Why FTL?

[TheBeautifulVoid2]

Once again, I don't really understand, how does FTL equal time travel? From my limited understanding of physics, it'll only result in the visibility of time travel, but the object WON'T appear in the new place before it left, it will simply look like that because photons won't be fast enough to catch up to it, resulting in an afterimage, not time travel. Is there something in relativity that overwrites regular logic when approaching relativistic speeds? Sorry for my ignorance, but I'm no physicist, merely a linguist-in-training who likes to read up on physics.

Hi Destiny's Player. I don't know if you read it, but I made an attempt to explain how it works here.

The important thing to remember is that there is no universal time. If you can keep that in mind, special relativity isn't that hard.

 

[Cannes]

Yo

To be a little bit more specific, the theory of Einstein's Relativity, if that is the right source, is that for mass to travel up to light speed or beyond, requires an increasing amount of energy to the point where it becomes infinite.

Now accelerating a photon to light speed isn't that difficult, because that's just energy, even if it is a wave/particle hybrid in behavior. If there was a way to convert mass into tachyons to ride a tachyon stream or some other energy, and then convert us back to matter with the same pattern quantum data field at the destination, then effective FTL might be achieved in that manner. But trying to accelerate matter to light speed or beyond, still hits against the mathematics and physics of the known universe. Just the known universe though.

The reason why I split the difference between faster than light vs effective faster than light, is because the physicists like to be specific. So if you ask the EM drive's creator "is that a reactionless drive", he answered in a video that "it has a reaction to get the propulsion". Even if that is merely the reaction of electro magnetic forces. But many people use reactionless drives in reference to a Newtonian drive, which is not quite the same thing as not having a reaction drive the propulsion force.

You have som very serious misconceptions about particle physics here and have completely misunderstodd the concept of these proposed methods of FTL travel.

First of all you do not accelerate photons to the speed of light. Photons travel at the speed of light, period! They are incapable of traveling at any other speed.
Second: Convert matter into tachyons? Tachyons are still very much theoretical, even more so than wormholes and alcubierre drives. Matter is a property of energy, wether in the future some fundamental link between tachyons and energy will be found is beyond speculation and does not really fit into the scope of Stellaris.
Thirdly: None of the methods of FTL travel proposed rely on acceleration, thus they never come into conflict with the infinite amount of energy needed to accelerating something with mass to the speed of light.

 

[Safehold]

Photons travel at the speed of light, period!

To me that means the ability of humans to manipulate the light speed is almost near zero. Particle accelerators can accelerate sub particles at CERN to smash things and then detect HIggs Boson existence as a result of that acceleration. That's how many of the experiments have proven the contentions of the quantum Standard Model.

Yet if it is as you say, light and photons cannot be de-accelerated or accelerated, then there is little evidence on the manipulation of light, let alone light speed. That doesn't block effective FTL drives, that was a different topic though.

Convert matter into tachyons? Tachyons are still very much theoretical

Both would be theoretical, same as the mathematical theories behind the Alcubierre drive, wormholes, black holes, warp, hyperlanes, or anything else of that nature. Of course, the stuff at the end, hasn't been researched as much. So it's more like a hypothesis, not even a theory.

None of the methods of FTL travel proposed rely on acceleration

They don't have to rely on acceleration. My point is that normally FTL drives are considered physically impossible because people are trying to accelerate something with mass, to a speed near light speed.

As for particle physics, today's world is on the edge of various breakthroughs, which will render much of the previous models of physics either questionable or in need of major updates. Just as Einstein overruled the Newtonian equations on some issues (or maybe all issues as the case may be) because it was more accurate, the Standard Model of quantum physics has the potential to do the same to some of what is commonly accepted from Einstein's works. Stephen Hawking stated in public that he bet that the Higgs Boson did not exist. Right before the experiment at CERN detected the presence, presumably by calculating for the conservation of energy when colliding particles together. Said calculations being in line with the expected model output of the Standard Model.

