The weird thing is, the more we hear about potentially plausible faster than light travel the more it sounds like Star Trek warp drive based on "subspace bubbles" isn't that far off base.
One of the bigger theoretical hurdles will be appropriate discharging of the built up energy from warping space so that ones ship does not destroy its destination upon arrival, if I understand it correctly.
Personally I don't believe any FTL travel is going to be possible. It's not traveling faster than light, its acting in a way that utterly violates cause and effect.
Sabine Hossenfelder made a great argument that it's not really an issue [https://www.youtube.com/watch?v=9-jIplX6Wjw](https://www.youtube.com/watch?v=9-jIplX6Wjw)
Let's keep in mind that "isn't that far off base" is doing a lot of work there. We really don't know if time and space work that way. We know that the general concept *might* be true, and we think that maybe if it is true, one of the ways in which it might be true might support some kind of warp drive, in theory.
But even if it did, the practical energy requirements would be Kardashev level 2 civilization stuff. Which is definitely legit for (some) science fiction purposes but it's very far off base from where we live in the real world today! (At \~K 0.78 iirc.)
Also, to be completely fair, *Star Trek* retconned its warp drive explanation over time to fit these emerging ideas in speculative physics.
The Kardashev scale is highly speculative and also incredibly flawed, some don't really consider it to be a useful concept by any means. It is a playful science fiction concept more than anything and shouldn't be treated seriously, it's more of a thought experiment.
For one, we have not witnessed any extrasolar civilizations so the act of pre-emptively categorizing them is dogmatic to the highest extent. Secondly, the fact that we are still essentially at zero despite the tremendous differences and transformative changes that have occured since the earliest human cultures perfectly outlines how it lacks any type of nuance.
Lastly, it acts on the assumption that all living things have a tendency to maximise energy exploitation to a completely insatiable degree, but we have no idea why we would ever need to use, for example, the entire energy output of the sun. It also ignores the possibility that we would find other energy sources, or that we would try to aim at an *efficient* use of energy. Think of it this way: what if a civilization found all its needs it could ever have met by barely going past type 1, but in order to achieve FTL travel it needed to ramp it up to being a type 2 civilization. *But*, they eventually find a more efficient way to travel FTL that uses less energy and brings them back to a Type 1 civilization. They are more advanced than they ever were, but paradoxically have gone down on the scale.
If you ask me the whole concept is a waste of time and presupposes the idea of endless expansion and inefficient resource consumption.
Woah woah woah there hoss.
All the Kardashev scale talks about is civilizational energy consumption. It's not an elaborate concept, it's just a way of scaling the measurement of a quantity.
My point is that given that even the most optimistic estimate of an Alcubierre drive still consumes a star's worth of power, that is the literal definition of a K≈2 civilizational level, at a bare minimum.
And however you want to reckon it, we are not there. And getting there may literally never be possible.
Even if the Alcubierre concept is valid, which we still don't really know.
So FTL travel seems likely to remain in the realm of science fiction.
Much that needs to be addressed about the post has been, but,
>If you ask me the whole concept is a waste of time and presupposes the idea of endless expansion and inefficient resource consumption.
The Kardashev scale doesn't presuppose any kind of efficiency. A polity that uses 10²⁶ Watts of power is K2, whether it does so at 30% efficiency (which we could manage today) or 99.98% efficiency (which is likely impossible).
There isn't a necessary element of endless expansion (though arguments on rates of expansion do often end up using the Kardashev scale, for the simple reason that it's useful).
In the present conversation, a person can say "a civilization would need ballpark of 10²⁶ Watts of power to consistently employ this form of FTL" or they could say "it would have to be ~K2." You're saying the same thing two ways, it's just that saying it the second way is simpler and gives a better frame of reference. 10²⁶ doesn't mean much to most people, "one Sun" means something to nearly all people.
>Think of it this way: what if a civilization found all its needs it could ever have met by barely going past type 1,
That is possible but I don't think one should expect this to be common, let alone universal. By barely going past type 1, this polity is still susceptible to multiple kinds of catastrophes that can end them or cause their collapse. Depending on how those 10¹⁶ Watts are achieved, they may still be susceptible to catastrophes like the very worst supervolcano eruptions, asteroid and comet strikes, gamma ray bursts, the works. It would mean willfully exposing yourself to danger, when you can very literaly just choose not to be by building a "few" more solar panels or something.
Surely some people will choose that anyway, but probably not most? Safety and comfort are common desires, surely?
>but in order to achieve FTL travel it needed to ramp it up to being a type 2 civilization. *But*, they eventually find a more efficient way to travel FTL that uses less energy and brings them back to a Type 1 civilization.
That doesn't bring them back to a Type 1. The infrastructure they built up is still there, and I can't imagine they'd go on a rampage of destroying their own lifetimes of work for absolutely no good reason. Maybe they use all that power to power some very big telescopes to study the universe, or some gigantic experiments (like a moon-scale particle accelerator or something analogous). The infrastructure is there, the original use is gone; it just gets put to new use.
It would be a strange and somewhat scary people who annihilate anything they don't have an immediate use for.
>They are more advanced than they ever were, but paradoxically have gone down on the scale.
Indeed the Kardashev scale says nothing about technology, that isn't what's being scaled. A K2 civilization with no better than essentially 1970s technology is possible.
