In the fantasy world of Brandon Sanderson’s Mistborn book series, magic users known as Allomancers, Feruchemists, and Hemalurgists can bounce themselves back and forth between metals, store their own luck away for a rainy day, or (bloodily) steal these powers away from others. In the first Mistborn trilogy, the characters with these powers make war in a somewhat Victorian setting and not once does an Allomancer think “what if I propelled myself so far and so fast that I left this entire planet entirely and visited another star system?”
But we do. Because an Allomancer’s magical manipulation of a fundamental aspect of the universe may hold the key to connecting ALL of Brandon Sanderson’s books!
Although you don’t need to know this in order to fully enjoy Brandon Sanderson’s works of fantasy, sharp-eyed and sharp-eared readers have figured out that most of Sanderson’s novels exist within the same fictional universe, called “The Cosmere.”
This Cosmere includes Warbreaker, Elantris, and the Stormlight Archive and Mistborn book series, among other tales. It has been slowly hinted that the worlds contained in these stories exist as planets within their own separate solar systems. We’ve also seen a character by the name of Hoid appear in more than one series. Considered together, this suggests that there is a method that Hoid utilizes to travel between solar systems in the Cosmere. Is it a wormhole? Or is it a spacecraft capable of traveling faster than light?
So far we haven’t seen any societies or characters in the Cosmere novels with technology advanced enough to have faster-than-light travel, but we know that eventually there will be a Star Trek-esque science fiction Mistborn trilogy and that according to Brandon Sanderson it will be a trilogy that can’t be published until further material has been written about the Cosmere itself. Essentially, there’s more we need to learn before we know how Hoid (and perhaps others) travel from system to system. If this traveling method will be explained in a Mistborn trilogy, then it stands to reason that the method for traveling faster-than-light will be developed utilizing Allomancy, Feruchemy, Hemalurgy, or a combination of the three powers.
Thankfully, these powers are also the Cosmere magic systems we currently know the most about. Even better, the latest Mistborn novel The Alloy of Law (and presumably its forthcoming sequels Shadows of Self and Bands of Mourning) introduced an ability that may be key to figuring out how faster-than-light travel can be achieved using allomantic powers.
(For a quick refresher on the basics of these magic systems, duck into Martin Cahill’s great primer here.)
Now let’s investigate some possible methods for traveling faster than light.
Possible Method #1: One Big Push
Allomancers who burn steel and iron are capable of pushing and pulling on nearby metals, respectively, using their body as an anchor or a piece of metal attached to a heavier anchoring object. Those who burn steel are known as “Coinshots,” on account of how fun it is to “push” coins away from yourself like you’re a human tommy-gun. But what if a Coinshot were powerful enough to push a small spacecraft into sub-light speeds? Since “pushing” by burning steel is the simplest way we know to put an object in motion, let’s investigate what it would take for a Steel Misting to move a spacecraft.
Coinshots have limits to their abilities: they cannot push metals that are embedded within a living body, or too thickly covered with another material, and they must be heavier than the object they’re pushing in order for that object to move. There is also a distance limit in regards to what is available in the surrounding area for a Coinshot to push. It’s important that we keep these limits in mind when thinking of the type of craft that would be needed to take full advantage of an allomantic push.
Allomantic pushing is an end-positive action, meaning energy is created from the process of burning steel. There is a limit to how much energy a single Coinshot can create from burning steel, but we can raise that limit by employing ” Nicrobursts,” allomancers who burn the metal Nicrosil, which allows the Nicrobursts to amplify the allomantic effects of the Coinshot. We’re also not limited to just one Coinshot/Nicroburst combo. We can use as many as will fit in the physical space between the spacecraft and its launching point.
[Edited to add: I initially confused Duralumin users, which eliminate an allomancer’s metal stores, with Nicrosil users, which amplify an allomancer’s metal stores. The intended allomancer’s are actually Nicrobursts. Onward!]
For reasons that will shortly become apparent, the make of the spacecraft is not entirely important as long as it contains exterior metal to push upon, so we currently don’t need to factor in the added weight for crew quarters, radiation shielding, and other necessities for space travel. To attain a greater speed with less power, the craft should certainly be small and light, so let’s say that for the sake of this thought experiment the craft is a spherical pod akin to the vessel that Dr. Arroway used to travel through the wormhole in the movie Contact.
