Idea of how Allomantic FTL would work

[Zoey]

I have a theory of how the FTL would work in the Cosmere, and just wish to share my idea here to see what others think about it. 

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Steeldancer (paraphrased)

Have you ever heard of the Alcubierre Drive? 

Brandon Sanderson (paraphrased)

Yes, I know about the Alcubierre drive. 

Steeldancer (paraphrased)

So, if we took two speed bubbles--mechanized, because Allomancers aren't powerful enough to pull it off--could we create a functioning Alcubierre drive?

Brandon Sanderson (paraphrased)

You are theorizing in the right direction. 

This was found in FanX Spring 2019 (April 19, 2019), for those of you wondering. 

 

Now, the Alcubierre Drive functions through the creation of a Spacetime Topology which has space compressed on one end of the ship, and expanded on the other. This works in accordance and does not break Einstein's Field Equations. It is very complicated, so I will not go fully into how they are thought to operate in the real world, but you should already be seeing where I am going. 

Allomantic Cadmium and Bendalloy both are able to, in a localized area, expand and contract time. This is notable, due to the fact that Space and Time, in General Relativity and other fields, are fundamentally interchangeable. Which leaves on to question if it is theoretically possible that a skilled Allomancer could apply the effects of these Metals to Space instead of Time. Therefore causing Space itself to expand and contract like they do to Time. This would be able to create an effect nearly identical to the Alcubierre Drive, creating a very similar Spacetime Topology. 

This could be done through some sort of automated, mechanical Allomancy, and mix this with Duralumin and one could further intensify the degree of warping which occurs. This would allow one to go, essentially, faster than light, while remaining in adherence to the Laws of General Relativity on a local scale. This does require negative energy, or a infeasible amount of energy. But this can easily be overcome with Cadmium and Bendalloy being used to bring about the proper curvature and topology. 

Now, one of the major issues with the idea of this, is heat and energy production with the warping, 

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 C. Hawking radiation inside the bubble

We study now the behavior of the RSET in the center of the bubble at late times. Here ρst = 0, because ¯v(r = 0) = ¯v 0 (r = 0) = 0. Integrating Eq. (3), one realizes that u(t, r) is linear in t so that, for fixed r, it acquires 7 time arbitrarily large positive values. One can evaluate ρdyn from Eq. (19) by using a late-time expansion for f(u), which (up to the first non-vanishing order in e −κ1u ) gives f(u) ≈ κ 2 1 , so that ρ(r = 0) ≈ κ 2 1/(48π) = πT2 H/12, where TH ≡ κ1/(2π) is the usual Hawking temperature. The above expression is the energy density of a scalar field in 1 + 1 dimension at finite temperature TH. This result confirms that an observer inside the bubble measures a thermal flux of radiation at temperature TH.

-Carlos Barceló, Stefano Finazzi, Stefano Liberati (2010) "On the impossibility of superluminal travel: the warp drive lesson"

 

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Even if the above described semiclassical instability could be avoided by some external action on the warpdrive bubble (or by some appropriate UV completion of the quantum field theory, like in [19]), the QI lead to the conclusion that the Hawking radiation in the center of the bubble will burn the internal observer with an excruciating temperature of TH ∼ κ & 10^−2 TP , where TP is the Planck temperature, about 10^32 K. This would prevent the use of a superluminal warp drive for any kind of practical purpose.

-Finazzi, Stefano; Liberati, Stefano; Barceló, Carlos (2009). "Semiclassical instability of dynamical warp drives"

These show that the Warp Drive would likely produce large amounts of heat, but, theoretically, a skilled Feruchemist could find a way to take this heat production and store it in metals in order to help the people within it not perish due to the heat production. Like with the Warp Bubbles, this could also possibly use some form of automated feruchemy, if something of that sort is ever discovered in the future. 

