Powering Radiants off of Roshar

[Chiberty]

Although neither Radiants or Stormlight can get off of Roshar right now, I assume that problem will be solved eventually, so theory is about solving the next problem Radiants would run into after getting off-world: running out of Stormlight. If the Connection problem solved in this hypothetical future, the Radiant could, of course, take charged spheres with them, but away from the highstorms, what will they do when the spheres run out? Yes, there are perfect gems that will keep holding the Stormlight, but how much can a Radiant do with Light that they have to keep in a gem? Some of the things we've learned in RoW are key to solving this problem.

First, the Fused. They use Voidlight to control the Surges, but the Light, in many of of the Fused applications, does not run out. The shanay-im are able to fly around without expending any Voidlight. However, in the cosmere, we know that the amount of matter/energy/Investiture is conserved, so when a Heavenly One moves via flight, that energy has to come from somewhere.

Second, white sand. In Navani's experiments, she is able to use white sand to detect how fast a fabrial is using Light, and Moash is able to use it to detect a spren's location. As we know from the White Sand story (and Khriss's Taldain essay), when the sand is white, that means it is Invested. So, for the sand to turn white in the cases mentioned, that means it must absorb Investiture, and as we know, the glow from Stormlight is due to Investiture coming through the Spiritual Realm.

Quote

Alteroden

With Stormlight, the better the gem is cut, the less Stormlight it leaks, and the longer it holds its charge. If a gem was perfectly cut, on a molecular scale, would it leak Stormlight at all?

Brandon Sanderson

In a theoretical flawless gem, then no it would not.

Alteroden

Would it actually give off light?

Brandon Sanderson

[...] Theoretically no it would not, but it's not what you're thinking...

Alteroden

No no no, that’s not what I’m thinking, I figured that’s something totally different.

Brandon Sanderson

Well, actually, it probably would still give off light, because it's drawing out of the Spiritual Realm. So I’d say it still lights, but it doesn't leak. The leaking is not where the illumination is coming from. The illumination is coming from a direct... It's basically a light bulb screwed into the Spiritual Realm.

Shadows of Self Chicago signing (Oct. 12, 2015)

This explains how the sand is able to slowly charge even when just next to a spren - the spren, like Stormlight, emits Investiture from the Spiritual Realm. Now, here comes the more theory-based part. When Navani detects how fast fabrials use Light with the sand, I believe the sand is also simply absorbing this Spiritual radiation. When the fabrial uses Light, it tries to pull more power through it, causing more Investiture to be emitted.

Combining what we know about the Fused with this white sand detection information, I think that, in most cases, the Spiritual radiation is actually what is used up when someone uses Light as "fuel". The Light itself is not used up, it just leaks - and pulling Investiture through it faster makes it leak faster. This would also explain why the anti-Investiture explosions we see are not as big as one might expect - the Light that is annihilated is actually a relatively small amount of Investiture, at least in comparison to matter. It only seems like a large amount because large amounts of Investiture can be pulled through it. Now, one might point to spren becoming solid Blades as evidence against this disparity between energy levels in Investiture and in matter, but there is much we don't know about the conversion of Investiture to a solid state, and how exactly it differs from other states of Investiture (namely why raysium daggers don't react with anti-Voidlight), that I don't think that argument can hold much weight without more information.

That brings us to the idea - how Spiritual radiation being the true power behind Radiants will allow them to have extended use of their powers off of Roshar. A perfect gem charged with Stormlight is needed, along with a supply of white/black sand. If the charged gem is placed by/in the uncharged sand, the sand should slowly charge, while the gem remains full. Then, after accumulating a decent amount of charged sand (using more gems should make it faster), the Radiant can pour water on the sand, causing it to quickly release its Investiture. This should be the same Investiture that the Radiant would have used from the Light, only this allows them to release large amounts of the Investiture at once without having to draw the Light in.

White sand does fade over time, so this solution is not ideal, but since the perfect gems don't lose their charge, the sand doesn't need to hold the charge indefinitely - only long enough for the Radiant to accumulate a decent amount. It is possible that a similar solution using nicrosil Feruchemy would be more efficient, but we hardly know anything about how that works, so that is unclear.

