I don't understand something about Stellaris's hyperspace tech

[Critical Ethics]

The actual in-universe explanation:

FTL is not actually FTL.

Starships equipped with hyper drives enter a "subspace" beneath the main universe. Within subspace, there are pathways between star systems, i.e., hyperlanes, that can be safely traveled through, and since subspace is smaller than the main universe, starships arrive sooner than if they'd traveled conventionally.

When an empire discovers a new system in the hyperlane network, such as the precursor homeworlds, what they're really doing is discovering a pathway they didn't know about before. Meanwhile starships using the Emergency FTL function and science ships using Experimental Subspace Navigation are taking uncharted routes to their destination.

The mechanism doesn't matter, in a relativistic universe any method which allows you to travel X lightyears away from your starting point's subjective reference and return in less than 2X years from your starting point's subjective reference implies you can leverage this into time travel.

 

[Critical Ethics]

Yes I know

I know you know, but did you know I knew you know? No. Now you know I know you know, and you know I knew you knew, and so you know I know and knew that that you know is not new.

(Yeah I was just elaborating as Fulgrymm said)

 

[Verx90]

Light is the force carrier for electromagnetism so to "see" something is to be causally connected to it. You don't need eyeballs to "see" something as an observer, you just need to be a thing that exists. If this is a convoluted way of saying that FTL objects do not exist and therefore can not be observed then I'm 100% with you

Well.. Close to it.

If FTL exist, you can't use light to observe it, as you can't use sound to observe something that goes faster than sound.

I know sound and light are 2 very different thing, but imagine this.

You use sound to observe reality, nothing but sound.
In this thought experiment, sound can't travel faster than sound. Nothing else till then ever traveled faster than sound.

When something moves, it leave sound, you use 2 rockets that send a sound signal to determine they position.

What happen when the 2 rockets go closer or faster than sound?

They start to have timelagg, when they go faster than sound, they position is wrong in comparison to when the signal is send, the 'right' now become useless.

If you start a sound far for the observer, then travel faster than sound towards the observer and make another sound, the second sound will reach the observer before the first one.
For the observer time space was violated and the subject traveled Time.

But the subject is the only reable observer, as it still have a casualty.

The observer is victim of the limitation of perception at lower speed.

Same thing with light, If there is FTL, you can't understood it with the light system (fastest system we have right now), as it is outside your perception, if you are an observer of FTL you will percepite it as timetravel, because you are incapable of understanding the casualty.


If FTL exist, you need a new system to observe it, a system based on FTL. Light and electromagnetism become useless way to describe reality.

 

[Critical Ethics]

Well.. Close to it.

If FTL exist, you can't use light to observe it,

Why do you keep taking about light? You observe it by the ship departing from its arrival point and arriving at its destination point.

 

[Verx90]

Why do you keep taking about light? You observe it by the ship departing from its arrival point and arriving at its destination point.

no. the addition of an observer require time and space .

try to do the 2 rockets experiment , but this time, instead of the tachions , use the quantum entangled particles. no more travel time, no more timelagg .

 

[Critical Ethics]

no. the addition of an observer require time and space .

try to do the 2 rockets experiment , but this time, instead of the tachions , use the quantum entangled particles. no more travel time, no more timelagg .

If the two rockets traveling at relativistic speeds can communicate with each other and with their origin point instantly you can arrange them such that you can send messages to your past self.

 

[Olterin]

If the two rockets traveling at relativistic speeds can communicate with each other and with their origin point instantly you can arrange them such that you can send messages to your past self.

Indeed - to elaborate: the means of communication does not matter, as long as the information is transferred faster than the time it would take for a photon to get from one observer to the other, and there is a way to constantly communicate, you can arrange the two observers such that the first observer can send messages to their own past self.

Edit: The thing about quantum entaglement is that, as far as we know, there is no way to use it to actually transfer information. If you come up with one and can demonstrate it, apply for a Nobel prize.

 

[Critical Ethics]

Indeed - to elaborate: the means of communication does not matter, as long as the information is transferred faster than the time it would take for a photon to get from one observer to the other, and there is a way to constantly communicate, you can arrange the two observers such that the first observer can send messages to their own past self.