Now we need to know how much force a Coinshot can apply, as well as the weight of the spacecraft. A Coinshot can propel the weight of a copper coin (3 grams) to the speed of a slow-moving bullet, more akin to a musket (370 meters per second) as opposed to a modern rifle (1200 meters per second). Coins fired in the Mistborn series of books have been known to be as fatal as a gunshot, but they have not been demonstrated to have the organ-liquifying power of a high powered rifle, so let’s say that Coinshots are a little more powerful than muskets, small rifles, and some handguns, and give them a top speed of 500 meters per second. Now we know that a Coinshot can propel 3 grams at a speed of 500 meters per second.
The spacecraft pod is the equivalent of a large-sized satellite which, according to this forecast of satellite launch costs, weigh about 6500 kilograms, or 6.5 million grams. This spacecraft pod is also being launched from the surface of Scadrial, the planet that Mistborn takes place on, in order to preserve the Coinshot. If the pod was launched in space, the force needed to push the spacecraft would end up throwing our Coinshots into space at the same speed in the opposite direction. (Possibly back into the atmosphere of Scadrial, making for a deeply unpleasant skydive.) The Coinshots need to be situated in the gravity well of a large body in order to remain the stationary. If we assume that Scadrial and Earth are roughly the same size, then Scadrial’s escape velocity is 11,200 meters per second. The Coinshot/Nicroburst Mistings need to be able to push 6500 kilograms up to a speed of 11,200 meters per second. That weight and that speed are the numbers we need our Coinshots and Nicrosil Nicrobursts to exceed.
How much push can we get out of a Coinshot/Nicroburst combo, then? We don’t know the exact rate of power gain that flaring steel gives to its user, as that seems to differ between allomancers, but let’s be generous and say that a Coinshot flaring steel and getting amplified by Nicrosil results in a push that is 50 times stronger. We then get this range:
Weight @ Speed
3 grams @ 25,000 meters per second
1500 grams @ 500 meters per second
25,000 meters per second is the number we want, as that will not only allow the spacecraft pod to escape the planet, but that will put it within reach of the next speed barrier: the solar system’s escape velocity. Escaping a planet’s gravitational pull is easy in comparison to escaping the gravitational pull of a star, which exerts gravitational control over every object in that star’s solar system. Our spacecraft pod needs to be able to travel more quickly than Scadrial’s star and its orbiting bodies can pull it back. So if Scadrial’s star is like ours, which is likely since we see a yellow sun in The Alloy of Law, then the escape velocity for the Scadrial system is 45,000 meters per second.
We don’t actually have to achieve this speed if we aim our spacecraft pod well enough. A craft traveling 25,ooo meters per second can gain escape speed within the solar system by slingshotting around planets.
Unfortunately, achieving just that 25,000 meters-per-second speed push would take more Coinshots and Nicrobursts than probably exist or ever will exist on Scadrial. 4.32 million Coinshots paired with Nicrosil Nicrobursts would be required to boost 6.5 million grams up to a speed of 25,000 meters per second. Every man, woman, and child in Los Angeles could be a Coinshot or a Nicroburst and it still wouldn’t be enough people necessary to launch a spacecraft out of the solar system, let alone to velocities nearing the speed of light. It looks like there’s just no way to allomantically push a spacecraft to interstellar speeds.
But what if we figured out a really clever energy hack?
Well, we’d still be out of luck, because the necessity of having the propulsive force be Scadrial-bound means that the entirety of the propulsion from 0 meters per second to 25,000 meters per second has to occur in one large burst. That’s a lot of acceleration all at once, far far exceeding the horizontal human survival limit of 50 Gs. The G force would be so great that no amount of allomantic physical assistance would be able to make the passenger strong enough to withstand it. And even if they did, the craft itself wouldn’t.
What if we didn’t impart speed in one large burst, but by using several Coinshot acceleration points throughout the solar system?
This would mean that the inhabitants of Scadrial had already mastered manned spaceflight through their own solar system and could achieve speeds of 45-50 kilometers per second through allomantic or conventional means.
Let’s give the Scadrialians (Scadrialites? Scadriopedes?) the benefit of this doubt and say they’ve colonized their solar system and have installed strategic Coinshot acceleration points on planetary bodies (which would include moons and asteroids) throughout the system, each capable of upping the speed of the spacecraft by 50 km/s. Let’s say they’ve licked the acceleration problem, too, and the craft and occupant can survive the acceleration.