Edited May 28, 2021 by Chiberty

[Frustration]

The only problem I'm seeing is that they might not be able to use the investiture from the sand, but Taldain is an important planet, and it's investiture uses are... underwhelming so this makes sense.

I came into this being skeptical but you have convinced me, good job.

[Honorless]

Wait a friggin minute, Raysium is solid Odium's Investiture but it didn't react with anti-Voidlight, his anti-Investiture and could be used to hold it, why didn't I notice this discrepancy!

Edited May 28, 2021 by Honorless

[GoWibble]

Essentially, you claim that the amount of "spiritual radiation" emitted across a gem's lifetime is more Investiture than a Radiant would gain if they simply breathed in the Light from the gemstone.

This process doesn't seem like it would be significantly net-positive for it to infuse other gems and sustain the process, at least on a small scale. This would need to happen on a massive scale to produce a significant net gain, and by that point, I wonder if there is not an easier way to do this. Especially on Sel.

I think this would work, it just might not be very effective.

Edited May 28, 2021 by GoWibble

[Chiberty]

45 minutes ago, GoWibble said:

Essentially, you claim that the amount of "spiritual radiation" emitted across a gem's lifetime is more Investiture than a Radiant would gain if they simply breathed in the Light from the gemstone.

This process doesn't seem like it would be significantly net-positive for it to infuse other gems and sustain the process, at least on a small scale. This would need to happen on a massive scale to produce a significant net gain, and by that point, I wonder if there is not an easier way to do this. Especially on Sel.

I think this would work, it just might not be very effective.

Oh, I'm not claiming that you'd get more than from breathing it in - just that you would get some. The reason for doing this instead of breathing it in is so you don't run out, even if does end up being inefficient, since the source sphere would not be depleted.

Edited May 28, 2021 by Chiberty

[ScadrianTank]

This is a cool idea, but it doesn't scale very well. By era 4, Radiants would have to travel throughout the whole cosmere without running out of Light. And spheres are just not going to cut it. They don't hold much Light relative to their size and are too easy to break. So they would need either a source of renewable Light nearby or something with a much larger capacity and Investiture-density. This might be where the whole purified/refined Investiture thing comes into play.

 

[apepi]

On 5/28/2021 at 0:19 AM, Honorless said:

Wait a friggin minute, Raysium is solid Odium's Investiture but it didn't react with anti-Voidlight, his anti-Investiture and could be used to hold it, why didn't I notice this discrepancy!

Yeah, I talked about this else where and the only thing I could come up with is metal is wierd... 

[GoWibble]

On 5/28/2021 at 9:21 AM, Chiberty said:

Oh, I'm not claiming that you'd get more than from breathing it in - just that you would get some. The reason for doing this instead of breathing it in is so you don't run out, even if does end up being inefficient, since the source sphere would not be depleted.

Just to be clear, are you claiming that the Investiture absorbed by the sand is or is not Investiture that is an 'excess' or more than what the sphere is holding and leaking?

[Chiberty]

3 hours ago, GoWibble said:

Just to be clear, are you claiming that the Investiture absorbed by the sand is or is not Investiture that is an 'excess' or more than what the sphere is holding and leaking?

I'm not claiming whether the sand holds less or more Investiture than the sphere. The rate at which the sand gains Investiture is related to the amount of Investiture in the sphere. The amount depends on a combination of the amount of sand, how long it has been there, and that rate.

[MGershone]

On 5/27/2021 at 10:59 PM, Chiberty said:

Combining what we know about the Fused with this white sand detection information, I think that, in most cases, the Spiritual radiation is actually what is used up when someone uses Light as "fuel". The Light itself is not used up, it just leaks.

If this is true, then what exactly is the Light? I've  always  assumed Light is Investiture, but if not, it's got to be something else.

 

On 5/28/2021 at 10:01 AM, ScadrianTank said:

And spheres are just not going to cut it.

(Unintentional hilarious Stormlight pun!) (Unless you meant to do that) (I can't tell)

[ScadrianTank]

27 minutes ago, MGershone said:

(Unintentional hilarious Stormlight pun!) (Unless you meant to do that) (I can't tell)

I really haven't, lol.

