Rosharan Divers?

[SeekingShards]

For the specifics for fabrials I am drawing from the Cosmere RPG Stormlight Handbook which might not be totally accurate to make the game fun but is the closest approximation I know of. Under the rules text for the Attractor and Repeller fabrials it specifies that it can attract or repel a particular Essence or material. If a character has a Repeller attuned to water and an Attractor attuned to air could a character possibly walk underwater on dry land with the Attractor pulling breathable air from the surrounding water? My first concern is if a repeller would be strong enough to push away water at any substantial depth. The rules text says it pushes away the attuned material weakly. But it also says “If the repeller is heavier, it pushes the attuned material away from it at a rate of 1 foot per round [Approximately 10 seconds].” Does that mean the Repeller’s weight is directly proportional to the depth it could effectively repel the water. As well when it says push “the attuned material” does that just mean the material in the radius. Also with it only pushing 1 foot per every 10 seconds that isn’t enough to overcome gravity as gravity accelerates material towards the earth at 9.8 meters per second. Even with Roshar’s diminished size it would still overpower the repeller. But if we assume it could repel the water with enough force to create a a pocket of air, whether by strengthening the fabrial or by ignoring gravity, would the attractor be able to attract a sufficient amount if any air? We know spren and the cognitive realm work by perception so would it only be able to attract air that is perceived as air? Would it only be able to attract already breathable air or would it be able to separate the air from water? Would you also need a repeller for the carbon dioxide you exhale? 

Edited January 5 by SeekingShards
Needed to site where I got the specific abilities of the fabrials

[Schizoposting]

I don't have access to the Cosmere RPG, but I think that your design is impractical, because of physical and practical constraints. There is on average less than 10 milligrams of oxygen per liter of seawater. Supposing that a person needs about 250 milligrams of oxygen per minute to survive*, then the device would have to process a minimum of 25 liters of sea water per minute, assuming an efficiency of 100%. 

Even if this were possible, it would likely be so difficult and energy expensive, that it would be much easier to just build a regular diving suit, or a submarine. So, I don't think that your device makes sense.

*This is just a rough estimate, but the real value should be somewhere in that ballpark

[SeekingShards]

I think that a diving suit or a submarine would be more reliable but not easier. Just for the fact that as this would likely be a privately funded operation and would not be out of necessity but out of curiosity that no supporting infrastructure would emerge with much urgency. Just like the Wright brothers or the actual history of submarines they were invented out of dreams and curiosity not out of necessity leaving them to take years(and in the case of submarines around 200 years) to be truly useful and viable in any manner. And when there is not a push to invent due to necessity, invention doesn’t come from the discovery of new technologies but out of creative application of old methods. So my real question is could a rich Rosharan scientist feasibly create the magical proto-diving “suit.” I agree it might not be the most efficient but it would be the most accessible as the technology already exists. That is more of a clarification of the question, not is this the best method but is it viable.

Also more on the point of science even if the Attractor had to sift through 25 liters of water it attracts in a sphere so assuming you are walking on the ocean floor so only about half of the sphere has usable air. Assuming the repeller is repelling water in a 6 foot radius which would likely need to be bigger and that the attractor is attracting in a 10 foot radius, the attractor would still have access to roughly 45,000 liters of water. Also on the point of it being energy intensive, it would 100% be energy intensive. But with the energy for fabrials literally coming from the sky and with the ability to recharge fabrials with infused spheres and a tuning fork or using unencased gems you could bring more energy to utilize. You could be right that it still just takes too much energy as all it says in the rules for the repeller and attractor is that when creating the fabrial you can set the radius of affect, but it doesn’t set an upper bound on it. This means I could be grossly overestimating the capability of these fabrials but I don’t know. Anyway at least with the Cosmere RPG it says for both the repeller and attractor that standard ones have 5 charges and expend 1 charge per hour they are active so already they have a 5 hour time limit and I would assume under intensive conditions such as this they would likely expend charges much quicker but even assuming they work at one half or even one fifth of normal efficiency, that is 1-2.5 hours. Which like I stated isn’t the best or most efficient but could be a big deal for the curious and rich Rosharans.

Like I said the biggest thing is not finding better or equivalently viable ways to go diving than modern earth has with Rosharan fabrials, but seeing if a current (by book 5) Rosharan could invent a way to spend extended periods of time underwater, without needing to be radiant or the such. So that is why I focused more if the fabrials themselves would have the capacity and capability to fulfill the inane plan I posed. At least currently think the biggest question of viability is whether the repeller can overcome the force of gravity, as the entire viability is based on the capability to create a bubble of dry land. As well it says if the material it is pushing is heavier than the fabrial itself, the fabrial will be pushed not the material. How would this apply to a liquid and with aspects like water pressure and the perception of the ocean itself. Would you treat the “material” as the entire object as it is perceived, such as the ocean or just the portion in the radius of effect. I assume this would apply to solids and fluids differently as to me it doesn’t make sense to only look at the portion in the radius(for solids) because if only a small section of the object was in the radius then regardless of weight(with rules as written) that if as long as that section is lighter than the fabrial, the object will be moved.