 

[Person012345]

As I said, as we understand it, Superluminal communication is impossible. Tachyons are hypothetical and have not been observed to exist. Information cannot travel faster than light. Quantum entanglement, as I have come to understand it, does not break the rules for FTL information transfer.

And I don't suppose you're going to actually answer the question which is why? What rule prevents information arriving somewhere before a beam of light. He didn't just say "we can't do it yet" he said it was a fundamental impossibility (like accelerating to a speed higher than c is).

 

[Person012345]

Hi Destiny's Player. I don't know if you read it, but I made an attempt to explain how it works here.

The important thing to remember is that there is no universal time. If you can keep that in mind, special relativity isn't that hard.

Does your scenario also apply to objects that are simply very far away communicating (and not exclusively to a scenario with time dilation)?

 

[stumason]

The current research is for the EM drive which is not the same as any FTL drive. The thing about EM drive is that it is a reactionless thruster. It is like a thruster in Kerbal that does not require fuel of any kind, only power. This is HUGE, but it is not FTL. It is also supposed to be impossible, but when NASA tried to disprove it, it behaved exactly as advertised. They also measured that it did in fact bend space time, which it also shouldn't but there is a big leap from bending spacetime to FTL. Remember, a bicycle bends spacetime.

JPL are actually working on Warp field research, so yes, they are working on "FTL".

The EM drive is a separate line of inquiry for a separate form of sub-light propulsion.

 

[13Foxtrot]

And I don't suppose you're going to actually answer the question which is why? What rule prevents information arriving somewhere before a beam of light. He didn't just say "we can't do it yet" he said it was a fundamental impossibility (like accelerating to a speed higher than c is).

As an object or information travels closer to the speed of light it takes more energy to move an object that gains more mass. The faster something goes the heavier it gets. The speed of light makes some something infinitely heavy and requires infinite energy to propel it. That is why the speed limit. An object is just information and vice versa. So the speed limit of information.

The only time information can travel faster than light is during inflation. It is called propagation of information. As long as you are not transmitting information like light, something can happen faster than light. The edges of the universe moved faster away from each other than the speed of light only because they could not "see" each other. That is a very basic description of inflation.

 

[stumason]

At point A, in 10 minutes, a guy will shoot someone at Point B with a 0.9c projectile. You go to point B at FTL, method of FTL irrelevant, and wait for point B guy to be shot. Then you travel back to A with FTL, method of FTL irrelevant, and you arrive BEFORE point A guy has shot the projectile. What happens if you stop him? This is why FTL violates causality, regardless of means. This is a gross oversimplification, but that is how it would work according to relativity.

Why would that happen? If you wait for the guy to be shot at point B, why would you end up at point A prior to the projectile being shot?

Sounds bloody stupid.

 

[stumason]

The problem with actual FTL is that the faster you go the slower everything get's. Reactions of your atoms slow down. The barrier comes with light speed where every reaction starts to stop and to go faster you have to reverse the reactions. So time turns back. Theoretically you would arrive before you started.

No, you wouldn't, because you are not travelling faster than light - you are warping space to make it appear like you are, but you're not.

 

[Dauntasa]

the concept of a grand space game without FTL travel or communication is interesting but likely hard to implement in any way that is fun

 

[kiny5]

Astrophysics student here. If you are interested in finding out the practicality of future technology I suggest you read Michio Kaku The Science of the Impossible (also a TV show (sci fi Science) but i cant speak to its quality as i haven't seen it.)