[Chiberty]

1 hour ago, MGershone said:

If this is true, then what exactly is the Light? I've  always  assumed Light is Investiture, but if not, it's got to be something else.

Under this theory, it's still Investiture, just not the Investiture that is used up. It just provides a pathway to get the fuel, like metals in allomancy do, except in this case, the thing providing the pathway is Investiture itself.

[MGershone]

27 minutes ago, Chiberty said:

Under this theory, it's still Investiture, just not the Investiture that is used up. It just provides a pathway to get the fuel, like metals in allomancy do, except in this case, the thing providing the pathway is Investiture itself.

So you're theorizing the existence of static Investiture that doesn't do anything, but just provides a connection between the Physical and Spiritual Realms?

[Chiberty]

2 hours ago, MGershone said:

So you're theorizing the existence of static Investiture that doesn't do anything, but just provides a connection between the Physical and Spiritual Realms?

I'm not saying that Light can't do anything else, just that in the case of surgebinding, that's what it does. (Also don't know that I'd call it static Investiture, but that's not part of this theory)

Edited May 30, 2021 by Chiberty

[GoWibble]

21 hours ago, Chiberty said:

I'm not claiming whether the sand holds less or more Investiture than the sphere. The rate at which the sand gains Investiture is related to the amount of Investiture in the sphere. The amount depends on a combination of the amount of sand, how long it has been there, and that rate.

What I'm getting caught up on is how this will help extend the life of the sphere or to let the Radiant use extra investiture. 

What I think that you are proposing is that the Sand will gather a significant amount of the investiture that is radiating from the sphere and that from there, the Radiant can pour water onto the sand and release the stored investiture. From there, the Radiant could possibly inhale the Investiture and conduct it back to the sphere (by hacking the magic to convert it back to Light) or use it. If they re-infuse the sphere, it will lengthen the life of Light in the sphere significantly. This seems to be what you are suggesting here:

On 5/28/2021 at 9:21 AM, Chiberty said:

Oh, I'm not claiming that you'd get more than from breathing it in - just that you would get some. The reason for doing this instead of breathing it in is so you don't run out, even if does end up being inefficient, since the source sphere would not be depleted.

This makes sense to me, and I see how it could be useful to keep infused spheres infused for longer amounts of time, but what you said here earlier threw me off:

On 5/27/2021 at 10:59 PM, Chiberty said:

A perfect gem charged with Stormlight is needed, along with a supply of white/black sand. If the charged gem is placed by/in the uncharged sand, the sand should slowly charge, while the gem remains full. Then, after accumulating a decent amount of charged sand (using more gems should make it faster), the Radiant can pour water on the sand, causing it to quickly release its Investiture. This should be the same Investiture that the Radiant would have used from the Light, only this allows them to release large amounts of the Investiture at once without having to draw the Light in.

If you require a perfect gemstone, then why do you need this process with the Sand to keep the gemstone infused? What benefit does releasing a large amount of investiture without having to draw the Light in have for the Radiant? This seems like a good way to convert kinds of Investiture to the kind that the Sand releases, but if you already need to hack the magic system to convert the Sand-type investiture (This made me think of Pokemon and the energy types for the different kind of Investiture ) to Light or to something else, then cutting out a step and directly hacking one type of Investiture to the kind that you need seems like it could be simpler. I feel like I'm missing the conclusion to your point.

[Chiberty]

5 hours ago, GoWibble said:

What I'm getting caught up on is how this will help extend the life of the sphere or to let the Radiant use extra investiture. 

I'm basically suggesting a way to allow a Radiant to use Light like a Fused. In most cases, a Fused does not run out of Light when surgebinding, since they perfectly contain it, and none leaks out.

A perfect gem is needed here because it acts as the perfect container, like a Fused. The sand is there to catch the Investiture radiating from the sphere so the Radiant can use it. In a normal case, where the Radiant intakes the Light, they can pull the "radiation" through it quickly, but here, it is just being emitted at the natural rate, which is why the Radiant needs to wait for a bunch of sand to charge before they can surgebind effectively.

So it's not extending the life of the sphere or letting the Radiant use extra Investiture - it just lets the Radiant surgebind without leaking any Light.