Edit: The thing about quantum entaglement is that, as far as we know, there is no way to use it to actually transfer information. If you come up with one and can demonstrate it, apply for a Nobel prize.

Invent the Nobel Prize and award the first one to yourself.

 

[Mastikator]

Well.. Close to it.

If FTL exist, you can't use light to observe it, as you can't use sound to observe something that goes faster than sound.

Super sonic airplanes can be observed with sound, they make an explosive sound, you hear the explosion when it passes you and then you hear the shockwave coming from both the destination and the origin.

I think you're getting ahead of yourself here, things traveling faster than the speed of sound absolutely can be observed with sound. A LOT actually. The same would be true for something traveling faster than the speed of light. We already know this because charged particles traveling faster than the speed of light in a medium emit Cherenkov radiation.

An FTL space ship would do the same, it would emit Cherenkov radiation that would become visible as it pass you and then the radiation would become visible from both the destination and the origin. Even if an FTL ship has no detectable black body radiation it would still be visible just from the fact that it's FTL.

 

[Verx90]

Super sonic airplanes can be observed with sound, they make an explosive sound, you hear the explosion when it passes you and then you hear the shockwave coming from both the destination and the origin.

I think you're getting ahead of yourself here, things traveling faster than the speed of sound absolutely can be observed with sound. A LOT actually. The same would be true for something traveling faster than the speed of light. We already know this because charged particles traveling faster than the speed of light in a medium emit Cherenkov radiation.

An FTL space ship would do the same, it would emit Cherenkov radiation that would become visible as it pass you and then the radiation would become visible from both the destination and the origin. Even if an FTL ship has no detectable black body radiation it would still be visible just from the fact that it's FTL.

you... missed the part where i said that nothing travel faster than sound didn't you ? ....

and sorry, but slowing down light is not realy going FTL. its just an escamotage to prove something useless.

light is radiation. thats a simplified explenation , but naturaly it would leave radiation if you slow it down. or any particle that is traveling faster in said object that slowed light , would probably leave a wave .

If the two rockets traveling at relativistic speeds can communicate with each other and with their origin point instantly you can arrange them such that you can send messages to your past self.

well, thats a big IF . with us using a system that require a limit speed, thats seems to be the case. as we can't realy test this . math is not rapresentative of reality , it just try to describe it .

but realisticaly is pure nosense , apart from the fact that there doesn't exist FTL way of comunication , we can't even get close to lightspeed .

so... let the idea that FTL is achivable , and FTL comunication is a thing . lightspeed is not the upper limit.

time appear to be the problem in this mental exercise. the math we have now, come to the conclusion that going faster than light will break time\space .
why? why it wasn't sound speed the limit of space\time ? why it wasn't going 10 km\h or anything else? why it doesn't happen if not in our mathematical problems?

simple, we don't understand time OR FTL doesn't exist.

if you want FTL to exist, you have to understand that our current theory MUST be wrong.
now, in math this is something we usualy do, and end up PROVING the theory was right ,so we would probably end up proving there is no FTL .



but keep the assumption that FTL is real, theory is wrong.

i've a board with the information to go left , i go left with FTL but there is no way left, so i FTL back and tell an observe that i was wrong with FTL, and to go right.
the observer then FTL and tell me i was wrong and to go right.

all this happen in FTL speed, information and travel .

this mean that evrything happened in a system that goes FTL , in this system , time is mainteined and casualy isn't altered. since evrything while going faster than light, still goes at the same speed. observer and subjects are in the same system and comunicate instantly .

but evrything happened at the same time? we didn't put an actual distance because i realy don't want to calculate the time passing at FTL speed of short distances .

why there should be timetraveling effects? why we considerate time as something that can go negative?

simple, we can't demonstrate it can go back, as we can't demonstrate it can't go backwards. i'm talking in a universe where FTL EXIST , we don't understand time.

 

[Critical Ethics]

why there should be timetraveling effects? why we considerate time as something that can go negative?

Because that's how relativistic time dilation interacts with FTL.