This fits with the knowledge Sanderson has of Warp Drives, theoretically can be done with Allomancy, and also does not violate causality, which is an issue Sanderson was aware of with FTL Travel, 

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When the proposed metric is modeled, there are a number of fascinating phenomena which result. The spacetime is flat in all locations except within a certain region with a defined radius, which allows for localized space distortion. In addition, the time of the local, centralized region is the same as that of the observer, which indicates no time dilation effects, however the region itself moves along a time-like curve, resembling geodesics. This appealing feature allows the concept to function without a violation of causality. 

 

An Examination of Warp Theory and Technology to Determine the State of the Art and Feasibility- Joseph Francis Xavier Agnew

 

Further support is in how the Time Bubbles are called as they are, as the are close to the term "Warp Bubble", and the shimmering border and how everything that passes through it being disturbed does fit with the idea of a topological defect like that formed by a Warp Drive. Which, while not significant backing, does help support my point. 

This does have the issue of assuming it can warp space, but according to physics it should be able to. This does also fit with the idea of Sanderson saying that FTL  Allomancy uses concepts and uses of the Metallic Arts we are not familiar with yet, this, I believe, could be in reference to Spatial Manipulation. As he did imply that the Tables are only human ideas of how they are organized rather than some kind of Rule. So it is possible that Cadmium and Bendalloy are not purely temporal. 

So, what do you think of this theory? Does it sound plausible? 

Edited June 9, 2021 by Zoey

[GoWibble]

From the first paper you cited:

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Hence, if the QI hold, then Planck-size walls would lead to an excruciating temperature of the order of the Planck temperature TP (10^32 in the Kelvin/absolute scale or in whatever temperature scale one adopts!).

... When you just copied and pasted the equation we lost the nuance that it was 10^32 K, not 1023 K. Slight difference there. 

Brass melts at about 930*C, which is a little above the 1032 K, but 930*C < 10^32*C. I don't see how a Feruchemist could keep their metalminds from melting when the environment is 10^32*C, and I do not find it feasible that they could store that much heat. 

This could be pertinant, but I didn't really follow those papers very well:

Spoiler

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r0ax_

How do you research the physics elements of your books? How much would you say you later the laws of physics, and how much do you respect them?

Specifically wondering about Skyward?

Brandon Sanderson

I, these days, am able to cheat on this a little bit, because I know I have a really good support structure of people who have actually studied physics, rather than myself, where I have flirted with studying physics. I am not a scientist, but I love pop science, if that makes sense. I'm the person who loves to read a book about someone doing science, but when I was a chemistry major in college, the actual physical labor of running experiments was mind-numbingly boring to me. And so I like to know. I like to know what rules I'm breaking, and how to play with them. But these days, I'm really able to trust my basic pop science studies. So, I'm not going to go read seven textbooks on physics. What am I gonna do? I'm gonna go to YouTube and say, "All right. What does it actually look like for someone to pull X number of g's." And I will watch those videos. (There's actually some really good ones on YouTube about that, specifically.) I'm going to go read blog posts, because our internet is so great, from pilots talking about their experiences. That's what I'm looking for. I'm not looking for what the physicist says happens. I'm looking for: how does a pilot describe it, and how is it presented for a layman.

And then, I am going to do my best and find experts to read the book for me and tell me where I'm wrong. I often say that you can get yourself most of the where there in research as an author with a minimal amount of time. You just need to find an expert, who spent all the extra time that it takes to become a true expert, to read your book and tell you where you're wrong. Preferably, a couple of people, because it turns out people in any profession disagree with one another greatly on some points, and it's good to know which points those are.

So, that's literally what I did for Skyward. YouTube videos, firsthand accounts, and a couple of pop culture essays. Stuff that's only, like, two to five thousand words long, about what the experience feels like and why it's working like it's working. Followed by getting some physicists and some fighter pilots both to read my early draft and tell me what I was doing wrong.

