Surge of Tension: One Possibility

[Guest Parallax]

Based on an Arcanum posting by @PeterAhlstrom we know that the Stormfather's conversation with Dalinar about surges he can use was a mistake and it will be corrected in future editions. We also know that the surge of cohesion manipulates intermolecular forces allowing the user to "shape" objects. But still nobody has explained what tension does.

Here is my candidate, someone using the surge of tension is able to manipulate the modulus of elasticity. A solid put under pressure will deform, you can plot the amount deformation for a given amount of pressure and arrive at what is known as the stress-strain curve. For almost all matter the stress-strain curve is initially linear, its slope is called the modulus of elasticity (denoted by E). In other words E tells you how much force per unit of area you need in order to cause a fixed amount of change (we are making a bunch of simplifying assumptions inclulding everything happening along a single axis as depicted in the picture from Wikipedia):

The higher the slope the more rigid the solid (you need much greater force to induce the same amount of deformation). So here is how the surge of tension works: it temporarily increases the modulus of elasticity (makes the curve steeper) making the solid more rigid. A few caveats:

1. Higher modulus of elasticity is not the same as tougher. Increase it too much and you will get something too brittle that easily shatters (glass is very rigid). So properly using this surge is an optimization problem, the goal being to maximize the total energy the material can absorb (which is represented by the area under the curve).

2. This only applies to solids and not fluids or gases. In fact manipulating the surface tension of a fluid would fall under cohesion.

3. I really have no idea how this is "strong axial interconnection" whereas cohesion is "soft axial interconnection". 

PS: Here is the Wikipedia article I took the picture from: https://en.wikipedia.org/wiki/Stress–strain_curve

Edited October 4, 2019 by Parallax

[Aon Tia]

I think tension has been described in a wob as something like you take a piece of cloth and make it rigid

it seems to go with your discussion above

[+Oltux72]

13 hours ago, Parallax said:

Based on an Arcanum posting by @PeterAhlstrom we know that the Stormfather's conversation with Dalinar about surges he can use was a mistake and it will be corrected in future editions. We also know that the surge of cohesion manipulates intermolecular forces allowing the user to "shape" objects. But still nobody has explained what tension does.

Here is my candidate, someone using the surge of tension is able to manipulate the modulus of elasticity. A solid put under pressure will deform, you can plot the amount deformation for a given amount of pressure and arrive at what is known as the stress-strain curve. For almost all matter the stress-strain curve is initially linear, its slope is called the modulus of elasticity (denoted by E). In other words E tells you how much force per unit of area you need in order to cause a fixed amount of change (we are making a bunch of simplifying assumptions inclulding everything happening along a single axis as depicted in the picture from Wikipedia):

The higher the slope the more rigid the solid (you need much greater force to induce the same amount of deformation). So here is how the surge of tension works: it temporarily increases the modulus of elasticity (makes the curve steeper) making the solid more rigid. A few caveats:

Very well, then the elephant in the room: Can you make it negative? This may seem a stupid question, but if you can it looks to me like you have a material that will move against external pressures, which under gravity and in air, means more or less that it can deform elastically at will.

(Nalthis)

Spoiler

In fact, that looks quite like what Awakeners do when they make stuff move or change shape)

 

[Pagerunner]

I've collected all the WoBs on Tension in another thread:

Since it's the one we have the least information on, there isn't too much to prove or disprove any proposed mechanism.

A common theme for all the Surges is that they are more complex than a simple physical principle. Gravitation can affect a single gravitational relationship between two objects (person and planet) or all gravitational relationships of a single object (pulling all the arrows to impact a shield). Division can be unnaturally exothermic (making stone burn) or endothermic (making wood turn straight to ash). Cohesion, as I demonstrate in my thread, is especially bad, requiring several 'secondary powers' to function as we see it on-screen.

So, we'll need to see exactly how Tension plays out once it it makes it to the books, and how many different mechanisms it would require for all its effects. It's certainly possible that sometimes, it would behave like modifying the stress/strain curve. But I don't think that would necessarily disqualify Tension from working on a liquid; the Surge would just operate on an entirely different under those situations.

[Guest Parallax]

@The traveller that was my starting point.

@Oltux72 If the modulus of elasticity is negative then you need to apply constant pressure to keep the object from expanding. I don't see the connection to Nalthis, the surge of tension is passive relative to what happens there. 

@Pagerunner A very small correction: if a substance is made of one element it doesn't mean it has no molecule. But there are many substances that don't have a well-defined molecule (metals are perhaps a more common example than diamonds). 

[+Oltux72]

4 minutes ago, Parallax said:

 

@Oltux72 If the modulus of elasticity is negative then you need to apply constant pressure to keep the object from expanding. I don't see the connection to Nalthis, the surge of tension is passive relative to what happens there.