[lipat97]

I think RoW experiments with light point towards other sources of Stormlight in the future. Converting rhythms to light has been explored, a little further and we can see Navani creating stormlight generators. 
 

As for the Connections to Roshar, I think its clear that they can either by severed by Nightblood or transfered by a Bondsmith or potentially by Hemalurgy. Also potentially Duralumin Ferrings have some power with Connections.

[spaidapig]

I'm not sure if I agree with your idea or not, because it has some pretty valid points and I think you can fit many of the examples of Surgebinding/Farbrialtech in it, but only if certain conditions turn out to be true, which I am not sure about.

But first to your assumptions regarding the Sand:

On 28.5.2021 at 3:21 PM, Chiberty said:

Oh, I'm not claiming that you'd get more than from breathing it in - just that you would get some. The reason for doing this instead of breathing it in is so you don't run out, even if does end up being inefficient, since the source sphere would not be depleted.

On 30.5.2021 at 5:39 PM, Chiberty said:

I'm not claiming whether the sand holds less or more Investiture than the sphere. The rate at which the sand gains Investiture is related to the amount of Investiture in the sphere. The amount depends on a combination of the amount of sand, how long it has been there, and that rate.

Do we know for sure, that the Sand from Taldain can detect Fused or perfect gemstones?
So far as I understand it, the Sand is able to detect kinetic Investiture, ergo Investiture that is being used oder leaking from something (this can be an imperfect Gemor a Radiant holding Stormlight)
In this Scenario it could definitely not detect Stormlight in a perfect Gem.

If it can detect perfect Gemstones, by what you are calling Spiritual Radiation, this would mean, that the Radiant could get more Storlight from a combination of Sand an Gem, because the Gem doesn't lose anything, but the Sand still charges.
This process would create more Investiture by itself, without any outside force like a Perpendicularity or natural Investiture distribution like the Sun on Taldain or the Storms on Roshar.

 

On 30.5.2021 at 7:39 PM, Chiberty said:

Under this theory, it's still Investiture, just not the Investiture that is used up. It just provides a pathway to get the fuel, like metals in allomancy do, except in this case, the thing providing the pathway is Investiture itself.

So this means, that using a multiple lashing would be like flaring a metal, and by that it would be used up faster, am I right?

Another thing is the rate that Squires, Radiants from different Ideals and Honorbladewielders use Stormlight.
We know that Radiants are a lot more effective, but why is that so?
Do Squires and Honorblade work on Stormlight and progressing Radiants on the Spiritual Radiation provided by the former, which would be more effective?

You are mostly basing your theorie on this WOB:

On 28.5.2021 at 4:59 AM, Chiberty said:

Quote

Alteroden

With Stormlight, the better the gem is cut, the less Stormlight it leaks, and the longer it holds its charge. If a gem was perfectly cut, on a molecular scale, would it leak Stormlight at all?

Brandon Sanderson

In a theoretical flawless gem, then no it would not.

Alteroden

Would it actually give off light?

Brandon Sanderson

[...] Theoretically no it would not, but it's not what you're thinking...

Alteroden

No no no, that’s not what I’m thinking, I figured that’s something totally different.

Brandon Sanderson

Well, actually, it probably would still give off light, because it's drawing out of the Spiritual Realm. So I’d say it still lights, but it doesn't leak. The leaking is not where the illumination is coming from. The illumination is coming from a direct... It's basically a light bulb screwed into the Spiritual Realm.

Shadows of Self Chicago signing (Oct. 12, 2015)

 

Brandon says, that the leaking is not what is causing the Glow of the Spheres but that it is more like a lightbulb, that is screwed in the SR. If we take this by word, it only means, that investiture in Gemstones glows. But not that this radiation is made up of Investiture. I'm saying this, because Lightbulbs don't emmit the electricity they are powered with, but they glow as well.
I'm reading this more a current flowing from an infinit battery and the light in the gem is the wire that creates the glowing.
When SL leaks the wire gets thinner an thinner until there is no wire left to glow.