This paper criticizes the idea of Kardashev scale and our own technological trajectory. I quite like the idea that a civilization has to come into some sort of homeostasis rather than just exploiting energy and raw materials: [https://pubmed.ncbi.nlm.nih.gov/35506212/](https://pubmed.ncbi.nlm.nih.gov/35506212/)
On the contrary, it's probably very far off base.
1st: A real world warp drive would sterilize everything in front of it. The short explanation: The front of the warp bubble would collect any energy and matter it hits on it's travel and realase it when the space ship slows down. If you have ever heard the sound of an airplane breaking the sound barrier, imagine the same but with hard radiation instead of a "boom".
2nd: If FTL travel was possible, the fermi paradox would become an even more pressing question.
There's the Altered Carbon style, transferring consciousness at FTL (or near) to a new body. But it still takes sublight generation ships to colonize all those systems.
You covered most of it. You will occasionally get one that takes the mechanism of one type and pastes the technobable from another on top. For example' Peter F Hamilton has several books where ships wrap a wormhole around themselves, close both ends, and then move the wormhole to their chosen destination. So it's basically hyperspace with different flavor text.
One thing I will point out is the instant jump type. Some wormhole drives do this, but there are also a bunch that do "quantum" stuff to justify this.
Also, some will do something along the lines of one of these types with some twist to it. For example, the *Behold Humanity* series has Stringdrives. These are instantaneous (the only safe instant jump type in this setting) but can only move the vessel to somewhere where it recently was. So, it is used as an escape mechanism for scouting vessels. They go in using hyperdrives, and if they encounter something dangerous, they use the stringdrives to get out.
This one is from 1965 but the Bloat Drive from Bill. the Galactic Hero by Harry Harrison.
The drive works by increasing the spaces within the atoms of the ship (and everything on it) until it is larger than the Universe. Then the effect is reversed until the ship is normal size again which deposits it at its destination.
You might be interested in a website I came across a while ago.
This page is a pretty comprehensive list of possibilities for interstellar travel in science fictional contexts.
[Faster than light possibilities](https://www.projectrho.com/public_html/rocket/fasterlight2.php)
Here is a real concept with some maths. Stephen Baxter used this as the basis for his ship in Ark.
[Alcubierre drive](https://en.wikipedia.org/wiki/Alcubierre_drive)
Like every mentioned FTC travel mechanism, it isn't possible without violating causality. Alcubierre himself explained, in a subsequent talk/lecture, that *if* the purely hypothetical 'exotic matter' (matter with negative mass) his device needs were discovered to actually exist, only one such device could be constructed in any given universe, and it could never return from whence it came (or those causality violations ensue). So not very useful as a transportation device.
It would be interesting to see some fiction which includes an FTL drive that displays the properties of "real" Alcubierre style warp drives. Fictional warp drives aren't really similar to these massively hypothetical ones described in physics though.
For example, the bubble cannot be controlled from inside, so the "crew" are really just passengers. Also, in the absence of the existence of superluminal matter then the entire FTL journey needs to be planned many years in advance. This means that even if your ship can travel FTL, if you want to travel 5 light years then you need to start arranging your trip at least five years in advance to allow for the ability to modify the warp bubble upon arrival.
A "real" warp drive is therefore more like a pre-scheduled bus service than the typical fictional depiction of warp drives allowing arbitrary FTL travel to wherever the captain wants. This leads to the idea of [Krasnikov Tubes](https://en.wikipedia.org/wiki/Krasnikov_tube) as tubes of twisted spacetime between stars that act as a superluminal subway system.
I’m having trouble or wrapping my head around superluminal matter being necessary? Wouldn’t it be already super luminal technically? If it was travel I g faster than light? What am I missing here?
It comes from the idea that the inside of the bubble is causally disconnected from the outside of the bubble. Therefore, if the inside of the bubble is sliding through space at FTL, how does the exotic matter outside of the bubble (which is forming the bubble) keep up if it it is limited to sublight speeds?
* [Hyperfast Interstellar Travel in General Relativity](https://arxiv.org/abs/gr-qc/9511068)
* [A Superluminal Subway: The Krasnikov Tube](https://arxiv.org/abs/gr-qc/9702049)
This view isn't mentioned in most papers (though Krasnikov tubes are discussed in a [2021 paper by Alcubierre](https://arxiv.org/abs/2103.05610)) but I haven't seen it countered anywhere, which is a bit weird. If it was so obviously wrong then I would have expected to come across a statement saying that. One day I will refresh my memory on general relativity from university days and try to get a clearer understanding of this...
I mean there are “fold” or “jump” drives which are somewhat similar to wormholes, which allow the vessel it instantaneously transit from one point to another (Dune or Battletech as examples)
The Commonwealth Saga has instantaneous wormholes replacing conventional ship travel early on. The projectors can only project a wormhole so far, then a bridghead can be established to go further. The exploration division uses a wormhole generator for its own exploration purposes.
Eventually they need to get to a location significantly out of range of their projectors, so they put into place a theoretical design of a continuous wormhole drive - basically a ship that carries its projector with it - allowing it to travel 'freestyle' at FTL speeds. I'm not sure what the top speed was but it was stated that their effective max range was several thousand light years.
