FTL Shenanigans, Relativity, and the Denial of Time Travel

[CoderDrag0n8 He/They]

In IotE, there are 3 mentions of FTL (I included 3 because the 1st doesn't give much besides it exists)

Spoiler

Ch 36 Page 294

"Currently, ships had to use FTL to reach Lumar for aether harvesting--either that or pay for more powerful, but more regulated, versions available from Aditil's people."

(Proof of FTL travel)

Ch 55 Page 466

"While that's up, Dajer will have no sensors, no FTL communication, no nothing for any of the ships."

(Proof of FTL communication)

This video explains how FTL would cause time travel in a simple to understand way (although it is in the middle of a bunch of other science talk, so you don't have to watch it, but it is fun science talk)

Spoiler

 

TL;DR FTL travel or communication cause time travel.

But, Brandon has stated that Time Travel will not be something he's gonna do.

Spoiler

Adam Horne

A few people have wondered if we're ever going to see time travel in the cosmere.

Brandon Sanderson

Time travel into the past is something that I decided very early in the life of the cosmere that I was not going to deal with. So people can time travel into the future, but we can do that right now - not very much, but if you go fast, you are time traveling into the future by laws of relativity, and it's easier to do that in the cosmere. There are a couple things for storytelling that really throw a lot of wrenches into your worldbuilding. One of them's time travel; as soon as you introduce time travel, it changes everything.

Another one is bringing characters back from the dead, and since my very first cosmere book starts with someone being resurrected in chapter one, I knew that people coming back from the dead was not something I could have a hard fast rule against in the cosmere. Multiple books are based on the idea of people being resurrected; that's where Warbreaker and Elantris both come from, is that kind of idea.

Since I knew I was going to be doing that one, the other two that I think that really mess with things in strange ways are alternate dimensions and time travel. And that's when I just said I'm going to put those both off-limits in the cosmere. You saw me doing alternate dimension stuff in Steelheart, in part because I won't let myself do it in the cosmere. I'm already playing with fire with the way that people can become cognitive shadows in the cosmere, and I don't want to have the other two messing up narratives and storylines and things on the level that they would. So no time travel into the past ever in the cosmere.

YouTube Livestream 1 (Jan. 11, 2020)

So here's my question. Is Brandon just going to brush away the time travel implications of FTL, explain it away with investiture, not address it, or go back on his rule? Probably not address it, this is very very very random sciency of me, and I just wanted to say that I proved time travel is possible in the cosmere.

[PanLin they/he]

Well, it's specifically time travel into the past that Sanderson has ruled out for the Cosmere. He explicitly states in that quote that relativity is a-ok (we've seen local examples of it with time bubbles), as is time travel into the future.

The three-realms model actually gives a cleaner solution to FTL/information/observer paradoxes. Spooky action at a distance? Oh nah, they just communicated through the spiritual realm, where physical distance doesn't mean anything.

 

1 hour ago, CoderDrag0n8 said:

Probably not address it, this is very very very random sciency of me, and I just wanted to say that I proved time travel is possible in the cosmere.

Did you?  now don't get me wrong, I LOVE time travel in media. I specifically love consistent time travel. I just don't see anything in our real world understanding of the universe that means time travel into the past is automatically possible in the Cosmere.

 

Also, I started watching the video but there aren't any chapters or anything—if you could link me the timestamp of the time travel bit you're referring to, I'll happily watch that specifically and come back to you! The only bits I could see scanning through were the problems with FTL in the non-local Newtonion model that helped lead to the development of general relativity, and a discussion later in the video explaining why entanglement straight-up can't send information (let alone mass) into the past.

 

 

[Treamayne]

3 hours ago, CoderDrag0n8 said:

TL;DR FTL travel or communication cause time travel.

But, Brandon has stated that Time Travel will not be something he's gonna do.

So here's my question. Is Brandon just going to brush away the time travel implications of FTL, explain it away with investiture, not address it, or go back on his rule? Probably not address it, this is very very very random sciency of me, and I just wanted to say that I proved time travel is possible in the cosmere.

I think the premise is a basic misunderstanding of what "FTL" means in the Cosmere. You are trying to apply IRL definitions (an object traveling at speeds greater than 1c) to something that is fundamentally different. In the Cosmere, FTL means, for example, "I can travel from Taldain to Roshar faster than the light of AisDa can reach Roshar" Traveling Shadesmar is FTL, Starling's Ship in IED is using FTL, Elsecalling from Ashyn to Roshar was FTL (8k+ years before Dajer was born). There are FTL methods using investiture hinted to come. We don't know what they are and we don't know if it truly means travelling at objective speeds greater than 1c (rather than possible subjective speeds, like Time bubbles).

I do not think you can use the phrase "FTL" in IED to explicitely mean "Travelling in the physiclal realm at speeds faster than 1c."

WoBs

Spoiler

Quote

Steeldancer

A while back, you mentioned that if certain circumstances hadn't happened on Taldain, that Taldainians... the people on Taldain probably would've been the first to space. Which interests me greatly, because they don't really have a magic system that is very conducive to faster than light travel.

Brandon Sanderson

I didn't say--did I say FTL?

