational theories) advisor and producer on the film, but other theoretical physicists like Clifford V. Johnson (i.a. science consultant for the Discovery Channel), and even the famous Neil deGrasse Tyson praised the movie for its realism. So which parts are fact and which are fiction? I've worked my way through tons of videos and articles to find out, and though I'm still no science expert, I think I am now able to break it down for you! But those who haven't had the pleasure of watching this film yet, be aware: There is spoilers ahead!  

1. Another One Bites the Dust

Scene from Interstellar

Christopher Nolan's movie starts back on earth in the late 21st century, where due to food shortage most people have become farmers. The land has dried out and huge sandstorms are plaguing the cities, forcing a lot of families to simply pack their things and leave their homes, and heavily affecting the health of those who chose to stay. If you ask yourself wether something like this could really happen or not, you might be surprised by the answer: It already has happened!

Photograph of a Texan Farm, 1935

Yes, during the 1930's in the southern plains of the United States (including Kansas and Oklahoma) agriculture and ecology in general were severly damaged by great dust storms. Just like in Interstellar, these storms had a big impact on peoples lifes. In fact, the interviews with the elderly people you see at the beginning of the film are taken from Ken Burns' documentary The Dust Bowl, where eye-witnesses of the so-called "Dirty Thirties" talk about their actual experiences of that time (with the exception of the ones with Ellen Burstyn playing "old murph").
This phenomenon was caused by the dramatically quick increase of agriculture in a short amount of time, which was the result of the government funding the cultivation of land. This could easily have happened in the film, as here too, the government is supporting the idea of people becoming farmers due to the food shortage.

2. Sleeping Tight
To travel as far of a distance as the crew of Nolan's "Lazarus" mission does, its members put themselves into cryo-sleep. This technique, which is based on the principles of an animal's winter sleep, does not exist yet, but agencies like NASA are doing a lot of research on that matter, hoping to use it for a manned Mars mission. Eventhough they have yet to come up with anything beyond the therapeutic hypothermia that is used as a medical treatment today, there are a few cases that lead them to believe that cryonics might actually work:
Mitsutaka Uchikoshi of Japan purportedly survived 24-days without food or water after falling in snow and entering a hypothermic state. Erika Norby, a one-year old, was revived after her heart stopped beating for over two hours when accident left her exposed to -20 C weather conditions and her core temperature dropped to 17 C. And in 1999 Dr. Anna Bagenholm, at 29 years old, was revived after her heart was stopped for 3 hours after being submerged under ice while skiing. So who knows, maybe one day this bit of fiction might become reality...

3. Holes in Space: The Worm ones
Of course to get to a whole different galaxy as far away as the one in the film, even cryosleep wouldn't have helped because it would have taken way too long. In Interstellar however, the crew manages to overcome this obstacle because of a little help they got from "them". And what "they" did was placing a wormhole in the perfect spot for the spaceship to take a shortcut.

A "two-dimensional" demonstration of a wormhole

Now wormholes are a highly theoretical construct. Yet, a lot of scientist believe they exist. Stephen Hawking explains it like this: It's a basic physical principle that there are no truely flat surfaces. Even something as smooth as a billiard ball has cinkles and crevices that could be seen if it was magnified enough. The same applies for the rug-like structure of space-time (see 5.). On a scale much smaller than atoms and more than a sextillionth of a millimeter, tiny holes or tunnels can be found in it. Linking either two places in the same time or two points in time at the same place. If these shortcuts were (somehow) able to be captured and enlarged many trillions of times, a spaceship would be able to fit through them. Another challenge however would be to stabilize the wormholes as they form, fall apart and reform in less than a microsecond.
So eventhough wormholes are not proven to exist, the movie Interstellar uses the most current theories about them. Also its visual design is quite accurate, because as said in the film itself: A hole in space must be three-dimensional and therefore more of a spherical shape.

4. Surfing Safari
After a juddey ride through the wormhole the spaceship lands on a planet covered in water. Just a couple of minutes have passed when the astronauts realize that what they thought to be a very high island on the horizon is actually a mountainous wave coming towards them. Not all of them make it back before it hits and so the crew has to deal with their first losses.
Naturally, a lot of viewers thought that the wave was just a little gimmick the writers made up to give their characters at least some kind of challenge, but here too, the events are scientifically logical. On earth, low and high tide are created by the gravitational pull of the moon. A "bulge" in the water forms right under it, but as moon and earth are both moving without our notice, it actually looks like the water is moving. In the film, the planet they landed on is said to be incredibly close to the black hole "Gargantua" which has a gravitational pull that is significantly larger than the moon's. As a result, the "buldge" is substantially larger here and appears to be one giant wave. The only thing the film does get wrong is that it would not have such a peak and be much less steep than portrayed on screen. But that just wouldn't look as menacing...