How much do I try? Sanderson's Zeroeth Law says "always err on the side of what's awesome." What this means for me, realistically, is: I want to tell a good story. And telling a good story takes precedent over basically anything else. That means that I don't want to break laws for physics for no reason, and I want to know when I'm breaking laws of physics. But I am going to find a cheat that lets me tell the story the way I want to tell it, if there becomes a conflict. The most famous one for me of this is the redshift that would happen when you make time bubbles in Era 2 of Mistborn. When I was working on this and researching it and be like "what would actually happen," turns out that a lot of the research I was reading said that you would redshift the light, and you would really have a chance of irradiating everybody outside or inside the bubble, depending. And I just had to say, "You know what? I've gotta come up with a law in the magic system that fixes this and makes it not happen. Because otherwise, I just can't do the magic, right?" That was good for me to know, but it's also a place where I just decided to cheat. And we can, as fantasy authors, cheat.

YouTube Livestream 1 (Jan. 11, 2020)

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Kurkistan

Is there- have you come up with a Realmatic explanation for why light isn't affected by time bubbles besides handwavium "please don't burn people with microwaves"?

Brandon Sanderson

Peter's got one for us. 'Cause we were going to do redshift: like the actual original writing for it had redshifts; Peter's like "Dude, you will microwave everybody" I'm like "Oh man". So the handwavium of that: there is a real- there is an actual explanation, but it...

*they move to outside the store*

What's the middle of this question?

Kurkistan

Middle of the question was you were thinking about explaining the Realmatics behind light for time bubbles.

Brandon Sanderson

Oh right, right right right right. I can't because it spoils future books; like that's spoiler for Mistborn... 10?

Kurkistan/Argent

*laughter*

Brandon Sanderson

So... if you count the four Alloys, so really gotta stay away from stuff like that.

Kurkistan/Argent

That's fair/fine.

Firefight Chicago signing (Feb. 20, 2015)

 

13 hours ago, Zoey said:

Allomantic Cadmium and Bendalloy both are able to, in a localized area, expand and contract time. This is notable, due to the fact that Space and Time, in General Relativity and other fields, are fundamentally interchangeable. Which leaves on to question if it is theoretically possible that a skilled Allomancer could apply the effects of these Metals to Space instead of Time. Therefore causing Space itself to expand and contract like they do to Time. This would be able to create an effect nearly identical to the Alcubierre Drive, creating a very similar Spacetime Topology. 

Because space and time are intrinsically related, if you expand time, space should expand as well. This should also hold for contracting. 

 

This kind of theory has been floating around for a while, and I think that it holds some promise as a possibility for FTL for Scadrial at least.

[Zoey]

2 hours ago, GoWibble said:

From the first paper you cited:

... When you just copied and pasted the equation we lost the nuance that it was 10^32 K, not 1023 K. Slight difference there. 

Brass melts at about 930*C, which is a little above the 1032 K, but 930*C < 10^32*C. I don't see how a Feruchemist could keep their metalminds from melting when the environment is 10^32*C, and I do not find it feasible that they could store that much heat. 

This could be pertinant, but I didn't really follow those papers very well:

  Hide contents

 

Because space and time are intrinsically related, if you expand time, space should expand as well. This should also hold for contracting. 

 

This kind of theory has been floating around for a while, and I think that it holds some promise as a possibility for FTL for Scadrial at least.

I know it is 10^32, I just didn't catch that it didn't transfer over like that, thanks for pointing that out. I fixed it. 

And yeah, that is an issue, melting it and all. My theory isn't complete, but it is at least a start. Maybe to help to have a metalmind that could store more one can through some method compress it into smaller and smaller volumes. But not sure if it is volume or mass which is important for how much it can store. 

This of course does still have the issue of it melting down and being further turned into gas and into plasma. 

 

Edited June 9, 2021 by Zoey

[Steeldancer]

I came up with this theory ages ago. That's why I asked about it haha. 

And I still love it. Good point with the thermodynamics, but let's note that there are some laws of thermodynamics in regards to investiture we don't know about yet. 
Or at least I don't know about it. I've been out of the loop for 2 years so don't blame me too much. 
For the record, I think fabrials will probably be how Roshar reaches FTL.