FTL in science fiction is based off the idea that its technically not impossible, just very very hard. The Wormholes are the most scientifically sound forms of travel as there are technically ways to make a wormhole traversable but we dont know how. Warp drive is also very likely. scientists are working on ways to bend space time around ships that will allow them to glide through space shortening the distance between places. The problem with these theories is that they require either extremely large amounts of energy or require the existence of exotic matter which as of yet is not discovered. The least realistic possible way is the Hyperlanes which exists in many permutations across sci fi titles. In star wars its hyperlanes, in warhammer 40k there is a version as the webway. this is the idea that there are regions of space that are some how folds in space time that allow ships to traverse at FTL speeds. ( they could maybe but not likely exist but the cost at maintaining them would be immense and a species would be better off finding another version of ftl travel)

In Michio Kaku's book the physics of the impossible (which is easy enough for the layman to understand, so i suggest everyone interested in sci fi read it.) he classifies technology as having 3 different levels of impossibility.

Class 1 impossiblities are force fields, invisibility, phasers, teleportation, telepathy, psychokinesis, robots, ETs, starships, and anti matter / anti- universes.
these are things that impossible for us today, but they dont actually violate any known or set laws of the universe. The key to these types of technologies or discoveries is that as of right now we really dont know how to find them or build them without using exorbitant amounts of power. the idea here is that they technically can exist as long as we aren't tied to the way that they exist in the sci fi media we are used to. example Force fields will likely be a combination of 3 types of tech, magnet fields, laser fields and carbon nanotube wire together these things will likely be able deflect most types of debris or weapons we can envision now. and all exist in a way that can be created in a lab but not to what is required of it in sci fi.
* these kinds of tech are likely to be possible in the next 2 centuries*

Class 2 impossibilities are FTL, Time Travel, and Parallel Universes.
"these are technologies that sit at the very edge of our understandnig of the physical world. if they are possible at all, they might be realized on a scale of milleninia to millions of years in the future..." Except from physics of the impossible preface

Class 3 Impossibilities are perpetual motion machines and precognition
"these are technologies that violate the known laws of physics. surprisingly there are very few such impossible technologies. if they do turn out to be possible, they would represent a fundamental shift in our understanding of physics" Except from physics of the impossible preface

Time dilation is another subject and I'm not proficient enough to explain it here. the essence really boils down to what time is. this is a question that is way more complex that the simple answer most people give. and it would be easy to spend many lectures just on this subject. but the basics of it is that as you approach the speed of light you are traveling at a different speed time wise compared to others (you are technically in a different time zone) we actually have problems with satellites in space getting desynchronized from us down here because time is different up there. (due to gravity) There are really easy ways to search for this on youtube.

(side note ) What I'm most excited in is the fermi paradox and the discovery of intelligent life in the galaxy. Kurzgesagt did a fantastic 2 part video on this. its relatively easy to find on youtube. (and they also have a fantastic video on the possible deaths of the universe. ) The idea of so many species in the galaxy all having tech is harder for me to wrap around than the FTL in this game. I also have a bad habit of looking at stuff and deconstructing how they look and yelling in my head that "THATS NOT HOW IT WOULD LOOK/WORK!!!" but if anything I am a fan of the possibilities presented sci fi.

Arthur C Clarkes three laws
Clarke's first law
When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
Clarke's second law
The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
Clarke's third law
Any sufficiently advanced technology is indistinguishable from magic.

 

[LlewellynX]

I was looking into this subject for some of my own fiction projects — I didn't want everyone in my fiction to be using the same way to get around. I figured different beings would have their own unique way of tackling this problem and that would be much more interesting. So I love that Stellaris is of a like mind. The following is a graphic I found online that gives many of the current theoretical ways which might accomplish FTL. This was found at https://tauzero.aero/discoveries-log/getting-there/starship-designs/propulsion-ideas/

 

[Murmeldjuret]

At point A, in 10 minutes, a guy will shoot someone at Point B with a 0.9c projectile. You go to point B at FTL, method of FTL irrelevant, and wait for point B guy to be shot. Then you travel back to A with FTL, method of FTL irrelevant, and you arrive BEFORE point A guy has shot the projectile. What happens if you stop him? This is why FTL violates causality, regardless of means. This is a gross oversimplification, but that is how it would work according to relativity.

Why would that happen? If you wait for the guy to be shot at point B, why would you end up at point A prior to the projectile being shot?