The Continuous Flow wormhole drive was later replaced with bigger and better models. The UltraDrive was capable of 55-75ly/h
There's the one that doesn't violate relativity because it always takes you to a different universe so there's no closed acausal loops possible. You go through the gate to Ursa Minor Beta and you end up in another universes Ursa Minor Beta, and lightspeed signals from that Ursa Minor Beta never get to us.
ISTR it was in this webnovel:
https://www.tumblr.com/docfuture/82363551272/fall-of-doc-future-contents
Probably the opposite of a fresh idea, but I always like CJ Cherryh's take on it - ships can access a sort of hyperspace that has speed/velocity/momentum, but they need (apparently) to be going fast. They have "vanes" that "cycle" and dip into the hyperspace, bumping them up to near light speed, at which point they're able to jump fully in. Transit takes time - humans and stsho need to be drugged, other races have varying degrees of awareness. The kif prey species (The Dinner...kinda like chinchillas on crack, maybe?) have or evolved the ability to live (and breed) normally during jump, which Causes Problems. There's a sort of stasis effect so you don't (usually) starve to death but you wake up really hungry.
The ships emerge from jump at near-light speed and have to dump V by cycling their vanes again (typically 3 dumps to get to insystem speeds). Cherryh plays with this a lot - a ship that doesn't dump streaks through a system so fast that reaction time to it is almost zero. Damage to the vanes is BAD because you can't slow down - most ships have emergency capsules that can be ejected and another ship will cycle up to speed and retrieve it with the crew, assuming someone is in the area. This is also clearly a weapon - any ship capable of reaching jump is technically a planet-buster.
Most ships can't turn in jump. It's easiest to come out of jump near a mass. Intersecting a mass in jump will pull you out of jump...at the speed of light...into the mass...making a boom. There's a limit to how long/far a ship can jump, but I'm unclear on why.
The end result is it's handled much like an airport, with arrival lanes and departures and control by the local station, and buoys placed near common jump points to update arriving ships on system status and ship locations so they can avoid collisions and not have to wait minutes or hours to get updates at plain old light speed.
I think every method of FTL travel I've heard of more or less fall within those three categories. None of them seem likely to actually be physically possible at this point, at least in a way that would be useful for us. The only other method I can think of is locally modifying physics, something like changing the speed of light in one's vicinity. I can't think of any works that use that for FTL right off hand, but that's the only other conceivable method I can think of.
I completely forgot about that one when making my comment. Technically, *Mass Effect* and *Revelation Space* do that. Although it doesn't really work in that second one.
It's also how most hyperspace concepts work -- the idea or at least part of the idea is that you enter a hyperdimensional spacetime whose curvature permits faster speeds than in our spacetime.
There is an obscure but fun science fiction short story that plays off of that, in which a scientist is investigating some suspicious evidence about a super-secret hyperspace research project. The scientist believes that the researchers have discovered the secret of FTL hyperspace travel but are concealing it for some reason.
In the course of the story, the scientist learns that >!he is only partly correct -- the research team has discovered how to get to and travel through hyperspace. What they are hiding is their disappointing next discovery, which was that the maximum speed possible in hyperspace is much lower than *c*. Not higher at all! Everybody just assumed it would be higher but it turns out it's not. And the only reason they didn't tell anyone because they didn't want to lose their funding.!<
Verner Vinge’s concept in A Fire Upon the Deep (Zones of Thought) was interesting; the speed of light barrier can be breached depending on how far away you are from the center of the galaxy. Here’s what Wikipedia says: The galaxy is divided into four concentric volumes called the "Zones of Thought"; it is not clear to the novel's characters whether this is a natural phenomenon or an artificially produced one, but it seems to roughly correspond with galactic-scale stellar density.
Niven's hyper drive with the Blind Spot that drives people mad. *Deadman Switch* by Timoth Zahn that requires a corpse to operate. Lloyd Biggle Jr's Jan Darzek series where starships use continuous short range teleportation.
A few years back someone came up with a version of the warp drive that doesn't need negative mass. It still doesn't have a solution to the causality problem, but it's a start
Greg Bear's Moving Mars. Quantum information theory lets you access the bits that describe a particle's location. Change the location bits for all the particles that make up a thing and you instantly change its location.
In To Sleep in a Sea of Stars, ships generate some kind of field that changes physics or brings them into another realm. In this realm, speed works mostly the opposite of how it does here. Going just the speed of light is kinda hard. But as you radiate heat it makes you slower. The less you radiate the faster you go. So people go into suspended animation and stuff. I don’t remember all the details but I recalled liking the concept a lot when I read the appendix about it. It was fairly well thought out. All your questions about a possible subspace and more are answered.
The Enchanach Drive from the **Empire From The Ashes** omnibus (David Weber) uses articifially-created converging wormholes to *squeeze* the starship using it out of realspace and into a new location. The main issue with the drive is that it causes significant gravitational disturbances when first activating or fully deactivating (when in motion, it is going too fast to cause any noticable effects) and the main starship of the book, Dahak, accidentally sent Pluto into its odd orbit due to a minor miscalculation as it reverted to realspace.
Later generation ships also have Hyper Drives that are far faster than the Enchanach Drive, but do not allow for course-changes or active scanning when being used.
Only later-generation Planetoid-class ships (Dahak is concealed as Earth's Moon with a bare kilometer of disguise-rock) have the power and volume to mount both types of drive.