 

Even the Fused need Investiture supply, even if they are not leaking any Voidlight at all.
We have seen this on many occasions:
They use their Voidlight for healing from wounds and they get hit often enough they need to retreat from the fight.
They can Lash thing, like Windrunners do sometims, which costs them VL as well.
The Pursuer uses up his VL pretty frequently when creating new Bodies.
And I belive theis Soulcasters cannot Soulcast indefinitely.

Well, these are my ideas to your theory.

 

 

18 hours ago, lipat97 said:

I think RoW experiments with light point towards other sources of Stormlight in the future. Converting rhythms to light has been explored, a little further and we can see Navani creating stormlight generators. 
 

As for the Connections to Roshar, I think its clear that they can either by severed by Nightblood or transfered by a Bondsmith or potentially by Hemalurgy. Also potentially Duralumin Ferrings have some power with Connections.

But she would still need Investiture to start with.
Navani cannot create the Light with the Rythms, only attune certain Investiture to different tones, in this case the normal Tones and the Anti-Tones. But she cannot convert Investiture into another one.

But I think they are on a really good track to "invent" some kind of purified or distilled Investiture that is Connection-less, or has the full Connection to all Shards. Even though Brandon has said, that something like unconnected Investiture doesn't exist.

[lipat97]

I cant figure out how to reply/quote off here but is that really all Navani did? I was under the impression that her attuning towerlight with the sibling flooded the tower with light. Its gotta be more than just combining two investitures and repulsing some.
 

Maybe it is a bit much, because that would imply investiture can just be made anywhere with a good vessel and the right drum beat (and Intent). But it also makes sense that interacting with wave functions would allow some breaking through to the Spirit Realm... and clearly it already does to some degree with Singer’s agriculture. I also fully expect people in these series to get more OP, not less so Investiture generators sound like a perfectly reasonable tech development for decently advanced Cosmere civs. And I do think the reason he went so in depth with the Light and Rhythms in RoW is because Navani’s discoveries here are going to be the origin of that technology. Even if all she figured it out was how to create antilight and compound light, that still sounds like its on the path to figuring out how to create regular light and possible convert one kind of investiture to another. 
 

Actually I forget what they said about the Singer agriculture stuff. Did they sing the Song of Cultivation to use stormlight gems to help make crops? That sounds like a shift of investiture already

[spaidapig]

8 minutes ago, lipat97 said:

I cant figure out how to reply/quote off here but is that really all Navani did? I was under the impression that her attuning towerlight with the sibling flooded the tower with light. Its gotta be more than just combining two investitures and repulsing some.

Yeah, this is something that is solely possible for the Sibling and their Bondsmith. You see, Towerlight is the Essence the Sibling is made of, and as well THEIR Light. The only entity on Roshar who is able to create it, is the Sibling and their Radiant.
So you are right, that Navani basically turned into a Investiture generator.

But only they can use it. We don't even know in Navani can Surgebind with Towerlight or if it is just usable by the Silbling to Power Urithiru.

 

12 minutes ago, lipat97 said:

But it also makes sense that interacting with wave functions would allow some breaking through to the Spirit Realm... and clearly it already does to some degree with Singer’s agriculture.

I think, this is kind of an interaction from a Rosharan Rhythm, something like a Rhythm of Growth or similar.
But this som kind of natural interaction between SL and Music.

[lipat97]

Only they can use it? Didnt Kaladin get a boost when they turned on the tower? Anyway if they can combine two lights its reasonable to expect them to find a way to spit them apart. Maybe using antilight to “repel” the lifelight out of the towerlight? Although a bondsmith’s kinda a stormlight generator anyway and that doesn’t fix the Connection problem... actually, Bondsmiths do anyway right? Just move the connection stormlight has with roshar to something portable and you can move it through shadesmar. I wonder if Dalinar did his realm collapse thing in Scadrial if it’d still pump everyone with stormlight or if it’d just be the shardic power native to that planet.

I like the implications so far that every shard has its own rhythm, light, metal, etc but I think the first two are more than just catalysts. It looks like they determine the type of investiture rather than the other way around. I think Sanderson might be hinting at String Theory here where if you change the vibrations of something you change its nature. Like investiture IS the same thing with different vibrations. And who knows, if you combine all the shardic rhythms maybe you get adonalsoum or whatever its spelt. [talking about spelling, its a myrical I havent stormed up rhythm 15 different ways yet]

[spaidapig]

Quote

Only they can use it? Didnt Kaladin get a boost when they turned on the tower?

