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Which Method of FTL Travel is the Most Believable?


JMBuilder

Hypothetical Methods of FTL Travel  

22 members have voted

  1. 1. Which method of FTL travel is most believable to you?

    • Warp Drive - Bending a confined region of space around a spacecraft.
      10
    • Hyperspace Jump - Interpreting and mapping the fourth spatial dimension to instantly jump from one point to another.
      2
    • Brute Force - Somehow conventionally thrust a spacecraft beyond the speed of light.
      0
    • Tachyon Sailing - Detecting streams of faster-than-light particles and hitching a ride on them.
      0
    • Negative Velocity - Finding some bizarre way of travelling one way and arriving somewhere in the opposite direction.
      0
    • Black Hole - Dive into a singularity and hope you don't end up scattered across another universe.
      1
    • Intertwined Universe - Entering some kind of parallel and elongated universe and exiting at the desired location (for example, "Slipspace" in the Halo series).
      2
    • Wormholes - Narrow "bridges" of 3D space through 4D space.
      7


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Negative velocity doesnt make sence. Do you mean Imaginary velocity? it's a bit complicated to explain, but adding a Sqrroot(-1) component to your velocity lets you sidestep the worst of the time/mass dialation related to acceleration to lightspeed, letting you re-merge with "normal" space on the other side of the light barrier.

It was in novels I read by a physisist, Cathrine Asaro.

Edited by Rakaydos
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4 minutes ago, Rakaydos said:

Negative velocity doesnt make sence. Do you mean Imaginary velocity? it's a bit complicated to explain, but adding a Sqrroot(-1) component to your velocity lets you sidestep the worst of the time/mass dialation related to acceleration to lightspeed, letting you re-merge with "normal" space on the other side of the light barrier.

It was in novels I read by a physisist, Cathrine Asaro.

It's just a brain dump for another option. I added it just because it sounds paradoxical.

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I'm also something of a fan of the FTL in Old Man;'s War.

Basically, they jump into a parralel dimention formed by the decay of a quantum superposition somewhere in the nearly infinite universe. Since it's easier to reach universes closer to our own, that one Schrodinger's atom is the only difference between the universes. But you arrive in the dimension in a different place than alternate-you (who, odds are, do not contain that Schrodinger atom) left the dimension, giving you EFFECTIVE FTL.

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Alcubierre/warp drive seems at least plausible if you had obscene amounts of energy (say, a large antimatter engine, like in Star Trek). I don't see anything obvious in relativity that says it absolutely can't happen. You might end up with some weird time jumps happening, though, and it's still dubious whether we can get/manufacture enough antimatter and store it adequately.

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To be honest, none of them are really plausible yet until we find a way to make negative mass, assuming that exists. It may not be possible, but we don't really know yet. Hopefully it is!

There's a whole cosmological model focused on trying to make sure it's possible... but sadly, there's little evidence for it (it fits the data just as well as other models) and may suffer from a bit of "ad hominem" as the guy who made it is... a bit crazy...

 

But hey, I'm still hopeful. One day...

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I honestly think that hyperspace jumps would be the best and most plausible method (assuming that a fourth spatial dimension would still be bound by our one time dimension). No time dilation. No fear of collision. Just punch in the 4D calculations and bam.

Problem is, we'd need some method of mapping 4D space, as stated in the poll. I've always envisioned some kind of "hypermatter" acting as a foot in the door to hyperspace. We'd just need a way to contain it.

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No wormholes, huh? Or even Krasnikov tubes? At least those are valid solutions of GR...

Of course, any system that lets you get FTL (even just apparent FTL) runs the risk of becoming a time machine. This means that you might only be able to use it in one direction. For warp drives, you're causally disconnected from the universe, and can't turn it off from inside. This means that you need an external station to turn it off. But if you have near lightspeed travel, you could go to the target star near lightspeed and then warp back to Earth, and hopefully get stopped by a station that can deactivate the warp bubble...

Honestly the most believable method would be wormholes. Orions Arm has a well constructed example, and Luke Campbell's Vergeworlds wormholes are actually pretty interesting. Of course there isn't any FTL travel, but causality could still be violated. Unless there are quantum effects preventing that...

Whatever you think, if you're writing a story make sure to take into account the consequences. In Orions Arm wormholes are massive objects that must be quite far away from the planets in a solar system, limiting their effects. Meanwhile Vergeworlds has microscopic wormholes of similar mass to subatomic particles, and thus all sorts of things such as communication, energy generation, industry, and more are affected by this. Space travel may not even be necessary.