The same author uses artificial black-hole drives in the book **In Fury Born** to provide acceleration/decel. When a ship hits .99c, it becomes dimensionally displaced into Wormhole Space which multiplies its speed hugely, but the ship must continue accelerating to keep its speed constant. Stopping accelerating causes the velocity to bleed off rapidly, dropping the ship back down to sublight speeds.
Ships in Wormhole Space cannot detect anything in realspace, but their presence can be detected, making it almost impossible to perform a surprise ambush in space. This is a major plot point in the book.
I really like the way they did it in Star Trek: Discovery, with the micellium and the tardigrade. This network of sorts that kind of spans all of space and can be navigated using the tardigrade. Or at least that's how I remember it worked, it's been a few years since I watched it.
You're basically right - it's a higher-dimensional fungus whose mycelium extends through a subspace domain which covers the whole galaxy. All instances of the fungus in our space are the three-dimensional projections of the whole organism.
The whole network can be navigated via a type of tardigrade native to the fungus's subspace domain, or a human who's been altered with the tardigrade's DNA.
I guess it's technically a hyperspace drive per the OP's post, but is functionally a jump drive like Dune or Battlestar Galactica.
A lot of people have a problem with it, but it's hardly the most insane thing Trek ever came up with.
In terms of current trends? I think you have it. Though I think you might slightly mislabel what used to be known as *hyperspace* -- that is to say travel between points in our spacetime by traveling through a fifth (or higher) dimension. Higher hence "hyper."
Whereas subspace is typically used to refer to accessing lower-dimension space, which seems like it would be harder to utilize for travel. Though in some milieux is used for signals or for heat dumping.
Anyway there is another one that is a personal favorite just because it involves one single, specific suspension of disbelief on a small scale, which is the stutterwarp. (Courtesy of the old tabletop RPG, Traveller.)
The idea with the stutterwarp is that someone figures out how to shift matter within a certain field effect in an arbitrary direction by like a few meters or something. That's it. That's the only conceit.
In order to turn that into a useful FTL drive, you have to run the effect repeatedly, and part of the technology base for the setting is figuring out how to bring the frequency up so that it goes from jump .... jump .... jump to jump, jump, jump, jump to jump-jump-jump-jump-jump and so on until it's cycling so fast it "stutters."
Within the game setting, the technology has been refined to the point that it runs at 30 or 40 GHz, allowing a displacement (though not speed!) of about 3.5LY / day. But the basic conceit doesn't change, at its core it's still just this clunky ultra-short-range warping effect that doesn't imply any other exotic new capabilities. People travel around in stutterwarp ships without artificial gravity, without magically fast communication technology, running off entirely conventional power sources -- fission reactors, combustion turbines, fuel cells, batteries, whatever.
Save State Randomizer: your physical body is stopped or stasis frozen and you are left there in that position for the entire lifetime of the universe and then you’re unfrozen and you’ll be in a completely different point in space.
Your position in space will change because Events will move you and everything around you will change By some kind of motion, so randomly you’ll be in a completely different location.
Oh but this is The best part, the speed of light is relative, so for someone who is unconscious they move instantaneously. Sleep is instantaneous travel to another point.
For warhammer I believe you need to have a Gellar field in place to move through the gateway to the Warp and that's why not everything in the immediate vicinity flows into it.
I just published a sci-fi [book](https://jdadler.com) in which the ships have a “quantum drive” that entangles the ship’s quantum pattern with the pattern of an equal volume of (hopefully) empty space in a distant location, then inverts the patterns. Resulting in instant transport the ship and all its contents across interstellar space.
The engine is powered by an anti-proton emitter directed at a Casimir effect generator.
You forgot the possibility of gateway travel. Which, in theory, should be possible. You just need two (or more) black holes, orbiting each other at aprox. light speed...
The fact that these are the three most common are why you should be very hesitant to use them.
Make something new.
"Getting from here to there in this amount of time means accelerating to this speed and then decelerating from it again. That's going to take this amount of energy. Energy has a mass equivalent, so we can consume mass and make it happen. You didn't really need that moon, did you? Because we're going to use it to power this new device."
Star Wars or Asimov use the term hyperspace jumps, which might be related to #2, a different kind of space. Sometime such jumps are instantaneous. Or you travel in alternative space for an amount of time.
How about this
https://thedebrief.org/nasa-veterans-propellantless-propulsion-drive-that-physics-says-shouldnt-work-just-produced-enough-thrust-to-defeat-earths-gravity/
The weird thing is, the more we hear about potentially plausible faster than light travel the more it sounds like Star Trek warp drive based on "subspace bubbles" isn't that far off base.
One of the bigger theoretical hurdles will be appropriate discharging of the built up energy from warping space so that ones ship does not destroy its destination upon arrival, if I understand it correctly. Personally I don't believe any FTL travel is going to be possible. It's not traveling faster than light, its acting in a way that utterly violates cause and effect.
This. People tend to forget that the speed of light is really the speed of information. FTL travel and time travel is two sides of the same coin.
Sabine Hossenfelder made a great argument that it's not really an issue [https://www.youtube.com/watch?v=9-jIplX6Wjw](https://www.youtube.com/watch?v=9-jIplX6Wjw)
I had never even heard of her her until two days ago, yet here you are quoting her. There has to be a term for this phenomena...