I was of the impression, that this was, because the Repressionfabrial that was powered by Raboniels Voidlight stopped working. 

Wasn't Urithiru described as boosting Radiant powers?

Although this could be a crossover effect from Towerlight.

Quote

 if they can combine two lights its reasonable to expect them to find a way to spit them apart. Maybe using antilight to “repel” the lifelight out of the towerlight? 

I like this a lot. Maybe we will see something like this in the series.

 

Quote

Just move the connection stormlight has with roshar to something portable and you can move it through shadesmar. I wonder if Dalinar did his realm collapse thing in Scadrial if it’d still pump everyone with stormlight or if it’d just be the shardic power native to that planet.

This should work. Connection is their power. And as we have seen from Ishar, you can do some crazy stuff with it.

As Investiture is pulled from the SR and in the SR every place is the same, Dalinar should definitely pull Stormlight. 

Allomancers can burn metal anywhere and will still be powered by Harmony. This comes from their Connection to the Shard. Should be no problem.

[+Harrycrapper]

5 hours ago, lipat97 said:

I cant figure out how to reply/quote off here but is that really all Navani did? I was under the impression that her attuning towerlight with the sibling flooded the tower with light. Its gotta be more than just combining two investitures and repulsing some.
 

Maybe it is a bit much, because that would imply investiture can just be made anywhere with a good vessel and the right drum beat (and Intent). But it also makes sense that interacting with wave functions would allow some breaking through to the Spirit Realm... and clearly it already does to some degree with Singer’s agriculture. I also fully expect people in these series to get more OP, not less so Investiture generators sound like a perfectly reasonable tech development for decently advanced Cosmere civs. And I do think the reason he went so in depth with the Light and Rhythms in RoW is because Navani’s discoveries here are going to be the origin of that technology. Even if all she figured it out was how to create antilight and compound light, that still sounds like its on the path to figuring out how to create regular light and possible convert one kind of investiture to another. 
 

Actually I forget what they said about the Singer agriculture stuff. Did they sing the Song of Cultivation to use stormlight gems to help make crops? That sounds like a shift of investiture already

I think Navani and the Fused access their respective Investitures similar to how Allomancy works. In Allomancy, the metals themselves don't have power, they are a pattern to receive Investiture for a specific purpose. Fused(and I think Regals) sing the song of prayer and they are Invested with Voidlight. Navani and the Sibling together sang two separate songs in harmony to access Towerlight. The song, like the metals, is a pattern or an access key that allows them to infuse themselves with the respective Investiture for that song. But I think there's something else in there that determines which types of Investiture someone has the ability to infuse. For example, Kaladin can't use Voidlight to fuel his Surges via his Bond with Syl, but Renarin likely can use Voidlight to fuel his Surges. So, I don't think gaining access to other types of Investiture is as simple as learning the Rhythm of that Shard, though it would allow you to manipulate Investiture that you already have stored on hand. It's why Raboniel didn't have unlimited access to Lifelight for Navani to experiment with, she couldn't just conjure it up. 

As to why it Navani's revival of the Tower was so dramatic, I believe the limits of the amount of Investiture you can produce using that method are based on the vessel's capacity. In the case of the Fused, they are limited to how much they can hold in themselves and their gemheart much like a Radiant is limited by how much they can hold in themselves and what gems they have on them when Dalinar opens the perpendicularity. The Sibling is a massive network of fabrials and gemstones, which means they can hold a massive amount of light, so they drew in a massive amount when they were finally able. 

On 5/27/2021 at 7:59 PM, Chiberty said:

That brings us to the idea - how Spiritual radiation being the true power behind Radiants will allow them to have extended use of their powers off of Roshar. A perfect gem charged with Stormlight is needed, along with a supply of white/black sand. If the charged gem is placed by/in the uncharged sand, the sand should slowly charge, while the gem remains full. Then, after accumulating a decent amount of charged sand (using more gems should make it faster), the Radiant can pour water on the sand, causing it to quickly release its Investiture. This should be the same Investiture that the Radiant would have used from the Light, only this allows them to release large amounts of the Investiture at once without having to draw the Light in.

