The science of Interstellar

We’ve already had a review about Interstellar, and we did say that we would talk about the science within the movie. But before we do so, let’s have some caveats:

1) It’s going to be pretty lengthy.

2) I’m assuming you have watched the movie, so I will be entirely liberal with the spoilers. Don’t come here looking for a primer for the movie – Interstellar doesn’t work like that.

3) I have a keen interest in science; and I try to understand as per a layman and explain in a similar fashion. I also did research, but I’m not writing a dissertation here. Still, please forgive me if I get anything wrong. In fact, feel free to correct me and post any relevant information or papers. The purpose of science it to build understanding, after all.

4) I will make some assumptions about your science knowledge. I don’t think you’d be interested in Interstellar’s science if you didn’t have at least some basic background in it. Don’t worry, we won’t be talking about equations and formulas.

5) Because we’re not talking about equations and formulas, I’m not going to concentrate on the logistics or the specifics of the science, because I assume that every movie is entitled to some artistic license. I’m more concerned with ‘is it even theoretically possible?’ as opposed to ‘is it possible given the speed of an unladen swallow blah blah blah?’

6) While the movie is a little bit overwrought at times, I still enjoyed it. The more you like something, the more willing you are to accept or overlook the flaws, so YMMV.

Ok, now that all the caveats in place, let’s start at the beginning…

Photo: Warner Bros

Matthew McCounaghey’s character, Cooper, is an ex-astronaut in a world that (he assumes) doesn’t need astronauts any more. For reasons not explicitly stated but what we can all imagine (pollution, over-farming, deforestation, you name it), the Earth has failed. Blight, some sort of airborne bacteria or parasite is affecting crops worldwide. I do not believe that they stated the origin of the blight, but IIRC the blight somehow derives energy from the nitrogen in the atmosphere. I don’t know how this is possible, as almost all life revolves around either carbon dioxide or oxygen to derive their energy in one form or another, but since there are exotic alternatives to photosynthesis (ie chemosynthetic life), I’m willing to accept it as a possibility.

The other statement is that very few food crops exist. Corn is one of the last viable food crops that is growing. I’m willing to assume that the movie meant food crops and not ‘plants in general’ because we do see grass, and if corn really was one of the only surviving plants on Earth, we would have MUCH more problems than just feeding ourselves. That being said, we don’t see any animals, and no mention of soy or other beans, so where are the humans getting their essential amino acids from?

Even so, I can still imagine this dystopian future happening already. Maybe not the specifics, but we already have climate change, droughts and food shortages in some parts of the world. It’s easy enough to extend the line and assume something like this may inevitably happen.

Cooper and his daughter Murphy works a farm. For some inexplicable reason, Murphy is haunted by a ‘ghost’. This is a Nolan movie that prides itself on science, and we know that it eventually works itself out, so let’s leave this here for the moment. After some furious decoding, it turns out the ghost is sending them to a secret NASA (SNASA!) where scientists have accepted that the Earth is inevitably doomed, and is working on a way to get off the planet.

Spacesuit up!
Spacesuit up!

We all know that there is no inhabitable planet anywhere near us, so it’s fortuitous that a wormhole has appeared near the edge of our galaxy. While it smacks of deus ex, I’m actually glad they used a wormhole. Amazingly enough, I rather have a wormhole conveniently placed than the hand-waved discovery of a warp drive. Also, the physics to get to the wormhole itself is relatively accurate, needing them to travel for the better part of a year, under rotation so as to maintain some form of gravity. In addition, while Plan A involves scientists working on a way to transport the human population into space, the physics involved dictates that Plan B, a bank of genetically diverse human eggs and sperm (and I would assume similar sets for plants an animals), be attached to the ship that Cooper and his crew are piloting.

Photo: Empire

The scientists refer to Plan B as a ‘population bomb’, and I am embarrassed that as a science fiction affocionado I have never thought of this solution to the problem of long-term space colonisation, the huge resources needed to transport full sized humans for what might be centuries. But it’s a thing, and many scientists and science fiction have discussed the premise.