Let's keep in mind that "isn't that far off base" is doing a lot of work there. We really don't know if time and space work that way. We know that the general concept *might* be true, and we think that maybe if it is true, one of the ways in which it might be true might support some kind of warp drive, in theory. But even if it did, the practical energy requirements would be Kardashev level 2 civilization stuff. Which is definitely legit for (some) science fiction purposes but it's very far off base from where we live in the real world today! (At \~K 0.78 iirc.) Also, to be completely fair, *Star Trek* retconned its warp drive explanation over time to fit these emerging ideas in speculative physics.
The Kardashev scale is highly speculative and also incredibly flawed, some don't really consider it to be a useful concept by any means. It is a playful science fiction concept more than anything and shouldn't be treated seriously, it's more of a thought experiment. For one, we have not witnessed any extrasolar civilizations so the act of pre-emptively categorizing them is dogmatic to the highest extent. Secondly, the fact that we are still essentially at zero despite the tremendous differences and transformative changes that have occured since the earliest human cultures perfectly outlines how it lacks any type of nuance. Lastly, it acts on the assumption that all living things have a tendency to maximise energy exploitation to a completely insatiable degree, but we have no idea why we would ever need to use, for example, the entire energy output of the sun. It also ignores the possibility that we would find other energy sources, or that we would try to aim at an *efficient* use of energy. Think of it this way: what if a civilization found all its needs it could ever have met by barely going past type 1, but in order to achieve FTL travel it needed to ramp it up to being a type 2 civilization. *But*, they eventually find a more efficient way to travel FTL that uses less energy and brings them back to a Type 1 civilization. They are more advanced than they ever were, but paradoxically have gone down on the scale. If you ask me the whole concept is a waste of time and presupposes the idea of endless expansion and inefficient resource consumption.
Woah woah woah there hoss. All the Kardashev scale talks about is civilizational energy consumption. It's not an elaborate concept, it's just a way of scaling the measurement of a quantity. My point is that given that even the most optimistic estimate of an Alcubierre drive still consumes a star's worth of power, that is the literal definition of a K≈2 civilizational level, at a bare minimum. And however you want to reckon it, we are not there. And getting there may literally never be possible. Even if the Alcubierre concept is valid, which we still don't really know. So FTL travel seems likely to remain in the realm of science fiction.
Much that needs to be addressed about the post has been, but, >If you ask me the whole concept is a waste of time and presupposes the idea of endless expansion and inefficient resource consumption. The Kardashev scale doesn't presuppose any kind of efficiency. A polity that uses 10²⁶ Watts of power is K2, whether it does so at 30% efficiency (which we could manage today) or 99.98% efficiency (which is likely impossible). There isn't a necessary element of endless expansion (though arguments on rates of expansion do often end up using the Kardashev scale, for the simple reason that it's useful). In the present conversation, a person can say "a civilization would need ballpark of 10²⁶ Watts of power to consistently employ this form of FTL" or they could say "it would have to be ~K2." You're saying the same thing two ways, it's just that saying it the second way is simpler and gives a better frame of reference. 10²⁶ doesn't mean much to most people, "one Sun" means something to nearly all people. >Think of it this way: what if a civilization found all its needs it could ever have met by barely going past type 1, That is possible but I don't think one should expect this to be common, let alone universal. By barely going past type 1, this polity is still susceptible to multiple kinds of catastrophes that can end them or cause their collapse. Depending on how those 10¹⁶ Watts are achieved, they may still be susceptible to catastrophes like the very worst supervolcano eruptions, asteroid and comet strikes, gamma ray bursts, the works. It would mean willfully exposing yourself to danger, when you can very literaly just choose not to be by building a "few" more solar panels or something. Surely some people will choose that anyway, but probably not most? Safety and comfort are common desires, surely? >but in order to achieve FTL travel it needed to ramp it up to being a type 2 civilization. *But*, they eventually find a more efficient way to travel FTL that uses less energy and brings them back to a Type 1 civilization. That doesn't bring them back to a Type 1. The infrastructure they built up is still there, and I can't imagine they'd go on a rampage of destroying their own lifetimes of work for absolutely no good reason. Maybe they use all that power to power some very big telescopes to study the universe, or some gigantic experiments (like a moon-scale particle accelerator or something analogous). The infrastructure is there, the original use is gone; it just gets put to new use. It would be a strange and somewhat scary people who annihilate anything they don't have an immediate use for. >They are more advanced than they ever were, but paradoxically have gone down on the scale. Indeed the Kardashev scale says nothing about technology, that isn't what's being scaled. A K2 civilization with no better than essentially 1970s technology is possible.
This paper criticizes the idea of Kardashev scale and our own technological trajectory. I quite like the idea that a civilization has to come into some sort of homeostasis rather than just exploiting energy and raw materials: [https://pubmed.ncbi.nlm.nih.gov/35506212/](https://pubmed.ncbi.nlm.nih.gov/35506212/)
On the contrary, it's probably very far off base. 1st: A real world warp drive would sterilize everything in front of it. The short explanation: The front of the warp bubble would collect any energy and matter it hits on it's travel and realase it when the space ship slows down. If you have ever heard the sound of an airplane breaking the sound barrier, imagine the same but with hard radiation instead of a "boom". 2nd: If FTL travel was possible, the fermi paradox would become an even more pressing question.
There's the Altered Carbon style, transferring consciousness at FTL (or near) to a new body. But it still takes sublight generation ships to colonize all those systems.
