Faster Than The Fastest

Faster-than-light travel is a staple of space anime, appearing in various forms. Here we will explain why this is a necessity, how it is implemented and how much sense it makes.

When writing a story taking place in space, it’s easy to forget that space travel is terribly slow. This isn’t mainly because space rockets are slow, but mostly because distances in the universe are huge. In order to leave Earth’s orbit, rockets need to reach a velocity of multiple kilometres per second! This is much more than any transport system could ever hope to achieve on Earth, where velocity is limited because of air resistance.

This speed corresponding to our current technology is good enough when the story is bound to our solar system. In the manga and anime Space Brothers, two brothers dream of becoming astronauts, and the story taking place in 2025 stays reasonable with missions going towards the moon and the International Space Station. However, it would not be crazy to imagine a realistic story where the protagonists go to Mars, or even to Jupiter, Saturn or any of the solar system planets. Sure, that would bring a lot of technical issues, but it isn’t entirely impossible. Unmanned aircrafts have already been sent towards most planets after all. Of course, it might not be able to land on Jupiter, as it is a gaseous planet and doesn’t have a definite surface, but reaching all of these places in our solar system is still possible.

In most sci-fi stories however, staying in our solar system is out of the question. There are no habitable planets here (at least not easily!), while they probably exist somewhere else in the universe. We just need to get there, don’t we? With a fast enough airship, that should be possible. Well… not really. Reaching other solar systems might not even be possible for someone in their entire lifetime. The closest star from us — with the exception of our Sun — is Proxima Centauri, and it is situated 4.3 light-years away from us. That’s 40 thousand billion kilometres! A distance impossible to picture without doing some comparisons. If we put everything to earth-like scale and we imagine the Sun to be one metre away from us (don’t burn!), then Proxima Centauri would be about 270 kilometres away!

Proxima Centauri, as seen from the Hubble Space Telescope [ESA/Hubble / CC BY (https://creativecommons.org/licenses/by/4.0)]

When we talk about 4.3 light-years, we refer to the time needed by light to cross this distance. Light particles — photons — are massless, which allows them to reach a gigantic velocity of 300,000 kilometres per second. This is the fastest speed anything can achieve in our world, or at least it seems to be. However, this is obviously very inconvenient when writing a story in space, as it means it is physically impossible to reach another solar system in less than 4 years!

Here enters Faster-Than-Light (FTL) travel. A necessary step for stories taking place on a grander scale, while still trying to sound realistic. Being able to travel from one place to another faster than light itself becomes an obligatory narrative tool, as it would be impossible to do so otherwise. There are various ways to implement this phenomenon as we will see through a few examples.

In space opera Legend of the Galactic Heroes, space exploration was limited to the solar system before scientists developed a technology known as “warp” in the year 2360, before being perfected in 2391. Warp drives can therefore be attached to items like airships, which allow them to travel distances of multiple light-years in a moment. The only explanation given is the “bending” of space and time. That may sound like a far-fetched explanation, but this is actually one of the more reasonable ones.

After the warp is successfully done, a lot of energy is liberated and can damage the surrounding area. [Extract from Legend of the Galactic Heroes, directed by Noboru Ishiguro, written by Shimao Kawanaka, original story by Yoshiki Tanaka]

But what could “bending space-time” mean? Well, let’s imagine you are stuck on the surface of a sphere, for example our Earth, except flatter, without any mountain. Although the sphere is a three-dimensional object, this surface is a two-dimensional object, as you can walk the entire globe by going only in the north-south and west-east directions. You don’t need the third dimension, which would be linked to altitude (going up and down). So if you want to go from one side of the earth to the other side — for example from one pole to the other — the fastest way is to go around the sphere by the shortest way possible by walking on the surface. However, this isn’t the smallest distance between the two poles. You could go faster by going through the sphere. But if you do that, you’re using the third dimension, as you move up and down. Therefore, a smaller distance exists if you use the third dimension instead of restricting yourself to two dimensions.

This is similar with space-time. Space has three dimensions, but in the theory of relativity, time can be considered as a fourth dimension. We can consider space-time as a four-dimensional object. As in the previous example, it means that the shortest distance in 3 dimensions isn’t necessarily the same as the shortest one in 4 dimensions! And this isn’t only a crazy theory. There are observations showing that light isn’t always travelling in a straight line, but sometimes has a curved trajectory, because space-time itself is curved! This effect is known as gravitational lensing, as gravity is responsible for the bending of space-time.

An illustration of gravitational lensing. While the light appears to come from the direction of the orange arrows, the light actually follows the white arrows, as space-time is distorted by the very heavy object between the observer and the observed object. [Public Domain, https://commons.wikimedia.org/w/index.php?curid=112602]

However, although bending space-time is technically possible, it requires gigantic amounts of gravity and energy. Warping doesn’t explain how space-time is actually bent. In the Macross series, a similar idea is used, where spaceships can “fold” in a super dimension space where it is possible to travel much longer distances in only a fraction of the necessary time in “normal” space. However, again, the explanation is lacking.

There exist other theories though, which are more far-fetched, but give a more complete scientific explanation. One of them comes from 1998’s classic Cowboy Bebop. In this space western, spaceships can travel from places called Astral Gates, which are built in highly populated areas and allow FTL travel in-between these gates. This is explained by changing the rules of the universe in an interesting way. Every fraction of a second, the whole universe “phases out” and is replaced by a much more compact version of itself. The Astral Gates apparently allow for the ship to move during these phases where the universe is smaller and therefore covering large distances in short times. This idea is a bit crazy and isn’t based — as far as I know — on any existing physics theory. And while this could allow travel from one galaxy to the next very fast, Cowboy Bebop is very conservative with its Gates, as the story takes place in the Solar System and travelling from one planet to the other still takes a few hours.

A spaceship coming out of an Astral Gate [Extract from Cowboy Bebop, by studio Sunrise, directed by Shinichirō Watanabe and written by Keiko Nobumoto]

Many other theories probably exist out there! Different shows put different levels of thinking into their space travel mechanisms, but it is usually admitted that FTL travel requires technology that doesn’t exist yet, and might not exist at all. However, the limits of imagination are far beyond the ones of our physical world and people’s ingenuity allows the finding of new ways of travelling that sound very plausible. You just don’t need to think too much and to enjoy the faster-than-light ride.

Stories about science in anime, manga and more.

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