The only way I see this theory working is if light stored in a gemstone is its own mini perpendicularity and the sand is piggybacking on the stored Investiture to access the Spiritual Realm. You can't have an end positive amount of Investiture by letting it leak into the white sand unless that Investiture is coming from something/somewhere else. Extrapolating on the lightbulb analogy, there wouldn't be enough energy radiating from a lightbulb to power a separate lightbulb, but you might be able to connect to the source of the lightbulbs power and syphon off some for other purposes.  A relevant question for Brandon would be whether or not an infused perfect gemstone would charge the sand, as we don't know that for a fact and this theory is predicated on that assumption. 

[Chiberty]

7 hours ago, spaidapig said:

I'm not sure if I agree with your idea or not, because it has some pretty valid points and I think you can fit many of the examples of Surgebinding/Farbrialtech in it, but only if certain conditions turn out to be true, which I am not sure about.

But first to your assumptions regarding the Sand:

Do we know for sure, that the Sand from Taldain can detect Fused or perfect gemstones?
So far as I understand it, the Sand is able to detect kinetic Investiture, ergo Investiture that is being used oder leaking from something (this can be an imperfect Gemor a Radiant holding Stormlight)
In this Scenario it could definitely not detect Stormlight in a perfect Gem.

If it can detect perfect Gemstones, by what you are calling Spiritual Radiation, this would mean, that the Radiant could get more Storlight from a combination of Sand an Gem, because the Gem doesn't lose anything, but the Sand still charges.
This process would create more Investiture by itself, without any outside force like a Perpendicularity or natural Investiture distribution like the Sun on Taldain or the Storms on Roshar.

So this means, that using a multiple lashing would be like flaring a metal, and by that it would be used up faster, am I right?

Another thing is the rate that Squires, Radiants from different Ideals and Honorbladewielders use Stormlight.
We know that Radiants are a lot more effective, but why is that so?
Do Squires and Honorblade work on Stormlight and progressing Radiants on the Spiritual Radiation provided by the former, which would be more effective?

You are mostly basing your theorie on this WOB:

Brandon says, that the leaking is not what is causing the Glow of the Spheres but that it is more like a lightbulb, that is screwed in the SR. If we take this by word, it only means, that investiture in Gemstones glows. But not that this radiation is made up of Investiture. I'm saying this, because Lightbulbs don't emmit the electricity they are powered with, but they glow as well.
I'm reading this more a current flowing from an infinit battery and the light in the gem is the wire that creates the glowing.
When SL leaks the wire gets thinner an thinner until there is no wire left to glow.

 

Even the Fused need Investiture supply, even if they are not leaking any Voidlight at all.
We have seen this on many occasions:
They use their Voidlight for healing from wounds and they get hit often enough they need to retreat from the fight.
They can Lash thing, like Windrunners do sometims, which costs them VL as well.
The Pursuer uses up his VL pretty frequently when creating new Bodies.
And I belive theis Soulcasters cannot Soulcast indefinitely.

Well, these are my ideas to your theory.

We don't know for sure if the sand can detect an infused perfect gem, but there is some evidence that shows it could be possible, which I put in my post. One piece of evidence is that the Fused can do some surgebinding indefinitely. And yes, as you point out, for some things, the Fused do use up Voidlight, but the fact that they are able to do just some things without using it up is key. For the shanay-im to fly about, they must be getting energy from somewhere, and if they can do this without expending Light, then the Light itself cannot be the energy source in that scenario. I am suggesting that this unknown energy source is the Spiritual Realm, facilitated via the Light. Another bit of evidence for the "Spiritual radiation" is the sand's ability to detect spren. Unless spren are constantly losing the Investiture they are composed of, it seems that some other Investiture must be emanating from them.

As you said, this being true would allow the Radiant to get more Investiture than would usually be possible, by pulling from the Spiritual Realm. However, this is not unheard of in other uses. Again, the shanay-im are able to get more energy without using Light, and in the metallic arts, iron feruchemy could be used to generate energy without using up the stored attribute (tapping weight at the top of a wheel, and storing at the bottom, thus spinning the wheel). 