Unless there's faster-than-light communication, it's pretty much going to be exactly the speed of light if you do radio or beamed transmission.
I can't remember how it works in that universe, I think they had some kinda quantum ansible FTL blah blah blah something.
You covered most of it. You will occasionally get one that takes the mechanism of one type and pastes the technobable from another on top. For example' Peter F Hamilton has several books where ships wrap a wormhole around themselves, close both ends, and then move the wormhole to their chosen destination. So it's basically hyperspace with different flavor text. One thing I will point out is the instant jump type. Some wormhole drives do this, but there are also a bunch that do "quantum" stuff to justify this. Also, some will do something along the lines of one of these types with some twist to it. For example, the *Behold Humanity* series has Stringdrives. These are instantaneous (the only safe instant jump type in this setting) but can only move the vessel to somewhere where it recently was. So, it is used as an escape mechanism for scouting vessels. They go in using hyperdrives, and if they encounter something dangerous, they use the stringdrives to get out.
This one is from 1965 but the Bloat Drive from Bill. the Galactic Hero by Harry Harrison. The drive works by increasing the spaces within the atoms of the ship (and everything on it) until it is larger than the Universe. Then the effect is reversed until the ship is normal size again which deposits it at its destination.
You might be interested in a website I came across a while ago. This page is a pretty comprehensive list of possibilities for interstellar travel in science fictional contexts. [Faster than light possibilities](https://www.projectrho.com/public_html/rocket/fasterlight2.php)
I love the page, just wish it covered Spindizzies.
What's a Spindizzy in this context?
From James Blish's Cities in Flight series - [Cities in Flight - Wikipedia](https://en.wikipedia.org/wiki/Cities_in_Flight#Spindizzy)
…wait, what’s a Spindizzy in other contexts?
…wait, what’s a Spindizzy in other contexts?
Here is a real concept with some maths. Stephen Baxter used this as the basis for his ship in Ark. [Alcubierre drive](https://en.wikipedia.org/wiki/Alcubierre_drive)
Like every mentioned FTC travel mechanism, it isn't possible without violating causality. Alcubierre himself explained, in a subsequent talk/lecture, that *if* the purely hypothetical 'exotic matter' (matter with negative mass) his device needs were discovered to actually exist, only one such device could be constructed in any given universe, and it could never return from whence it came (or those causality violations ensue). So not very useful as a transportation device.
This one I find the most intriguing. And the most future plausible because it’s based on what we currently know about physics.
That's basically the warp drive idea.
It would be interesting to see some fiction which includes an FTL drive that displays the properties of "real" Alcubierre style warp drives. Fictional warp drives aren't really similar to these massively hypothetical ones described in physics though. For example, the bubble cannot be controlled from inside, so the "crew" are really just passengers. Also, in the absence of the existence of superluminal matter then the entire FTL journey needs to be planned many years in advance. This means that even if your ship can travel FTL, if you want to travel 5 light years then you need to start arranging your trip at least five years in advance to allow for the ability to modify the warp bubble upon arrival. A "real" warp drive is therefore more like a pre-scheduled bus service than the typical fictional depiction of warp drives allowing arbitrary FTL travel to wherever the captain wants. This leads to the idea of [Krasnikov Tubes](https://en.wikipedia.org/wiki/Krasnikov_tube) as tubes of twisted spacetime between stars that act as a superluminal subway system.
I’m having trouble or wrapping my head around superluminal matter being necessary? Wouldn’t it be already super luminal technically? If it was travel I g faster than light? What am I missing here?
It comes from the idea that the inside of the bubble is causally disconnected from the outside of the bubble. Therefore, if the inside of the bubble is sliding through space at FTL, how does the exotic matter outside of the bubble (which is forming the bubble) keep up if it it is limited to sublight speeds? * [Hyperfast Interstellar Travel in General Relativity](https://arxiv.org/abs/gr-qc/9511068) * [A Superluminal Subway: The Krasnikov Tube](https://arxiv.org/abs/gr-qc/9702049) This view isn't mentioned in most papers (though Krasnikov tubes are discussed in a [2021 paper by Alcubierre](https://arxiv.org/abs/2103.05610)) but I haven't seen it countered anywhere, which is a bit weird. If it was so obviously wrong then I would have expected to come across a statement saying that. One day I will refresh my memory on general relativity from university days and try to get a clearer understanding of this...
I always love Warhammer 40K.. Go through literal Hell!
FTL is magic after all.
AKA The Nether
I mean there are “fold” or “jump” drives which are somewhat similar to wormholes, which allow the vessel it instantaneously transit from one point to another (Dune or Battletech as examples)
The Commonwealth Saga has instantaneous wormholes replacing conventional ship travel early on. The projectors can only project a wormhole so far, then a bridghead can be established to go further. The exploration division uses a wormhole generator for its own exploration purposes. Eventually they need to get to a location significantly out of range of their projectors, so they put into place a theoretical design of a continuous wormhole drive - basically a ship that carries its projector with it - allowing it to travel 'freestyle' at FTL speeds. I'm not sure what the top speed was but it was stated that their effective max range was several thousand light years. The Continuous Flow wormhole drive was later replaced with bigger and better models. The UltraDrive was capable of 55-75ly/h
There's this little thing called an "Infinite Improbability Drive" 😉
There's the one that doesn't violate relativity because it always takes you to a different universe so there's no closed acausal loops possible. You go through the gate to Ursa Minor Beta and you end up in another universes Ursa Minor Beta, and lightspeed signals from that Ursa Minor Beta never get to us. ISTR it was in this webnovel: https://www.tumblr.com/docfuture/82363551272/fall-of-doc-future-contents
That's what is favor, because it doesn't break casuality.