5. What time is it?
Water is not the only obstacle the crew of the Lazarus mission has to face after their first touchdown. Every hour that passes on this planet equals seven years on our earth. What sounds like a crazy reversed-Inception-dream-time logic is actually one hundred per cent possible and plausible.

space-time dilation

As we learned from Einstein's relativity theory, space and time aren't two sperate things, but rather one and the same, called "space-time". Imagine this quantity as something like a rug or a bed sheet. Now imagine that this sheet was elastic like rubber. Gravitation is able to bend space-time, which would be like if you put a ball in the middle of our rubber sheet. Around the ball the sheet would now stretch and get thinner, so that you'd have less rubber per square centimeter. The heavier the ball the thinner it would get, and the same can be applied for gravitation. The stronger the gravitation of a celestial body, the more space-time gets "stretched". In other words: we experience less time. It passes more slowly. Since Gargantua has extremely high gravity, every planet close to it must experience a very big space-time dilation, just as it is presented in the film.
This kind of phenomenon is in fact relevant here on earth as well. Some GPS satellites are so far out of our planet's gravitational field that their clocks must run a little slower in order to match the ones on earth.

6. Holes in Space: The Black ones
We've heard a lot about Gargantua by now, but what exactly is a black hole?

"Gargantua" from Interstellar

Mathematically speaking every object in the universe has a so called "Schwarzschild radius", which gives you the size to which said object would have to be compressed in order to basically become a black hole. Because what black holes really are is a region where mass is so dense that even light can't escape its gravitational pull. This is also why they are called "black" holes. What Interstellar demonstrates exceptionally is the way one would actually look from the outside. Using algorithms of Einstein's general theory of relativity, the animators of the film were actually able to create new scientifical knowledge about the way it bends light and distorts images (a.k.a. gravitational lensing).

coordinate singularity

So much for the outside. But the inside of a black hole is not one bit less interresting. As a result of its density, there is a singularity lying in its core. Within this singularity the quantities to measure our physical units become infinite, and therefore the rules of physics don't apply in the same way anymore. To understand this better you could look at a coordinate singularity. This phenomenon can be observed on a globe at the spot where the north (or south) pole is. Here, the longitudinal and latitudinal lines are all compressed in a way that their measurement becomes meaningless.
Now, if anyone (like Matthew McConaughey apparently) was crazy enough to jump into a black hole, it is wrong to assume that this person would die immediately. In fact, there is a point called the event horizon, which is where the black hole's pull is already strong enough for you to never get out again, but where you haven't reached the singularity yet. You'd probably even have a breathtaking view, but as soon as you left the event horizon you would get spaghettified. Yes, this is actually a term used by scientist to explain the horrible and (most likely) deadly stretch that your body would experience... 

7. The Tessaract (...not from Marvel)
This is where we go deeper into the fiction part. After his jump, Joseph Cooper doesn't look like a spaghetti at all (or dead for that matter). On the contrary. He lands. And where does he land? Well, behind the book-shelf in his daughter's room...
At this point in the film, we don't really know if this is supposed to be the inside of Gargantua or if "they" somehow transported him there before he reached the end of the event horizon (the latter of which actually being less and more plausible at the same time). However, thinking that all scientific aspects of the movie have been thrown out of the window by now would once again not do it justice. I will not discuss the exact content of the ending here (though I personally quite like the message of love transcending space and time), and instead will focus on its visualization:
The difficulty the filmmakers faced here is that Coop' is supposed to be in a four-dimensional room. As the movie explains as well, for four-dimensional beings traveling through time would just be what walking up or down a hill is for us. Unfortunately, a visible fourth dimension is literally unimaginable for our brains. Yet, Nolan still gives it his best. He and his animators tried to construct something similar to a tesseract, which is to the fourth dimension what a cube is to the third (or a square to the second). When rewatching the scene you will notice that the "tunnel" that Cooper is stuck in is actually made up of a lot of cubic shapes. Further, (and just as explained before,) he is able to travel forwards and backwards in time by simply moving up, down, left or right inside the tunnel.
Thus, it might be a very speculative, but also a very ambitious way to portray a four dimensional room.

8. Cooper Station - or: Very weird baseball

Once again, we don't know exactly how Joseph gets out of the tesseract, but eventually he is rescued by a near by space ship. When he finally awakes in the medical facility of "Cooper Station" he looks out of the window, only to see more ground where the sky should be and people walking around upside down. This scene reminded a lot of viewers of a certain image from Inception, when the architect Ariadne is playing with the laws of physics within a dream. The idea of living inside such a habitat however dates farther back than the release of that 2012 blockbuster. In his 1976 book The High Frontier: Human Colonies in Space American physicist Gerard K. O'Neill proposes a design of a cylinder shaped space station, that very much equals the one presented in Interstellar. But why don't the people walking on the top fall off? And how is gravity generated at all?

space-colony art (1970)

The idea of the "O'Neill cylinder" is, that it rotates at certain speed, so that the centrifugal forces create an artificial gravity on its inner surface. A speed of forty rotations an hour would be fast enough to produce the 9,8m/s² we have on earth, but slow enough so that it wouldn't create symptoms of motion sickness. Special walls of windows set across from mirror-walls would be pointing at the sun and open at "daytime" to help reflect the sun's light into the cylinder.
So even this time Nolan has drawn on real scientific theories...

Aaaand that's it! I hope you enjoyed this in-depth look at Interstellar. It was lots of fun writing and researching for it, and I hope I didn't bore you to death with my newly gained knowledge. What were you surprised about? What did I miss? What did I get wrong? How are Joseph Cooper and his dad-in-law drinking beer eventhough corn is the only existing grain?* Feel free to discuss any of that and more in the comment section, and thank you so much for reading!

Sincerely,
Your Cinemartian

*the answer: corn beer exists