You could be right that just creating a fabrial powered diving suit or submarine would be easier but I don’t know how the two function with enough depth to understand the ways a fabrial could aid in there function or replace an mechanical part that they wouldn’t have access to.

What do you think? I could have misrepresented your points and if so I apologize, but I am just pondering viability and want to look at all of the aspects of the physics and interactions with said physics. As well I might be putting too much credence in the rules of the Cosmere RPG, that while cannon has many things simplified and some parts for fun and simplicity are stated with minimal nuance as in most scenarios that much detail just isn’t necessary.

[Schizoposting]

@SeekingShards I am not an engineer or a physicist, but I think that there quite a few issues with your idea:

Firstly, creating a bubble of air would be problematic because it would rise to the surface due to it having a lower density than the surrounding seawater, resulting in most of the oxygen being wasted. More realistically, you'd probably want to simply filter out the oxygen without actually trying to create a bubble around yourself. 

Secondly, since the oxygen is dissolved in the seawater, the force applied on said sea water should also be imparted on the oxygen, which would negate the repelling, at least to some extent. I actually think that it would be better to get rid of the water repeller altogether, and to simply attract oxygen instead. 

Thirdly, while you're right that there is plausibly enough water to supply the oxygen, actually extracting it at a usable level will require a massive amount energy, orders of magnitude stronger than the strongest fabrials that we've seen so far. This will also probably result in some very turbulent currents. 

Fourthly, you would need a way to collect all the oxygen that you've extracted so that you can breathe it in, without allowing it to escape. 

Finally, as I've already said, it's just easier to use more conventional designs; the optimal form of your idea would involve having some contraption that would suck in huge amounts of water, extract the oxygen, send it to the diver through a tube like the ones used in diving suites, and then eject the processed oxygen-poor water. But again, this would be so impractical, that it would be much easier to just make a regular diving suite. 

[Nitpicking]

If Cosmere axions work like our-universe atoms and molecules, you would have a hard time moving the oxygen molecules through the water while pushing the water away at the same time, since it would happen on a molecular basis, but fabrials are Cognitive devices (powered by Cognitive entities, spren) and would work on water as a whole, not on water and its constituents separately.

In my opinion.

[Jult]

A simpler option would probably be to rely on Soulcasting fabrials instead of attractor fabrials. As others have already pointed out, there won't be enough oxygen in the water to pull in. But you could Soulcast the water into breathable air. You'd still probably need a tank and/or suit of some kind to hold the air for you. So, in my opinion, you would probably want to build a relatively normal air tank you can "re-load" by filling it with water and Soulcasting the contents.

This probably opens the door to questions about keeping the tank at a safe pressure and whatnot, but maybe that's where modern Fabrial comes into play?

 

Or if your main interest is in diving and not fabrials: Shardplate. Shardplate would make an excellent diving suit. Though you'd probably still want some sort of gravity fabrials for mobility in the water. 

It's still in its spoiler period but in Isles of the Emberdark we see:

Spoiler

A Shardplate-based space suit. Which would probably be very similar.

And, in The Sunlit Man chapter 47, it's mentioned that Shardplate can "maintain temperature and life support". Unclear if that means Shardplate can maintain an air supply on its own somehow.. But I'm not really sure what else 'life support' could mean here.

[Duxredux he/him]

The idea of using active pumping via fabrial poses non-trivial energy requirements. Scuba divers don't have to carry the aparatus that extracts and compresses the air, they just carry the ready-to-use tank - all the work is done where atmosphere is abundant. A submarine gets around this in two ways - one being big enough to carry its own generator, and second by not extracting dissolved oxygen from local water. Submarines get oxygen by splitting the H2O and harvesting the oxygen from the water molecules themselves via electrolysisr. Basically from an energy stand point, relying on a fabrial to actively pull dissolved air out of water and actively hold it will be more energy intensive than conventional methodology. Either go with a fabrial sub or compress the air on land. Trying to do a man-powered dive with what is essentially a battery-operated air extractor that has to maintain pressure through actively applied Stormlight rather than putting it into a rigid metal container... that's just all sorts of inefficient. 

If we want to get slightly more into the weeds, the current setup also doesn't address technical challenges that divers have to face when 40+ meters. Recreational freediving instructors are required to be able to go 40 m down (i.e. just by holding their breath), so I figure your fabrial needs to beat "just hold my breath and have good training".