Edited by Bill Phil
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39 minutes ago, Bill Phil said:

No wormholes, huh? Or even Krasnikov tubes? At least those are valid solutions of GR...

Of course, any system that lets you get FTL (even just apparent FTL) runs the risk of becoming a time machine. This means that you might only be able to use it in one direction. For warp drives, you're causally disconnected from the universe, and can't turn it off from inside. This means that you need an external station to turn it off. But if you have near lightspeed travel, you could go to the target star near lightspeed and then warp back to Earth, and hopefully get stopped by a station that can deactivate the warp bubble...

Honestly the most believable method would be wormholes. Orions Arm has a well constructed example, and Luke Campbell's Vergeworlds wormholes are actually pretty interesting. Of course there isn't any FTL travel, but causality could still be violated. Unless there are quantum effects preventing that...

Whatever you think, if you're writing a story make sure to take into account the consequences. In Orions Arm wormholes are massive objects that must be quite far away from the planets in a solar system, limiting their effects. Meanwhile Vergeworlds has microscopic wormholes of similar mass to subatomic particles, and thus all sorts of things such as communication, energy generation, industry, and more are affected by this. Space travel may not even be necessary.

I sort of lumped wormholes in with "hyperspace jumping." IMO, Interstellar got the idea of a wormhole a bit wrong. If it's really just overlapping space with a hole through it, the wormhole would have just immediately wrapped around them instead of becoming a thundering tunnel of trippiness.

EDIT: I added it as an option.

Edited by JMBuilder
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57 minutes ago, JMBuilder said:

I sort of lumped wormholes in with "hyperspace jumping." IMO, Interstellar got the idea of a wormhole a bit wrong. If it's really just overlapping space with a hole through it, the wormhole would have just immediately wrapped around them instead of becoming a thundering tunnel of trippiness.

EDIT: I added it as an option.

There are multiple types of wormholes. Some have an actual throat, a region of flat spacetime between the two ends, that must be traversed.

Interstellar was probably going for a 2001: A Space Odyssey vibe...

Also, wormholes may not exist in nature. As such, they may need to be artificial. They're also more accurately described as a spacetime distortion that connects two points in spacetime (and they don't have to be at the same point in time, either, thus why they could create a time machine).

Edited by Bill Phil
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There are some repetitions there. Hyperspace and Intertwined are essentially the same idea of having a separate space that provides a shortcut. Details of the shortcut hardly make a difference, really. Then you have wormholes and back holes. These, likewise, are variations on the same principle. And while we're at it, Warp Drive is closely related. The limitations on all 3 are related to some conjectures about CTCs. Finally, tachyon sailing would be a type of brute-force, since you're still trying to punch the light barrier.

That said, the only thing we have any sort of math on is Wormholes and Warp. So they look most plausible right now.

P.S. Yes, causality goes out of the window with any of these.

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5 minutes ago, Nutt007 said:

Which one keeps both Relativity and Causality intact?

 

Pick two:

  • Relativity
  • Causality
  • FTL

It seems like an instant hyperspace jump (again, assuming that the 4th spatial dimension is bound by one dimension of time) wouldn't butcher causality. But, of course, I don't fully understand this stuff... The extent of my knowledge is coming from Rudy Rucker's The Fourth Dimension and various obscure sources. :P

 

5 minutes ago, K^2 said:

There are some repetitions there. Hyperspace and Intertwined are essentially the same idea of having a separate space that provides a shortcut. Details of the shortcut hardly make a difference, really. Then you have wormholes and back holes. These, likewise, are variations on the same principle. And while we're at it, Warp Drive is closely related. The limitations on all 3 are related to some conjectures about CTCs. Finally, tachyon sailing would be a type of brute-force, since you're still trying to punch the light barrier.

That said, the only thing we have any sort of math on is Wormholes and Warp. So they look most plausible right now.

P.S. Yes, causality goes out of the window with any of these.

Yes, they are variations of the same principle, yet distinct enough to separate.

A hyperspace jump is an instant jump through 4D space via two parts of our 3D space "overlapping" through it, warp drive is bending 3D space via 4D space, and an "intertwined universe" is an entirely separate 3D space from our own, accessed via 4D space. A black hole is obviously a point of immense mass theoretically creating a wormhole, but a wormhole wouldn't necessarily be the result of a black hole.

Tachyons are supposedly already travelling faster than light while brute force thrust uses normal matter and energy, so one method is "grabbing on" while the other is "pushing."

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15 minutes ago, JMBuilder said:

Tachyons are supposedly already travelling faster than light while brute force thrust uses normal matter and energy, so one method is "grabbing on" while the other is "pushing."