27 minutes ago, Harrycrapper said:

The only way I see this theory working is if light stored in a gemstone is its own mini perpendicularity and the sand is piggybacking on the stored Investiture to access the Spiritual Realm. You can't have an end positive amount of Investiture by letting it leak into the white sand unless that Investiture is coming from something/somewhere else. Extrapolating on the lightbulb analogy, there wouldn't be enough energy radiating from a lightbulb to power a separate lightbulb, but you might be able to connect to the source of the lightbulbs power and syphon off some for other purposes.  A relevant question for Brandon would be whether or not an infused perfect gemstone would charge the sand, as we don't know that for a fact and this theory is predicated on that assumption. 

Yep, that's pretty much exactly how I'm trying to suggest this would work. I don't know if the Light would count as a mini perpendicularity here, since a perpendicularity connects to the Cognitive Realm as well (which the Light may or may not do), but I do think it's at least similar to a perpendicularity's connection to the Spiritual Realm.

[lipat97]

1 hour ago, Harrycrapper said:

I think Navani and the Fused access their respective Investitures similar to how Allomancy works. In Allomancy, the metals themselves don't have power, they are a pattern to receive Investiture for a specific purpose. Fused(and I think Regals) sing the song of prayer and they are Invested with Voidlight. Navani and the Sibling together sang two separate songs in harmony to access Towerlight. The song, like the metals, is a pattern or an access key that allows them to infuse themselves with the respective Investiture for that song. But I think there's something else in there that determines which types of Investiture someone has the ability to infuse. For example, Kaladin can't use Voidlight to fuel his Surges via his Bond with Syl, but Renarin likely can use Voidlight to fuel his Surges. So, I don't think gaining access to other types of Investiture is as simple as learning the Rhythm of that Shard, though it would allow you to manipulate Investiture that you already have stored on hand. It's why Raboniel didn't have unlimited access to Lifelight for Navani to experiment with, she couldn't just conjure it up. 

As to why it Navani's revival of the Tower was so dramatic, I believe the limits of the amount of Investiture you can produce using that method are based on the vessel's capacity. In the case of the Fused, they are limited to how much they can hold in themselves and their gemheart much like a Radiant is limited by how much they can hold in themselves and what gems they have on them when Dalinar opens the perpendicularity. The Sibling is a massive network of fabrials and gemstones, which means they can hold a massive amount of light, so they drew in a massive amount when they were finally able. 

The only way I see this theory working is if light stored in a gemstone is its own mini perpendicularity and the sand is piggybacking on the stored Investiture to access the Spiritual Realm. You can't have an end positive amount of Investiture by letting it leak into the white sand unless that Investiture is coming from something/somewhere else. Extrapolating on the lightbulb analogy, there wouldn't be enough energy radiating from a lightbulb to power a separate lightbulb, but you might be able to connect to the source of the lightbulbs power and syphon off some for other purposes.  A relevant question for Brandon would be whether or not an infused perfect gemstone would charge the sand, as we don't know that for a fact and this theory is predicated on that assumption. 

Ok but if you’re saying a rhythm is like metal then that means they work universally... thats already a way to get stormlight off Roshar, and a rhythm is much easier to transport and reproduce than a metal is. If “producing” investiture just means finding patterns that transfer investiture from the SR to the PR, and a rhythm is one of those patterns, then there’s no reason we cant eventually have fabrials produce powering radiants, fused or allomancers. You just need someone to sing the rhythm and maybe have a big enough vessel - thats perfectly doable. Even if that just means they can get a factory that recharges spheres, thats really good and is not restricted from being off-world. I think this can be a major solution to intersystem warfare by finally allowing powers to transfer across shadesmar, even if they take some setup. There’s also ofc the question to whether these factories/fabrials would even work the same way in shadesmar, so you might actually need a foothold on the PR planet before you can set up logistical support for your superpowered warriors 
 

also, can someone remind me when they brought up the fact that spheres couldn’t be brought outside their system? Im like pretty sure some of this info was available in book 3 (or at least Arcanum Unbounded) but Im trying to be careful in case its actually a book 4 spoiler