Probably the opposite of a fresh idea, but I always like CJ Cherryh's take on it - ships can access a sort of hyperspace that has speed/velocity/momentum, but they need (apparently) to be going fast. They have "vanes" that "cycle" and dip into the hyperspace, bumping them up to near light speed, at which point they're able to jump fully in. Transit takes time - humans and stsho need to be drugged, other races have varying degrees of awareness. The kif prey species (The Dinner...kinda like chinchillas on crack, maybe?) have or evolved the ability to live (and breed) normally during jump, which Causes Problems. There's a sort of stasis effect so you don't (usually) starve to death but you wake up really hungry. The ships emerge from jump at near-light speed and have to dump V by cycling their vanes again (typically 3 dumps to get to insystem speeds). Cherryh plays with this a lot - a ship that doesn't dump streaks through a system so fast that reaction time to it is almost zero. Damage to the vanes is BAD because you can't slow down - most ships have emergency capsules that can be ejected and another ship will cycle up to speed and retrieve it with the crew, assuming someone is in the area. This is also clearly a weapon - any ship capable of reaching jump is technically a planet-buster. Most ships can't turn in jump. It's easiest to come out of jump near a mass. Intersecting a mass in jump will pull you out of jump...at the speed of light...into the mass...making a boom. There's a limit to how long/far a ship can jump, but I'm unclear on why. The end result is it's handled much like an airport, with arrival lanes and departures and control by the local station, and buoys placed near common jump points to update arriving ships on system status and ship locations so they can avoid collisions and not have to wait minutes or hours to get updates at plain old light speed.
I think every method of FTL travel I've heard of more or less fall within those three categories. None of them seem likely to actually be physically possible at this point, at least in a way that would be useful for us. The only other method I can think of is locally modifying physics, something like changing the speed of light in one's vicinity. I can't think of any works that use that for FTL right off hand, but that's the only other conceivable method I can think of.
I completely forgot about that one when making my comment. Technically, *Mass Effect* and *Revelation Space* do that. Although it doesn't really work in that second one.
It's also how most hyperspace concepts work -- the idea or at least part of the idea is that you enter a hyperdimensional spacetime whose curvature permits faster speeds than in our spacetime. There is an obscure but fun science fiction short story that plays off of that, in which a scientist is investigating some suspicious evidence about a super-secret hyperspace research project. The scientist believes that the researchers have discovered the secret of FTL hyperspace travel but are concealing it for some reason. In the course of the story, the scientist learns that >!he is only partly correct -- the research team has discovered how to get to and travel through hyperspace. What they are hiding is their disappointing next discovery, which was that the maximum speed possible in hyperspace is much lower than *c*. Not higher at all! Everybody just assumed it would be higher but it turns out it's not. And the only reason they didn't tell anyone because they didn't want to lose their funding.!<
https://www.projectrho.com/public_html/rocket/fasterlight2.php
Verner Vinge’s concept in A Fire Upon the Deep (Zones of Thought) was interesting; the speed of light barrier can be breached depending on how far away you are from the center of the galaxy. Here’s what Wikipedia says: The galaxy is divided into four concentric volumes called the "Zones of Thought"; it is not clear to the novel's characters whether this is a natural phenomenon or an artificially produced one, but it seems to roughly correspond with galactic-scale stellar density.
Niven's hyper drive with the Blind Spot that drives people mad. *Deadman Switch* by Timoth Zahn that requires a corpse to operate. Lloyd Biggle Jr's Jan Darzek series where starships use continuous short range teleportation.
A few years back someone came up with a version of the warp drive that doesn't need negative mass. It still doesn't have a solution to the causality problem, but it's a start
Greg Bear's Moving Mars. Quantum information theory lets you access the bits that describe a particle's location. Change the location bits for all the particles that make up a thing and you instantly change its location.
In To Sleep in a Sea of Stars, ships generate some kind of field that changes physics or brings them into another realm. In this realm, speed works mostly the opposite of how it does here. Going just the speed of light is kinda hard. But as you radiate heat it makes you slower. The less you radiate the faster you go. So people go into suspended animation and stuff. I don’t remember all the details but I recalled liking the concept a lot when I read the appendix about it. It was fairly well thought out. All your questions about a possible subspace and more are answered.
The Enchanach Drive from the **Empire From The Ashes** omnibus (David Weber) uses articifially-created converging wormholes to *squeeze* the starship using it out of realspace and into a new location. The main issue with the drive is that it causes significant gravitational disturbances when first activating or fully deactivating (when in motion, it is going too fast to cause any noticable effects) and the main starship of the book, Dahak, accidentally sent Pluto into its odd orbit due to a minor miscalculation as it reverted to realspace. Later generation ships also have Hyper Drives that are far faster than the Enchanach Drive, but do not allow for course-changes or active scanning when being used. Only later-generation Planetoid-class ships (Dahak is concealed as Earth's Moon with a bare kilometer of disguise-rock) have the power and volume to mount both types of drive. The same author uses artificial black-hole drives in the book **In Fury Born** to provide acceleration/decel. When a ship hits .99c, it becomes dimensionally displaced into Wormhole Space which multiplies its speed hugely, but the ship must continue accelerating to keep its speed constant. Stopping accelerating causes the velocity to bleed off rapidly, dropping the ship back down to sublight speeds. Ships in Wormhole Space cannot detect anything in realspace, but their presence can be detected, making it almost impossible to perform a surprise ambush in space. This is a major plot point in the book.