If you are an object with mass traveling away from me at sub-light speed relative to my reference frame, you are experiencing time slower than me. The faster you're going the greater your mass compared to mine and as such the slower your time. If you were traveling at c in my reference frame you would have infinite mass and would have required infinite energy to get there, which is why you can't go faster than c just by putting more gofast into your rocket. Light has no mass so (in a perfect vacuum) it is traveling at c all the times in every reference frame. e: this is a hugely simplified and not entirely accurate explanation but it's close enough for a lazy post on a space game forum

But any time you are described as traveling relative to me it can also be described as me traveling relative to you. So you are traveling away from me and experiencing time slower than me in my reference frame, and I am traveling away from you and experiencing time slower than you in your reference frame. Both of these statements are true, and both are happening at the same time. The apparent contradiction is not a problem because our reference frames only matter to each other when they intersect, and one of us turning around to go back and meet up breaks the symmetry.

It is a problem if you also have hyperspace or warp drive or wormholes or whatever that allow you to get from point A to point B faster than c. If we pass each other at 0.866c (when time happens half as fast in the other person's reference frame), and two days later "your time" you "instantly" jump to me, what time do you arrive "my time"? One day after we passed each other? Two days? Four? All of these are valid answers depending on how your FTL works, and all of them in some way allow for backwards time travel.

You can have FTL, but not in a universe with relativistic time dilation and linear causality. You get to pick two. No time dilation means no reference frame conflicts means no time travel from jumping between reference frames, so as I said earlier the simplest answer is that Stellaris's universe doesn't work by our physics and relativistic time dilation just isn't a thing.

 

[Coconut_Cookie]

Being as it facilitates FTL telecommunications and transportation, how does it avoid breaking causality in a galaxy thousands of light-years across?

e.g. Sol and Alpha Centuri are approximately 4 light years apart, which means a UNE colony ship on Alpha Centauri III had landed sometime before the order to build said colony ship was issued to Sol Starbase shipyard (from the viewpoint of the Alpha Centauri system). Without an absolute frame of reference, how do objects in different star systems know when "now" is and not accidentally go back in time?

Well...it's just a game. That being said I think that ftl is trivialized a lot. Colonizing or conquering worlds in other solar systems would a be massive if not nearly impossible undertaking even if you would have the ability to travel there in any reasonable amount of time. The early game is over way too fast ever since megacorp. There's no time anymore to explore the galaxy, it's all about finding choke points and spamming outposts. In the first release version the map painting wasn't that bad but right now the main focus is map painting.

 

[Verx90]

Because that's how relativistic time dilation interacts with FTL.

If you are an object with mass traveling away from me at sub-light speed relative to my reference frame, you are experiencing time slower than me. The faster you're going the greater your mass compared to mine and as such the slower your time. If you were traveling at c in my reference frame you would have infinite mass and would have required infinite energy to get there, which is why you can't go faster than c just by putting more gofast into your rocket. Light has no mass so (in a perfect vacuum) it is traveling at c all the times in every reference frame. e: this is a hugely simplified and not entirely accurate explanation but it's close enough for a lazy post on a space game forum

But any time you are described as traveling relative to me it can also be described as me traveling relative to you. So you are traveling away from me and experiencing time slower than me in my reference frame, and I am traveling away from you and experiencing time slower than you in your reference frame. Both of these statements are true, and both are happening at the same time. The apparent contradiction is not a problem because our reference frames only matter to each other when they intersect, and one of us turning around to go back and meet up breaks the symmetry.

It is a problem if you also have hyperspace or warp drive or wormholes or whatever that allow you to get from point A to point B faster than c. If we pass each other at 0.866c (when time happens half as fast in the other person's reference frame), and two days later "your time" you "instantly" jump to me, what time do you arrive "my time"? One day after we passed each other? Two days? Four? All of these are valid answers depending on how your FTL works, and all of them in some way allow for backwards time travel.

You can have FTL, but not in a universe with relativistic time dilation and linear causality. You get to pick two. No time dilation means no reference frame conflicts means no time travel from jumping between reference frames, so as I said earlier the simplest answer is that Stellaris's universe doesn't work by our physics and relativistic time dilation just isn't a thing.

OK. I get the problem there...