If you see elasticy as a constant of material. Which it usually is. For a monocrystalline material for example it is not; it depends on direction. You would need to use vectors to fully describe an object. If you have full control about these vectors, you should be able to make an object deform within the limits of elastic deformation. In other words, it moves.

[Guest Parallax]

On 10/6/2019 at 4:52 AM, Oltux72 said:

If you see elasticy as a constant of material. Which it usually is. For a monocrystalline material for example it is not; it depends on direction. You would need to use vectors to fully describe an object. If you have full control about these vectors, you should be able to make an object deform within the limits of elastic deformation. In other words, it moves.

First I would say that yes the modulus elasticity would depend on direction and that is something the surgebinder should manage. But then this is very different from Nalthis, the surgebinder needs to micromanage every single movement an object to achieve a goal in other words they have to do all the physical calculations themselves. There are no high level commands like they are in Nalthis. 

@Pagerunner I was thinking about the surge of division, couldn't you define it as the surge that increase entropy within a bounded physical space? The amount of investiture consumed would depend on the change in entropy times the volume within which it was increased.

[+Oltux72]

2 hours ago, Parallax said:

First I would say that yes the modulus elasticity would depend on direction and that is something the surgebinder should manage. But then this is very different from Nalthis, the surgebinder needs to micromanage every single movement an object to achieve a goal in other words they have to do all the physical calculations themselves. There are no high level commands like they are in Nalthis.

Other Surgebinders have shown a level of control that seems incompatible with needing to handle every detail, namely Malata burning the symbol into the table and Shallan showing every single hair.

2 hours ago, Parallax said:

  I was thinking about the surge of division, couldn't you define it as the surge that increase entropy within a bounded physical space? The amount of investiture consumed would depend on the change in entropy times the volume within which it was increased.

If you, for example, burn a piece of metal, you'll decrease entropy. Surely entropy would allow you to turn everything into unbound atoms. But they can also burn stuff. Now this may be a subsequent reaction with atmospheric oxygen, but it may not.

[Guest Parallax]

On 10/11/2019 at 0:00 AM, Oltux72 said:

Other Surgebinders have shown a level of control that seems incompatible with needing to handle every detail, namely Malata burning the symbol into the table and Shallan showing every single hair.

If you, for example, burn a piece of metal, you'll decrease entropy. Surely entropy would allow you to turn everything into unbound atoms. But they can also burn stuff. Now this may be a subsequent reaction with atmospheric oxygen, but it may not.

But we haven't seen anything similar with gravitation which is what you need. 

Burning on net (accounting for other byproducts beyond the spent fuel and the energy released) actually increases entropy. 

[+Oltux72]

3 hours ago, Parallax said:

But we haven't seen anything similar with gravitation which is what you need. 

Why gravitation specifically?

3 hours ago, Parallax said:

Burning on net (accounting for other byproducts beyond the spent fuel and the energy released) actually increases entropy. 

That is true.

[Guest Parallax]

On 10/18/2019 at 2:47 AM, Oltux72 said:

Why gravitation specifically?

I was thinking of this earlier comment:

On 10/5/2019 at 9:41 AM, Oltux72 said:

Very well, then the elephant in the room: Can you make it negative? This may seem a stupid question, but if you can it looks to me like you have a material that will move against external pressures, which under gravity and in air, means more or less that it can deform elastically at will.

 

[Guest Parallax]

A similar concept to modulus of elasticity is bulk modulus which is defined as follows:

Quote

The bulk modulus of a substance is a measure of how resistant to compression that substance is. It is defined as the ratio of the infinitesimal pressure increase to the resulting relative decrease of the volume.

The advantage of using bulk modulus for the surge of tension is that it is also defined for liquids and is independent of direction. 

Link: https://en.wikipedia.org/wiki/Bulk_modulus

[Pagerunner]

On 10/10/2019 at 8:08 PM, Parallax said:

@Pagerunner I was thinking about the surge of division, couldn't you define it as the surge that increase entropy within a bounded physical space? The amount of investiture consumed would depend on the change in entropy times the volume within which it was increased.

I think that's also too specific, and that Division in application is too inconsistent to be tied down to a fundamental principle like that. The rocks burning is a particularly bad example, since there is no natural phenomenon that will make a rock burn. (Okay, sure, you could have a vein of pure magnesium or some nonsense like that, but normal old rocks aren't going to react with oxygen.)

[Guest Parallax]

9 hours ago, Pagerunner said:

I think that's also too specific, and that Division in application is too inconsistent to be tied down to a fundamental principle like that. The rocks burning is a particularly bad example, since there is no natural phenomenon that will make a rock burn. (Okay, sure, you could have a vein of pure magnesium or some nonsense like that, but normal old rocks aren't going to react with oxygen.)

What I had in mind was not the rock literally burning but increasing entropy in a localized part of rock having a similar effect, in other words it would emulate burning for material that can't burn.