Steeldancer

You didn't, that's true, but that doesn't change my question. So my question is, is there a method, other than Allomantic ways and Surgebinding ways, for faster than light, that could be achieved on any minor Shardworld, as long as they have access to Investiture?

Brandon Sanderson

Yes, there is, but it depends on if you could get in Shadesmar. You could travel FTL in the Physical Realm through Shadesmar. Basically, just take a spaceship in Shadesmar and travel between Shardpools and you've achieved FTL. Because travel through Shadesmar, you could walk between planets in Shadesmar. So anyone who can get in and out of Shadesmar reliably can FTL. Ways in and out of Shadesmar are very rare, which is extremely limiting, but it is possible.

FanX 2021 (Sept. 18, 2021)

Quote

Eric Peters

You mentioned friday night in #Seattle Allomacy has "FTL" built into it, any more hints you can share on how that would work

Brandon Sanderson

It involves where the lost energy from thermodynamic issues goes in certain Allomantic interactions.

Tor Twitter Chat (Nov. 14, 2011)

Quote

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. 

FanX Spring 2019 (April 19, 2019)

Quote

Questioner

You talked about Mistborn being the space traveler ones. I was wondering if you were going to utilize some of the speed bending into that, into the travel with it?

Brandon Sanderson

You will see what I do when I do that... The biggest problem is, for you physics majors, how we make sure that we're not breaking causality... So breaking causality is kinda my big no-no. For instance, I have right now that moving between Oathgates goes at the speed of light. But technically we still break causality, right, with Shadesmar stuff... But the issue--the way we can do it in Shadesmar is because it breaks causality, but there is so muc-- Like if you were able to go into Shadesmar, move at the speed of light, come out like, you could break causality but it's, in practice, impossible, because the difference is so slight.

We also break causality with the Spiritual Realm, but I can control that.

Questioner

Also you can just kind of like, mulligan that off.

Brandon Sanderson

...If we were having instant speed, communication and things like that... yeah if we have an ansible, that's how we're not breaking causality. How we're not doing the train thought experiment which breaks my brain...

So that's the big thing I have to worry about once we get to the Mistborn era, the space travel and stuff. Like, right now I don't break causality, or at least if I do, it is indiscernible to human ability to realize it. Once we get to actual space travel, and actual FTL, then I want to have rules in place, even if it is just like the rule for red shifts. On speed bubbles, where I say, "Yeah it just doesn't happen." Letting you know. But it would be no fun. Even if it's just that. But I at least want to have that in hand.

Emerald City Comic Con 2018 (March 1, 2018)

Quote

Questioner

As the cosmere enters the space age, will spaceship travel become the preferred method due to the Cognitive Realm lengthening as knowledge of the cosmos improves?

Brandon Sanderson

Excellent question. The Cognitive Realm will enlarge as understanding improves, but here's the thing. Human beings are really, really, really, really bad at conceptualizing large numbers, spaces, and things like that. So, even as they imagine how big the space between planets is, it's going to actually be a fraction of the actual distance. So, traveling through the Cognitive Realm will remain the preferred method and remain much faster, unless you can get true FTL, which is still very expensive and difficult. I think it's still gonna be the preferred method. But you're right; Shadesmar will lengthen, the distances will lengthen between planets as people's conceptions of them more accurately represent real life.

General YouTube 2024 (Oct. 31, 2024)

 

Hope that helps

Edited May 8 by Treamayne
SPAG

[CoderDrag0n8 He/They]

2 hours ago, Treamayne said:

I think the premise is a basic misunderstanding of what "FTL" means in the Cosmere. You are trying to apply IRL definitions (an object traveling at speeds greater than 1c) to something that is fundamentally different. In the Cosmere, FTL means, for example, "I can travel from Taldain to Roshar faster than the light of AisDa can reach Roshar" Traveling Shadesmar is FTL, Starling's Ship in IED is using FTL, Elsecalling from Ashyn to Roshar was FTL (8k+ years before Dajer was born). There are FTL methods using investiture hinted to come. We don't know what they are and we don't know if it truly means travelling at objective speeds greater than 1c (rather than possible subjective speeds, like Time bubbles).

I do not think you can use the phrase "FTL" in IED to explicitely mean "Travelling in the physiclal realm at speeds faster than 1c."

WoBs

  Reveal hidden contents

 

Hope that helps

Mmm that makes more sense, thanks!

[Verdance he/him]

You’re going to hate me but Orson Scott Card has some amazing sci fi rules based around FTL things

rhe ansibles and also spoilers

go read the ender series please its amazing

Edited May 8 by Verdance

[Schizoposting]

To add to what @Treamayne said, we can pretty safely assume that the speed of causality is faster than the speed of light, so traveling faster than the latter doesn't violate the former any more than breaking the sound barrier does. I'm not a physicist, but as far as I know, this is fully compatible with relativity.

But even if it isn't, we can just suppose that the Cosmere is based on different natural laws than our universe.

[Nitpicking]

FTL means time travel to the past, full stop. Relativity allows FTL via wormhole,  and that does result in time travel and acausality. 

Brandon will ignore this under Rule of Cool.