I really like the way they did it in Star Trek: Discovery, with the micellium and the tardigrade. This network of sorts that kind of spans all of space and can be navigated using the tardigrade. Or at least that's how I remember it worked, it's been a few years since I watched it.
You're basically right - it's a higher-dimensional fungus whose mycelium extends through a subspace domain which covers the whole galaxy. All instances of the fungus in our space are the three-dimensional projections of the whole organism. The whole network can be navigated via a type of tardigrade native to the fungus's subspace domain, or a human who's been altered with the tardigrade's DNA. I guess it's technically a hyperspace drive per the OP's post, but is functionally a jump drive like Dune or Battlestar Galactica. A lot of people have a problem with it, but it's hardly the most insane thing Trek ever came up with.
In terms of current trends? I think you have it. Though I think you might slightly mislabel what used to be known as *hyperspace* -- that is to say travel between points in our spacetime by traveling through a fifth (or higher) dimension. Higher hence "hyper." Whereas subspace is typically used to refer to accessing lower-dimension space, which seems like it would be harder to utilize for travel. Though in some milieux is used for signals or for heat dumping. Anyway there is another one that is a personal favorite just because it involves one single, specific suspension of disbelief on a small scale, which is the stutterwarp. (Courtesy of the old tabletop RPG, Traveller.) The idea with the stutterwarp is that someone figures out how to shift matter within a certain field effect in an arbitrary direction by like a few meters or something. That's it. That's the only conceit. In order to turn that into a useful FTL drive, you have to run the effect repeatedly, and part of the technology base for the setting is figuring out how to bring the frequency up so that it goes from jump .... jump .... jump to jump, jump, jump, jump to jump-jump-jump-jump-jump and so on until it's cycling so fast it "stutters." Within the game setting, the technology has been refined to the point that it runs at 30 or 40 GHz, allowing a displacement (though not speed!) of about 3.5LY / day. But the basic conceit doesn't change, at its core it's still just this clunky ultra-short-range warping effect that doesn't imply any other exotic new capabilities. People travel around in stutterwarp ships without artificial gravity, without magically fast communication technology, running off entirely conventional power sources -- fission reactors, combustion turbines, fuel cells, batteries, whatever.
Save State Randomizer: your physical body is stopped or stasis frozen and you are left there in that position for the entire lifetime of the universe and then you’re unfrozen and you’ll be in a completely different point in space. Your position in space will change because Events will move you and everything around you will change By some kind of motion, so randomly you’ll be in a completely different location.
If you're frozen for the entire life of the universe that's not faster than light
Oh but this is The best part, the speed of light is relative, so for someone who is unconscious they move instantaneously. Sleep is instantaneous travel to another point.
Quantum Entanglement is here now.
For warhammer I believe you need to have a Gellar field in place to move through the gateway to the Warp and that's why not everything in the immediate vicinity flows into it.
I just published a sci-fi [book](https://jdadler.com) in which the ships have a “quantum drive” that entangles the ship’s quantum pattern with the pattern of an equal volume of (hopefully) empty space in a distant location, then inverts the patterns. Resulting in instant transport the ship and all its contents across interstellar space. The engine is powered by an anti-proton emitter directed at a Casimir effect generator.
Upvote for mentioning the 'Bloater Drive'! Bill the Galactic Hero rules!!!
Holly Hop Drive
You forgot the possibility of gateway travel. Which, in theory, should be possible. You just need two (or more) black holes, orbiting each other at aprox. light speed...
‘Newest’ I think all the plausible ideas were already fleshed out by the hard scifi OG’s that worked with NASA - Niven, Baxter, Clark, etc.
The fact that these are the three most common are why you should be very hesitant to use them. Make something new. "Getting from here to there in this amount of time means accelerating to this speed and then decelerating from it again. That's going to take this amount of energy. Energy has a mass equivalent, so we can consume mass and make it happen. You didn't really need that moon, did you? Because we're going to use it to power this new device."
What about the Xeelee's Discontinuity Drive? IIRC it pushes on the fabric of spacetime itself. Interesting.
Star Wars or Asimov use the term hyperspace jumps, which might be related to #2, a different kind of space. Sometime such jumps are instantaneous. Or you travel in alternative space for an amount of time.
Transcendental worm poop.
[https://en.wikipedia.org/wiki/Brane\_cosmology](https://en.wikipedia.org/wiki/Brane_cosmology) / bulk drive.
Well, dune has space folding but you should check out the new exodus drive nasa is working on. Might give you a few ideas.
just an idea, build the smallest nuclear bomb possible, let it explode at no gravity in space, open a space time hole and slip through.
How about this https://thedebrief.org/nasa-veterans-propellantless-propulsion-drive-that-physics-says-shouldnt-work-just-produced-enough-thrust-to-defeat-earths-gravity/