 

Spoiler

 Let's just start with saying that gas pressure when diving doesn't look particularly intuitive to me at first glance, considering this article: https://pmc.ncbi.nlm.nih.gov/articles/PMC1114047/. I'll try to simplify some of the concept that I found while poking around. First off, the earth human is used to breathing the usual atmosphere of 78% nitrogen, 21% oxygen, and 1% misc. Too little oxygen and obviously we pass out, but too much and the oxygen actually becomes toxic. Now what matters here is less the gas percentages in the air, but the oxygen molecule count expected per breath. Imagine you are in an air-tight room at the usual atmospheric pressure of 1 atm that gets compressed in half. Pressure doubles to 2 atm, and while the percentage of oxygen remains the same, the count of oxygen molecules that fit into a single breath has doubled. In a 2 atm environment, the oxygen percentage would probably need to be closer to 10.5% oxygen to be equivalent to regular atmosphere. This is further complicated because at higher pressures, nitrogen becomes a narcotic - actually this is what scuba divers run into first before oxygen toxicity when using basic air. The concept here is Dalton's Law with the term partial pressure if anyone else wants a deep dive (the pun just wrote itself).

So why do we care about the gas proportions as they change with pressure? Because as you dive the pressure of the air you breath needs to be close to the ambient pressure for lungs to function properly. In other words, as you dive deeper and deeper, the pressure of the air you breathe needs to rise to match the depth but the total percentage of oxygen required will decrease. Scuba manages this with a regulator. What you fill the rest of that percentage with is pretty important. The internet says divers using regular air hit nitrogen narcosis issues in the ballpark of 30-40 meters. A fabrial that just pulls oxygen will run into oxygen toxicity. A fabrial that just pulls air will not regulate gas percentages - you just get what's local. Deep divers intentionally take gas mixtures that don't work at shallower depths and instead for the depth and pressures they expect to be working at. The most expensive option from what I've seen swaps out nitrogen with inert helium to avoid narcosis with very surprisingly low oxygen percentages. Another method to deal with increasing pressure as the diver descends is a rebreather that scrubs out carbon dioxide and carefully reintroduces oxygen (depending on the system - the most high end version uses sensors to manage the partial pressure requirements to set the oxygen to a setpoint). A naive "just pull air or oxygen to me" ignores these issues. Submarines skip this issue by maintaining contant cabin pressure of around 1 atm.

Again, not saying that artefabrians can't solve this - just that it's not simple and doesn't address energy consumption requirements.

Edited January 7 by Duxredux

[DrPhysics he/him]

On 1/4/2026 at 11:02 PM, SeekingShards said:

My first concern is if a repeller would be strong enough to push away water at any substantial depth. The rules text says it pushes away the attuned material weakly. But it also says “If the repeller is heavier, it pushes the attuned material away from it at a rate of 1 foot per round [Approximately 10 seconds].”

Physicist here. This rule works well for an RPG since it is simple to calculate and follow, but it doesn't work as a way to estimate force because the object moves at a constant speed, which just means that all of the resistive forces (like friction) balance out with the force from the attractor, giving a total force of zero. And calculating all of the resistive forces would be a nightmare for something like water. (Is it flowing across the ground? Is it in a sliding bucket? If so, what is the bucket made out of? etc.)

Everything we've seen in the books so far makes it looks like attractors work by exerting a long-range pulling force like gravity or static electricity, just attuned to a single substance. In Words of Radiance, we see one draw water out of the air, and another that collects smoke from a fire.

In a fluid, that would result in a small, pressure-like force. Pulling water out of air is easy, because air is just a loose collection of molecules. Pull on the water a little bit, it will just drift towards the attractor without having much impact on the air around it (you'd see a little bit of air drug along through collisions, but not enough that you'd expect to be able to feel a wind). Pulling air out of water is much harder because the air is actually dissolved in the water, and there are intermolecular forces bonding (albeit weakly) to the water molecules, so if you start dragging the air out, you also exert a significant force on the water, pulling it in with the air.

 

Using a repeller to create a pocket of air around you is incredibly difficult. Because fluids can rearrange themselves, if you create a bubble around yourself under water, you don't just have to push away the water immediately around you; you have to push away hard enough to lift all of the water above you as well. (Think about trying to lift a stack of books. Technically, you only puch on the bottom book, but that push has to be strong enough to lift the rest of the books in the stack too.) To put that into perspective, if you have a repeller attuned to air that can push hard enough to create a perfect vacuum around itself (which is much stronger than anything we see in the books), and you changed it so it could push water just as hard, your bubble would completely collapse by the time you reached 10 m below the surface. Water is very, very heavy.