Unfortunately, we still can’t brute force useful interstellar space travel. The speed of light is 300,000 kilometers per second. Even half of that, 150,000 km/s, would take 3000 planetoid-based uber-Coinshot pushes. There’s not enough heavy matter in a solar system to provide that, even if you group uber-Coinshot pushes in large numbers on planetoids. You also run into a targeting problem once the spacecraft is going faster than 500 meters per second. Since Coinshots are human, they can only “push” as fast as they can detect the craft, and 500 meters per second is our upper physical reaction limit.
We’ve learned some important things, but in the end brute forcing a spaceship into the Cosmere at large won’t work. We’ll have to get trickier, which leads us to the next possible method.
Possible Method #2: Change your mass.
Iron Feruchemists, known as Skimmers, have a very interesting ability in that they can store away their own mass, making them extremely light and less dense. And mass is the biggest problem standing in the way of achieving faster-than-light speeds. Einstein said it himself when he whittled it all down to this famous equation:
What the equation means is that it would take this amount of energy to move this amount of mass at this speed. That speed is “c²,” which is the speed of light squared, which is 90 billion kilometers per second. If you have something with a mass (m) of 1 (i.e. anything) then you will need enough energy to accelerate that something to 90 billion kilometers per second. How to get that energy is another set of equations altogether, but as we learned by figuring out above how hard it is to get something to go just 50 kilometers per second, accelerating to 90 billion kilometers per second looks impossible.
Even if we decrease the mass of an object by half, so that it’s mass is now 0.5, we’d still need enough energy to accelerate it to 45 billion kilometers per second, which is still 150,000 times the actual speed of light, just to get it to travel at the speed of light! The speed of light is devilish like that. The only real way to “win” at this equation is to have something with no mass whatsoever, because then it takes no energy to travel the speed of light. This is, in essence, the definition of the speed of light. Light is the fastest thing in the universe, so it’s also the least massive thing in the universe.
Iron Feruchemists can decrease their mass, but as far as we know, a Feruchemist can’t decrease their mass from something to nothing. There would need to be a living being investing the iron metalmind with that living being’s mass, for one, so it would be impossible for that living being to make themselves completely without mass before dying from…lack of mass. We’ve seen characters in the Mistborn novels become sick from storing too much of their mass, so it seems quite possible that a Skimmer would kill themselves or decohere their own body before achieving zero mass.
There’s also the issue of where the mass goes once it is invested into the metalmind. Does the metalmind then become more massive as a result? Or is that mass stored elsewhere, perhaps outside the Physical realm, in the Cognitive or Spiritual realms? If the mass is simply transferred to the metalmind, then there’s no point to the Skimmer’s presence, the mass is still present on the person and/or in the spacecraft. If the mass “disappears,” though, then how do we reduce a person to zero mass in a way that they can be revived at their destination?
It would seem that this method is also a dead-end, but there’s an interesting theoretical possibility we haven’t considered: perception and negative mass.
Let’s look again at Einstein’s classic mass-energy equivalence: E=mc². The only way to win is to dial the variable “m,” for mass, from one down to zero. But what if you kept dialing? What if you can get “m” to be a negative number? Let’s see what happens when we dial past zero only slightly, and plug the number -.0000001 into the equation.
E = -.0000001 x 90,000,000,000
Now E = -90 units of energy! Not only does it now take no energy to move at the speed of light, but you’re producing excess energy that can be used to make you go even faster! SWEET DEAL.
The only problem is that you probably don’t exist anymore in conventional terms. And even if you did, traveling faster than light would still subject you to the vagaries of relativity, which states (roughly) that the faster you go, the more the passage of time slows for you. This means that what would be one second of instantaneous star-hopping for you would be 800 years (or something like that) for the people on Scadrial.
This may be a feature and not a bug for beings like Hoid. They may need large spans of time to pass on the worlds they visit in order to make large curatorial changes to societies. Hoid could visit the Knights Radiant on Roshar, zip off to Scadrial for some fun in the ash, then zip back to Roshar to pester Dalinar and Kaladin and institute step two of his plans. Thousands of years have passed for these worlds, but only a few months would have passed for Hoid.
How could someone like Hoid make himself a being of negative mass without dying? This is where perception plays a part. If we witnessed Hoid decreasing his mass entirely, it would appear to the observer as if he had died, getting clearer and clearer until he disappeared entirely. However, the universe itself would actively push an object of negative mass to speeds as fast as, or faster, than light. If someone like Hoid retained his self-awareness and ability to act while in a state of negative mass, then he wouldn’t die. His disappearance would merely be space pushing him away from our field of vision faster than we could detect.