Our phisics definitions are traduced in math, and with it we calculate how reality will react to certain events.

With this, we know FTL is impossible, as it would create time travel.

But the whole thought experiment require FTL to work .

So you have to understand that you require a new system, because the (non) reality show FTL that doesn't result in time travel, a theory is useful only if it describe reality. And in Our thought experiment FTL break our phisic theory.

Since you have a rule that say that FTL will result in time distorsion, but (non) reality show a different result, in our thought experiment our reletavistic theory is wrong.

 

[prismaticmarcus]

OK. I get the problem there...

Our phisics definitions are traduced in math, and with it we calculate how reality will react to certain events.

With this, we know FTL is impossible, as it would create time travel.

But the whole thought experiment require FTL to work .

So you have to understand that you require a new system, because the (non) reality show FTL that doesn't result in time travel, a theory is useful only if it describe reality. And in Our thought experiment FTL break our phisic theory.

Since you have a rule that say that FTL will result in time distorsion, but (non) reality show a different result, in our thought experiment our reletavistic theory is wrong.

yeah, the thread seems to be about your thought experiment.

 

[Critical Ethics]

OK. I get the problem there...

Our phisics definitions are traduced in math, and with it we calculate how reality will react to certain events.

With this, we know FTL is impossible, as it would create time travel.

Our current understanding of physics e: ISN'T saying FTL is impossible because it will create time travel, it says that if FTL is possible then it implies time travel. Maybe time travel is possible?

But the whole thought experiment require FTL to work .

So you have to understand that you require a new system, because the (non) reality show FTL that doesn't result in time travel, a theory is useful only if it describe reality. And in Our thought experiment FTL break our phisic theory.

Since you have a rule that say that FTL will result in time distorsion, but (non) reality show a different result, in our thought experiment our reletavistic theory is wrong.

Are you saying that relativistic time dilation must not be true in reality, or are you saying relativistic time dilation must not exist in stellaris? If you mean in reality then we have experimental evidence of relativistic time dilation and nothing that directly contradicts it. If you mean in stellaris then yes, that's literally the first reply

Easy answer, time dilation is not part of the game's mechanics.
Stellaris is just a game and not an acurate reflection of reality.

e: left out some important qualifiers and an important "isn't"

 

[prismaticmarcus]

Maybe time travel is possible?

time travel is ONLY possible AFTER the technology is designed and built. good luck with that...

 

[Primarch Victus]

Stellaris is a game, my friend! A very, very good one. And it don't need to be hyper-realistic to be fun. If you really want a space game with real-world physics, I suggest that you go to play Kerbal Space Program or Children of a Dead Earth .

 

[Liquid Ghost]

Me reading this thread.​

 

[Verx90]

yeah, the thread seems to be about your thought experiment.

The thought experiment is stellaris(or any scify really where FTL exist) ........ A universe where FTL exist and is implemented require our phisic theory to be wrong. Since there is no time scenaningans with FTL at least...

The worm still love you.

 

[Verx90]

Our current understanding of physics e: ISN'T saying FTL is impossible because it will create time travel, it says that if FTL is possible then it implies time travel. Maybe time travel is possible?

Are you saying that relativistic time dilation must not be true in reality, or are you saying relativistic time dilation must not exist in stellaris? If you mean in reality then we have experimental evidence of relativistic time dilation and nothing that directly contradicts it. If you mean in stellaris then yes, that's literally the first reply


e: left out some important qualifiers and an important "isn't"

I am talking strightly of a universe that is not our reality, where FTL is implemented without time travel.


And in our reality, time travel is chained with FTL for our understanding of phisic, it is a possibility, but not an actual reality yet as we have no actual proff.

For now the only thing we are sure change time is gravity, well.. The quantity of energy change gravity and it for some reason alter time.

Our math come to the conclusion that FTL have time travel repercussion, but this would not be the first time a theory is not wrong but simply incomplete and reach a slightly wrong conclusion.

And considering what we can observe, and that there seems no stars that warp around, or object that appears from nothing, I'm quite convinced that timetravel doesn't exist, as such our theory is incomplete or it is complete, and the fact that FTL require timetravel showcase an impossibility.