Sounds bloody stupid.

It was an example in why violating causality is bad. Not a coherent scenario to do it if you have FTL because that requires longer timeframes.

JPL are actually working on Warp field research, so yes, they are working on "FTL".

The EM drive is a separate line of inquiry for a separate form of sub-light propulsion.

You are very correct, NASA is actually working on warp as well as EM. My bad.

 

[TheBeautifulVoid2]

No, you wouldn't, because you are not travelling faster than light - you are warping space to make it appear like you are, but you're not.

These two statements are synonyms, relativistically speaking.

Does your scenario also apply to objects that are simply very far away communicating (and not exclusively to a scenario with time dilation)?

Hi Person012345! I haven't seen you before, so welcome to the Stellaris forums if you're new.

If two objects are very far away but are not moving with respect to one another then there is no time dilation. One day on Earth will also be one day on the James T. Kirk. This means that yes, in a scenario where everything in the universe is static, FTL does not violate causality.

Does that answer the question?

 

[Person012345]

Hi Person012345! I haven't seen you before, so welcome to the Stellaris forums if you're new.

If two objects are very far away but are not moving with respect to one another then there is no time dilation. One day on Earth will also be one day on the James T. Kirk. This means that yes, in a scenario where everything in the universe is static, FTL does not violate causality.

Does that answer the question?

Maybe. I'm sure I've seen the "ftl communication violates causality" thing applied to communications over long distances as well though.

Also I've been here over 6 years

 

[Person012345]

As an object or information travels closer to the speed of light it takes more energy to move an object that gains more mass. The faster something goes the heavier it gets. The speed of light makes some something infinitely heavy and requires infinite energy to propel it. That is why the speed limit. An object is just information and vice versa. So the speed limit of information.

The only time information can travel faster than light is during inflation. It is called propagation of information. As long as you are not transmitting information like light, something can happen faster than light. The edges of the universe moved faster away from each other than the speed of light only because they could not "see" each other. That is a very basic description of inflation.

Again, you're just inserting "information" there. That's not a thing. As I already told you, information is not an actual thing that actually travels anywhere. It's a state, carried by something usually, but just a state. There is no law to the best of my knowledge that says that information can't get places faster than light inherently. I already understand how the speed of light works, it applies to energy and matter. The things that information is carried on. And in the case of tachyons (which are not impossible as far as we know), or perhaps some other tech based on expanding space itself then it would be carriable faster than light and there's no law preventing this.

All I'm getting from you is that the original post I was asking about was wrong and you keep inserting "information" into rules that don't mention information in order to defend it. Which may not be the case, it's just what I'm getting from your lack of an explanation.

 

[Bragi]

As an object or information travels closer to the speed of light it takes more energy to move an object that gains more mass. The faster something goes the heavier it gets. The speed of light makes some something infinitely heavy and requires infinite energy to propel it. That is why the speed limit. An object is just information and vice versa. So the speed limit of information.

The only time information can travel faster than light is during inflation. It is called propagation of information. As long as you are not transmitting information like light, something can happen faster than light. The edges of the universe moved faster away from each other than the speed of light only because they could not "see" each other. That is a very basic description of inflation.

You might referring to "data" instead of "Information". As mentioned before, information is merely a state where you as a human being can decifer/interprete any kind of data into useful parts -> information.
Data indeed can be transmitted at light speed.

 

[Botox]

Pretty interesting how this thread literally exploded.

As far as I understood it, FTL is not possible without breaking serveral "laws" of physics, including Einstein's theory of relativity as you can not travel faster then light and you can not separate time from space or the other way around, keyword beeing spacetime. That includes the ability to travel backwards in time, as you would need to travel faster then light in the "normal" universe which you cant, this includes data or information that can also not travel faster then lightspeed, so no quantum entagled data transfer.

