Astrotropes: Wormholes

Wormholes show up a lot in fiction, don’t they? I’ve seen the concept reiterated several times in various different ways, in everything from obscure sci fi novels to high budget movies. Which makes sense really, because it’s a compelling idea, particularly in a universe where everything tantalisingly nearby is actually surprisingly far away, and the maximum speed limit of physical objects in our Universe is disappointingly slow.

This article discusses Interstellar, Thor, Thor Ragnarok, and The Avengers, but any spoilers are mild at best.

Fictional wormholes have become so common that we even have related oddly specific tropes, like the scientist explaining how they work by folding a piece of paper and sticking a pencil through it. We’ve all seen some variation of this in sci fi, right? The basic concept and its sci fi trope are quite firmly lodged in our collective consciousness – which is perhaps testament to the fact that general relativity is based on such intuitive concepts. There aren’t many other scientific theories which are so widely popularised. The question is, how realistic is all of this? And do wormholes really exist? And if they do, can we use them for travel like this?

Unfortunately, that’s not so easy to answer. Working with Einstein’s theory of General Relativity, wormholes are theoretically possible – by which I mean that theorists have found valid solutions to Einsteins theories which contain wormholes📝 which means they could exist without breaking the laws of physics. In 1916, Karl Schwarzschild first published his work on Einstein’s theory, known as the Schwarzschild Metric, which contained solutions leading to Schwarzschild Wormholes. Another often-used term comes from a paper published in 1935 by Einstein and Rosen📕, giving the name which fans of Marvel movies will recognise – an Einstein-Rosen Bridge.

The Marvel Cinematic Universe has done quite a lot to popularise the name actually, with Einstein-Rosen bridges being a recurring theme in several of the movies. Notably, Jane Foster explains in the first Thor movie that the Rainbow Bridge of Asgard🌈 is actually an Einstein-Rosen bridge. The term is casually mentioned again in Thor Ragnarok by Bruce Banner, though the wormhole in question has a much more hilarious name.

But while the terms “wormhole” and “Einstein-Rosen Bridge” may be essentially synonymous in modern usage, they didn’t actually come from the same place. Schwarzschild never used the word, and nor did Einstein. That dates back to a physicist called Hermann Weyl, who published a paper in 1928 about a theory of matter which discussed electromagnetic field energy and “one dimensional tubes”. His work inspired John Archibald Wheeler to coin the name “wormhole” in a paper published in 1957.

❝ This analysis forces one to consider situations… where there is a net flux of lines of force, through what topologists would call “a handle” of the multiply-connected space, and what physicists might perhaps be excused for more vividly terming a “wormhole”.❞

Misner & Wheeler (1957)

Interestingly, this means that the first piece of fiction to use the concept of wormholes actually predates the word. In 1931, Jack Williamson published a short story called The Meteor Girl. In it, a crashed meteorite is imbued with some kind of mysterious energy, and the protagonist uses this, together with his knowledge of Einstein’s theories, to create “a distortion of space-time coordinates” which is used to travel through both space and time.

The idea has resurfaced from time to time in fiction. Contact, by Carl Sagan. His Dark Materials, by Philip Pullman. The Algebraist, by Iain. M. Banks. One book by John G. Cramer is literally called Einstein’s Bridge🚀. There have been a huge number of wormholes depicted in TV and cinema too, whether in serious stories or in comedies, and whether they’re being used to travel to a distant part of the galaxy or just to send your enemy to meet his moosey fate.

The interesting thing about fictional wormholes as a trope is that just the mention of the word conjures an image into our minds. A circular, 2-dimensional hole floating where a hole has no right to be. Bonus points for some kind of light streaming out of it, glowy light effects inside it, and possibly some swirly stuff surrounding it. The Barzan Wormhole in Deep Space Nine is a textbook example. Sometimes the artists and cinematographers involved might even make a point of showing that this thing is completely 2 dimensional, with only one side, like in The Avengers.

The fun thing is that while we may be familiar with the idea, it’s actually pretty mindbending when you look closely at it. Think about it. Everything – EVERYTHING – in our real world experience is three dimensional. We may think of paper as 2D, but it isn’t. It’s just that one of its dimensions is very very thin. Even a single sheet of graphene is 140pm thick. But wormholes in fiction are literal holes in space, which appear impossibly thin and only actually have one side. The one above New York in The Avengers isn’t even visible from the other side.

Which means that thanks to modern cinema, we’ve managed to take a topological impossibility and make it not only familiar but expected. Which feels quite impressive. So ubiquitous is this particular depiction of a wormhole, that showing any other kind subverts the audience’s expectations.

Of all the wormholes I’ve seen in cinema, I think the most interesting (and possibly the most accurate) image was the one shown in Interstellar. I thought it was quite an enjoyable film, but I know a lot of other people found it… less so. But then, I’ll admit, some of my favourite things about the movie were the visualisations. The wormhole was definitely one of my favourites, because it’s one of the few times I’ve seen one shown as a 3D object.