How do we get a ship to do this?
Allomancers and Feruchemists would need to figure out a way to empower a machine to act with the same abilities granted to them by metals. Either this is impossible to do, or the world of Scadrial has not yet discovered the process for doing so. (Although there are hints that there are those on Scadrial who do know how to make simple allomantic machines, and that we may learn a lot more about it over the course of Shadows of Self and Bands of Mourning.)
Sanderson’s readers have seen inanimate objects become invested with consciousness in Warbreaker, via BioChroma Breath. This is very possibly a manipulation of Investiture: the force in the Cosmere capable of granting access to abilities like allomancy, Breath, or feruchemy. Little is known about the mechanics of Investiture, and this may be what Brandon Sanderson means when he says that readers will need to understand more about the Cosmere before being able to figure out how Mistborn abilities can be used to travel through space.
Tantalizingly, although we haven’t seen this in the books, the Ars Arcanum notes that Nicrosil Feruchemists can store Investiture and are known as “Soulbearers.” And if a Feruchemist can essentially store souls, then perhaps they can also grant a feruchemical soul to a machine?
You wouldn’t have to grant a soul to an entire spaceship, either.
Although a spaceship that was as lively as Nightblood the talking sword (from Warbreaker) would be AWESOME.
Even if we solve the problem of investing a machine with an allomantic or feruchemical ability, we still need to determine what to invest. Spaceships that need to ferry many people through the cosmos are BIG by necessity, and it might take a heck of a lot of Investiture to create one that could mechanically decrease its mass into a negative state. There’s also the issue of how to get the occupants of a spaceship into a state of negative mass. A feruchemical machine working on itself wouldn’t be able to include its passengers during a change of state in mass.
We also still have the problem of relativity to consider. For a faster-than-light vessel to be effective in the Cosmere, it would need to remain in the same frame of time as the planets that it visited, and simply building an Invested ship that can decrease its own mass won’t help in that regard. Centuries would still pass while the spaceship was traveling.
There’s a way we can solve both of these problems at once, though.
We need to make an Alcubierre Drive using Feruchemy.
In the 2000s, Mexican scientist Miguel Alcubierre used Einstein’s equations to figure out how you could trick the universe into pushing you faster than light using negative mass. Further, Alcubierre deduced a way to engineer a conventional spacecraft that could manipulate that negative mass.
It’s oddly simple. If you have material of negative mass (called “exotic matter” in theoretical physics) then all you need to do is spin it around and it will create a bubble in space that contracts the space in front of it and expands the space behind it. The bubble still consists of normal, unmoving, space with the spacecraft sitting in the middle of that. Utilizing an Alcubierre drive means that the spacecraft would never actually move in space, rather, it would sit inside this bubble of normal space while that bubble surfed the wave of expanding space behind it. Basically, it’s a warp drive.
Exotic matter is only theoretical for us, but what if a Feruchemist could Invest a machine with the ability to decrease the mass of an object into this exotic negative state? Build two of these, contain them, then spin them around a normal spaceship and Scadrial would have a functional, and downright comfortable, faster-than-light ship!
This method would require abilities that are currently conjecture in the Mistborn novels, but we’ve learned something very important, something that Mistings in the current western-themed Mistborn series could take advantage of right now.
Possible Method #3: Warping space by warping time.
The Alloy of Law introduced Cadmium and Bendalloy Mistings into the Mistborn universe, known as Pulsers and Sliders respectively, and boy oh boy are they important to this method!
A Cadmium-burning Pulser can make time slow down in a bubble around themselves, while a Bendalloy-burning Slider can make time speed up in a bubble around them. Pulsers are incredibly useful in day to day life—who hasn’t wanted more time in the day?—but Sliders may be the ones who hold the key to faster-than-light travel.
Time and space are intertwined aspects of each other. The most massive objects in the universe—our Sun, neutron stars, and black holes—warp space and time naturally by exerting massive amounts of gravitational force upon the space around them. Sliders and Pulsers, however, get to do this without having to summon enough power to crush a solar system. This is an extreme energy cheat on the part of these Mistings!