I - in my limited unterstanding of this matters - always bypass this by somewhat accepting that spacetime can be bypassed by some sort of underlying space (in sci fi often called hyperspace, warp or something) which you can enter and leave and where the normal rules of the speed of light do not stand in the way or limit the possibility of it. So instead of breaking Einsteins heritage you would say "Ok, not possible here but if I leave this plane/sphere I can do it".

Works pretty well for me (and my head doesnt explode) as it would otherwise be damn boring to play a 4X in space

 

[Barcode180]

Sigh.

There is a difference between something being a presently-insurmountable engineering challenge, like those were at one time, and a physical impossibility.

Physics is the process of understanding the universe. The more we learn, the more we appreciate what the universe permits and what it does not. We do not invent these rules: we discover them.

Sometimes the rules we discover are positive in nature: if you do X then Y will happen. For example, we know that a wire moving through a magnetic field will generate an electric current. We have used this to create electrical generators, which power the device you're reading this with.

We have also discovered some rules which are negative in nature: you cannot cause X to occur under any circumstances. For example, we know that a neutron travelling through an electrical field will not have its course changed by that field.

Sometimes, when engineers say that something is not possible, they mean that we have not discovered a positive law that tells us how we can achieve that thing. On the other hand, when physicists say that something is impossible we mean that we have discovered a negative law which states that it will never happen under any circumstances because nature explicitly forbids it. I think this is the cause of your confusion.

I appreciate that you would like to believe that you live in a universe of infinite possibility where all things could one day happen. You will normally find that physicists feel the same way, and are equally optimistic. As a profession we tend to assume that everything which isn't explicity forbidden by nature will one day happen; we certainly get really disappointed when petty things like economics and engineering prevent us from achieving our dreams.

However, please pay physics a little respect. When we say that something has been studied and has been found to be impossible, trust us.

/thread



I feel that you might have misheard something somewhere. Neutrinos are not tachyons.

There was an experiment at CERN which claimed that a tau neutrino travelled faster than light, but that was later found to be due to an error in the readings. Is that the incident you're referring to?

No I am referring to the experiments that are currently ongoing with particles thought to have negative energy and very small mass (which they think neutrinos are one of). Not the outdated CERN experiment. Just because something hasn't been proven yet doesn't mean it can't exist or is impossible. With thinking like that we probably would still be wondering how to make fire.

People who say that you can't travel at, or faster than the speed of light are going to have a lot of egg on their face similar to the people who said the Earth was flat. If anything people should refer to scientific philosophy when it says that there are the current theories with what are considered current "laws", but every once in a while comes new evidence that isn't explained by the current theories and then new theories develop which replace the old ones. This has happened multiple times throughout history, and I don't think it will be the last.

 

[Jorgen_CAB]

I think that IF Warp was possible you could avoid the time machine problem with the following thought experiment.

The Twin-Paradox for example state that someone leaving Earth for a round trip of about four light years and travelling at 0.8C would age about 6 years while anyone at Earth would have aged about 10 years. The problem is that the crew on the ship would always see Earth as ageing less than they do because time on Earth would appear to slow down for them as well as time on the ship appear to slow down from Earth.

Now.. the thing is, it is has to do with whom are doing the actual acceleration and deviate from the other in velocity that is actually experience slower time flow (they also experience less space)... in my opinion there are no reason the same would not be true when applying a technology such as Warp.

If you for example would take a ship and accelerate it up to 0.8C and drive it away from Earth and let it run for 10 years (from Earths perspective) then time have only passed 6 years on the ship but the ship only think that about 4 years passed on Earth. If you launched a probe from the ship at Warp speed and arrived in Earth space at that point the probe would NOT end up at Earth when it had only done four rotation around the sun but at the current time frame of ten rotations.
My reasoning are that the actual space time are not the same as the one you are observing when you are moving at relativistic speeds and it is the one who accelerated in relation to the other who will have the wrong impression of time. What you observe are not the same thing as what actually IS the current space and time at a specific location, for the same reason you will not get the paradox of the twins.

That would preserve the problem of causality if that was the case.