And that makes sense! Why would a wormhole appear in 2 dimensions when it’s a hole in 3 dimensional space? We visualise these things in 2D because it’s easier for our brains to process and relate to, but I’m not sure that’s logical. Planets have a 3 dimensional gravity well, and black holes have a 3 dimensional event horizon, and both of these things follow the same Schwarzschild Metric as a wormhole – it’s a general vacuum solution to the Einstein field equations, and it’s spherically symmetric.

Unfortunately, when the protagonists of Interstellar flew their spaceship into the wormhole, it apparently reverted to a more typical tunnel-type effect. And I mean, don’t get me wrong, that’s by far the easiest way to imagine how it might look, but it doesn’t quite seem right in this case. Drilling a hole in a piece of wood creates a pair of holes in 2 dimensional surfaces linked by a 3 dimensional tunnel. So if you had two 3 dimensional holes, they’d logically be connected by a… 4 dimensional tunnel? And 4 dimensional objects are difficult to visualise and even more difficult to comprehend🤔.

So imagine a wormhole like this in 3 dimensions, and imagine light and objects can pass through it freely.. On its “surface” you’d see an inverted image of the space surrounding the other side of it. If it was orbiting a planet or a star, you’d be able to see an image of it on the surface.

The way I see it, entering a 3 dimensional wormhole like this would be a much more mindbending experience. I think it might go a bit like this. Like with falling into a black hole, it may not be immediately obvious when you’re actually inside it. As you move towards the 3D orb looking thing, like in the image above, the space around you would appear to recede behind you, and the wormhole in front of you would appear to expand and flatten out.

You’d probably reach a point roughly in the centre of the wormhole where you’d see circular, fisheyed projections either side of you. The one behind you would show an image of the space which you’d just left behind, complete with any familiar constellations, stars, or planets within view of the wormhole. The one in front would show the same kind of image, with the region of space at the other side of the wormhole.

As you continued moving forwards, the image from the wormhole’s other side would appear to expand until eventually it would surround you and the region of space you came from would appear to be on the “surface” of a spherical wormhole behind you. This is when you’d know you’d travelled through it and arrived on the other side.

At least, this is how I’d imagine it to work. This also assumes that you can both enter and leave, and that part’s less certain. Given that a wormhole uses the same kind of warping of spacetime that a black hole does, there’s always a possibility that you wouldn’t be able to leave. If that was the case, a wormhole might appear very much the same as a black hole from the outside and might be similarly inescapable for anyone or anything which might enter it – photons included.

Needless to say, that might throw a spanner in the works for anyone trying to travel through such a wormhole. Always make sure you won’t be trapped for eternity before you tell anyone that you’re ok to go.

Admittedly, it’s not so much that it’s slow and more that it’s slow compared to a human lifespan. Or maybe it’s that space is big…?

📝 A lot of this kind of theoretical physics feels somewhat esoteric, involving looking at sets of equations and finding solutions to them which make sense in the physical world. That last part is what makes them valid. Being as equations are equations, you could put any numbers in and get any numbers out, but if those numbers tell you things that contradict the laws of physics, then your solution isn’t valid. Alternatively, some things may be valid if certain things exist – matter with negative mass or negative energy density, for instance. We have no way of knowing whether those things actually do exist, but given how weird the Universe is turning out to be, who knows what’s still waiting to be learned!

📕 Einstein, A. and Rosen, N., 1935. The particle problem in the general theory of relativity. Physical Review, 48(1), p.73. – I dare you to find a way to cite that in your thesis!

🌈 One of many elements from the Thor comics that’s based on actual Norse mythology, incidentally.

🤔 After reading Hyperspace by Michio Kaku one summer, I found myself mildly obsessed with imagining things in higher dimensions – summarised quite well by Carl Sagan in Cosmos. Or trying to, in any case. I actually became quite good at imagining 4D objects intersecting 3D space and visualising rotation 4D hypercubes (better known as tesseracts, which are no relation to the McGuffin in the MCU films). One thing I never managed to visualise though, was a 4D hypersphere (a glome). Turns out, I can imagine straight vertices receding into another dimension, but curves just warp my mind. If you never have, you should try this sometime. It’s fun!

trope is a recurring theme in any narrative which conveys information to the audience. These are snippets of information which have somehow ended up in our collective subconscious as ways in which storytellers have gotten their points across. Overused tropes end up as clichés.

This article includes images from Thor Ragnarok, Interstellar, The Avengers, Star Trek: Deep Space Nine, and Contact. All images are used here for the purposes of review, criticism, and education in accordance with Fair Use/Fair Dealing policies.

About Invader Xan

Molecular astrophysicist, usually found writing frenziedly, staring at the sky, or drinking mojitos.
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