Photo: Warner Bros

The wormhole is beautifully explained, and a thing of beauty, so let’s leave it at that.

As Cooper passes through the wormhole to (I believe) another star system in a different galaxy, they find 3 planets that could be inhabitable. All three circle a black hole, and the closest one is so close that the gravity of the black hole warps time itself; an hour on the planet is seven years on Earth. They try to circumvent this problem by doing a quick landing with their magical lander to save as much time as possible.

This is where my eyebrow raised: Can gravity affect time? Turns out it can. In fact, it does and it’s doing so in just about everything we do. The GPS satellites in space have clocks that run infinitesimally faster than clocks on Earth, because they’re in Zero-G and we’re not. We actually have to constantly update, sync and correct time on the satellites so that they don’t screw up.

But how does gravity affect time? Here’s my layman explanation: We know that gravity warps space. People have used the rubber-sheet analogy to describe space and gravity before, so we know that gravity warps space. However, physicists have also collapsed the 3 dimensions of space and 1 dimension of time into 4 dimensions of space time. Therefore, gravity should affect space time, of which time is a factor.

Even then, how the HECK can one hour over there be equal to 7 years on Earth? Would people even be able to survive? Turns out that is arguable (Phil Plait has two articles talking about that, if you read one post you need to read both), and I will let greater minds than I discuss the nitty gritty. Gravity does in fact affect time, and I am perfectly fine with stopping there.

Photo: Warner Bros

My bigger beef comes in two parts. First, there’s a reason why I call it a magical lander. If that tiny little ship can make point entries and exits into planets, why did Cooper’s crew need an Apollo 13 style rocket from Earth? I suppose it’s possible that they needed to bring up a lot of supplies, but it did damage my suspension of disbelief a tad. Second, all three planets orbit a black hole. Where is the star? Where is the energy that the planets are getting their heat from? It COULD have come from the black hole (some black holes give out radiation from the matter they swallow up), but if it radiates that much energy, how does Cooper survive getting close to the black hole in the later parts of the movie, let alone get into the black hole?

Once we get into the black hole, a whole new mess of concepts appear, most of which I’m in two minds over. Firstly, once Cooper passes the event horizon of the black hole, lots of strange things happen. We’ve never gone through a black hole, so I’m going to just ignore it. Cooper then wakes up in the ‘tesseract’. It might seem like nonsensical gibberish happening in the black hole – but if you can watch some Cosmos (the Sagan one, not Neil Degrasse Tyson, but both are awesome) it’ll help to to wrap your head around it: It was quite decent representation of a 4 (or 5) dimensional space to 3 dimensional beings like us. Here’s Carl Sagan explaning it way better than me.

And while I first assumed it was a hokey ‘love conquers all’ solution to wrap up all the ‘ghost’ plot points earlier in the movie, it’s also entirely possible that 3 dimensional beings like us might affect the world in such a way as Cooper and Murph and the watch. However, I still maintain that ‘love conquers all’ and ‘love allows me to find her in an infinite time’ is kind of a poor way to end a movie.

And then he somehow gets transported through space and he lives happily ever after. I suppose 5 dimensional beings could travel in space time just as easily as as we could walk around the block, but I have to admit that the ease and neatness in which everything was wrapped up kind of annoys me.

In spite of the ending and other plot issues (as I mentioned some overwrought philosophising), I still liked Interstellar. Yes, some parts seem hard to understand and could make your brain explode, but really, isn’t science a tool to help us understand, and isn’t science fiction a vessel for us to imagine?

If you wish to make an apple pie from scratch,
You must first invent the universe.
– Carl Sagan


Singapore’s resident Press Ganger, that is, the man to go to for Privateer Press’ WARMACHINE, and HORDES. Kakita also dabbles in Games Workshop’s WARHAMMER FANTASY and WARHAMMER 40K lines.

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