The effect on the ship is the same. Something continues to apply force to it as its punching through the limit. Depending on some details of the physics of vacuum, it's not strictly impossible, since we do see this work in very limited sense in fluids. See Cherenkov Radiation. But there is no indication that true vacuum allows for it, and any means of force mediation would have to survive infinite stress. So whether you're trying to build a rocket that does it, or use sails to capture something that's already moving FTL (all kinds of problematic in the first place, by the way,) it's absolutely not clear how to have your mountings survive the process. E.g., if your sail is made up of normal matter, yet somehow interacts with tachyons, the net effect ought to be your sale getting evaporated away. :/

All FTL ideas require us to stretch the known a little bit to admit the what-ifs, but you're definitely stretching it a lot more when you propose that there are other dimensions or that there are particles/materials that can survive brute-force approach (if the vacuum even supports it). So we're still looking at ways of working within General Relativity as the most plausible ones. And that's warp and wormholes.

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I've always been a bit confused as to why wormholes need to be constrained to the extent that they usually are. If the issue is that you might get there before your light/cause does, can't the light come through the hole too? My interpretation is that wormholes change space itself so that the entry and exit points are at the same place, which doesn't sound problematic. At least not in the relativistic sense. The only reason you can appear to move faster than light is because the hole wasn't always there, so the light missed it.

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11 minutes ago, 0111narwhalz said:

I've always been a bit confused as to why wormholes need to be constrained to the extent that they usually are. If the issue is that you might get there before your light/cause does, can't the light come through the hole too? My interpretation is that wormholes change space itself so that the entry and exit points are at the same place, which doesn't sound problematic. At least not in the relativistic sense. The only reason you can appear to move faster than light is because the hole wasn't always there, so the light missed it.

Wormholes are only allowed to connect events that aren’t in each other’s light cones, at least if you don’t want to violate causality, afaik.

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There's which is more plausible (tough, none really are), and there is which breaks the least other technology. For the latter requirement, I think that a jump drive makes the most sense. Other than that, I have nothing, they all break reality, but the others seem to have more constant interaction with the regular universe around them. I think jump makes the best storytelling cheat as well (100% normal physics, except hyperspace jump, which can then be arbitrarily limited however you like with handwaving).

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1 hour ago, JMBuilder said:

It seems like an instant hyperspace jump (again, assuming that the 4th spatial dimension is bound by one dimension of time) wouldn't butcher causality. But, of course, I don't fully understand this stuff... The extent of my knowledge is coming from Rudy Rucker's The Fourth Dimension and various obscure sources. :P

You're assuming that there's a universally meaningful "now" point in time to which you could jump at your spatial destination. The problem comes when you start combining your hyperspace jumps with relativistic speeds in normal space.

If your ship passes near my ship going east at 0.9c, and we both perform hyperspace jumps one light year eastwards, we'll emerge at different points in time, because our "now" times at that point in space are different. That's how jump drives become time machines. I believe Stephen Baxter's Exultant uses this to travel back in time.

Edited by HebaruSan
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1 hour ago, 0111narwhalz said:

I've always been a bit confused as to why wormholes need to be constrained to the extent that they usually are. If the issue is that you might get there before your light/cause does, can't the light come through the hole too? My interpretation is that wormholes change space itself so that the entry and exit points are at the same place, which doesn't sound problematic. At least not in the relativistic sense. The only reason you can appear to move faster than light is because the hole wasn't always there, so the light missed it.

The issue is that your wormhole ends can be in the same space at different times. So you can go in one end of the wormhole, come out the other side, earlier, then GO BACK INTO THE FIRST END (again, before you went in the first time) to go further back in time.

1 hour ago, K^2 said:

. So we're still looking at ways of working within General Relativity as the most plausible ones. And that's warp and wormholes.

Hey, there's still i-vector thrust to sidestep lightspeed...

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Shifting of the observer's projection across the multiverse landscape or manipulations with wavefunction.

Maybe some discoveries of hypertunnel physics after reaching the closest stars by non-relativistic ships and founding an interstellar physical lab.

P.S.
I still don't understand why the 4th spatial dimesion is considered as a way to hyperjump. The 3d coordinates anyway stay the same.

P.P.S.

2 hours ago, Nutt007 said:

Which one keeps both Relativity and Causality intact?

Some models of multiverse.
If everything possible is already contained and by definition nothing happens, then the cause and the effect depend on the angle under which you look at the multiverse landscape.

Edited by kerbiloid
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