By altering the flow of time around them, Cadmium and Bendalloy Mistings are also altering the flow of space around them. Visualized, it looks like the effects an Alcubierre drive has on the fabric of space. (Pictured above.) According to the Ars Arcanum of the Mistborn series, Bendalloy Sliders contract time around them, speeding it to one-eighth of its normal rate, which means that they’re also contracting the space around them to one-eighth of its size. The occupants in that “space” travel at the same rate, but they have less “space” to cross, so the end result is that they arrive at their destination sooner. This also means that Cadmium Pulsers, by slowing time around themselves, are expanding the space around them, presumably to eight times its size. They are also traveling that “space” at the same rate, but there is now eight times more space to traverse before they arrive at their destination.
To an observer outside of these bubbles (in this case, the rest of the universe) a spaceship traveling through a Pulser’s bubble would appear to slow down within the bubble, while a spaceship traveling in a Slider’s bubble would appear to speed up.
Like Coinshots, Mistings who generate time-altering bubbles have certain limits. They are stationary and do not move with the Misting that generated them, and they’re small, on average five feet in diameter. To make a Slider’s spacetime-speeding bubble have any real effect, we’d need the bubble to be longer than the ship itself, so let’s figure out how big our ship is.
The length of a NASA shuttle orbiter is only 37 meters, but we’d most likely want a bigger ship (and a star to steer her by…) and a nice buffer of space before and after the ship itself, so we’d want a ship 50 meters passing through a bubble 150 meters in diameter. So far, a Slider bubble of this size has not been generated in the Mistborn books, but it’s possible one could be created with assistance from one or more Nicrosil Nicrobursts.
As we read above, minimum speed for a spaceship attempting to escape the gravitational pull of its own solar system is essentially 45,000 meters per second, but we’d actually want our spaceship to go slower than that. There are two reasons: One, in case something goes wrong with the Slider on board, the spaceship won’t be at risk of rocketing out of its solar system to certain doom. And two, the spaceship needs to be traveling slowly enough to be successfully captured by the gravity of its destination solar system.
As opposed to an Alcubierre drive, where the bubble travels with the spaceship, our ship has to move through a stationary bubble that does not travel with the ship. Our craft needs a precise speed, slow enough to achieve through conventional means but quick enough to take full advantage of the 150 meter bubbles.
Let’s set 25,000 meters per second as the speed a Scadrial spaceship would be traveling as it hits the first bubble generated by its onboard Slider/Nicroburst combo. (This is also roughly the speed of Earth’s quickest probes.) From the perspective of those inside the spaceship, their craft would traverse this distance in only .006 seconds. From the perspective of an outside observer (and space itself), the spaceship would travel through the bubble in only .000750 seconds, one-eighth of the time experienced by those inside the bubble.
The spaceship would emerge from the bubble 131.25 meters ahead of where it should be. .006 seconds is an instant for those onboard the spaceship, so the Slider/Nicroburst combo could generate and collapse bubbles as fast as they could think and jump the ship ahead 131.25 meters every time.
It would take 2,285,715 such bubbles to move the ship 1 light year, which is unfathomably exhausting for a Misting, but possible. (It is probably even more possible for a machine Invested with a Slider’s power.) If a bubble was generated once per second, it would only take 26 days and 11 hours to travel one light year, all while only traveling at a speed of 25,000 meters per second!
It gets even better, though. If two Slider/Nicroburst combos overlap their bubbles, then their warp effects are, at minimum, doubled. (We don’t know the actual multiplication factor, so let’s go with the minimum.) The ship would jump 140.625 meters in only one-sixteenth the time, more than halving the amount of time needed to move the ship one light year! A team of four Slider/Nicrobursts working in tandem would more than halve that number, making one light year a distance of only a week. If you keep doubling the number of Slider/Nicroburst combos, you keep halving the time. It doesn’t take long to get to an ideal combination of Sliders, Nicrobursts, and travel time, though. All in all, you would only need 32 Slider/Nicroburst combos to bring the distance of one light year down to a journey of a single day. Ideally, you would have twice that, so that you could have two alternating waves of Sliders and Nicrobursts that renew their stored metals while the other wave burned theirs. This isn’t at all an impossible task. In fact, it’s one that the people of Scadrial, as we know them from the current Mistborn Wax & Wayne series, are probably only one century away from achieving!
Possible Method #4: Read the 17th Shard.
I’m not the first, or best, person to think about how to achieve faster-than-light travel in Brandon Sanderson’s Mistborn series. The forums on 17th Shard hold even more theories, not just on FTL travel, but on a variety of aspects of Sanderson’s increasingly complex Cosmere. Dig in!