Sci-Fi insterstellar travel idea...

[FireNexus]

I'm kicking around an idea for sci-fi interstellar travel, and thought I'd see what people thought of it. I'd refer to this as "pseudo-FTL" travel, because the person within the craft deploying this method of travel would feel as if there was an instantaneous transition from point A to point B, but the travel would actually be light-speed travel.

The idea would essentially be a wormhole that you can open to connect two regions of space. It would open instantaneneously on both sides, and be affected by gravity such that it could be made stable relative to large stellar bodies near it, but no information or matter would travel through it faster than light speed. If I open a bridge connecting earth and alpha centauri, it would appear as a non-gravitational black hole for the period of time it would ordinarily require for light or matter to pass through it. Once you started receiving information, you would receive said information exactly 4.37 years after the bridge was opened, exactly as long as it would take light to travel there. So if you send matter through it, it would come out on the other side in a subjective instant, but 4.37 years would have passed for everyone and everything else.

It would contain an advantage over traditional interstellar travel only in that there would be no subjective passage of time for the traveler, and the ship would not have to carry the large quantity of fuel required to speed up and slow down, but it should still leave relativity intact.

What do you guys think of this as a travel method in fiction? Needlessly complex, so-so, or really cool?

[Zixinus]

Depends how you are going to use its possibilities.

I also recall Freefall using the opposite of this idea, more-or-less: for the universe, the travel is instantaneous more-or-less, however for the crew it is still felt for several years. They put all the organic members in deep-freeze sleep.

[RedImperator]

I'm kicking around an idea for sci-fi interstellar travel, and thought I'd see what people thought of it. I'd refer to this as "pseudo-FTL" travel, because the person within the craft deploying this method of travel would feel as if there was an instantaneous transition from point A to point B, but the travel would actually be light-speed travel.

The idea would essentially be a wormhole that you can open to connect two regions of space. It would open instantaneneously on both sides, and be affected by gravity such that it could be made stable relative to large stellar bodies near it, but no information or matter would travel through it faster than light speed. If I open a bridge connecting earth and alpha centauri, it would appear as a non-gravitational black hole for the period of time it would ordinarily require for light or matter to pass through it. Once you started receiving information, you would receive said information exactly 4.37 years after the bridge was opened, exactly as long as it would take light to travel there. So if you send matter through it, it would come out on the other side in a subjective instant, but 4.37 years would have passed for everyone and everything else.

It would contain an advantage over traditional interstellar travel only in that there would be no subjective passage of time for the traveler, and the ship would not have to carry the large quantity of fuel required to speed up and slow down, but it should still leave relativity intact.

What do you guys think of this as a travel method in fiction? Needlessly complex, so-so, or really cool?

This is exactly the method I chose in the rewrite of The Humanist Inheritance, after Discombobulated/Metatwaddle pointed out that my previous idea violated conservation of energy.

[Hawkwings]

If it opens "instantaneously" at both ends, then some information is being transmitted faster than light.

[FireNexus]

I was actually thinking that, but I reasoned that the information being transmitted is so miniscule as to not really violate relativity, since it cannot in any way violate causality. The only information transmitted is "aperture at this point". At the receiving end there is no way of knowing where the aperture leads to without spending the time finding out through normal relative means.

[Havok]

FireNexus
Other than saving on supplies and fuel...what is the point?
It wouldn't seem to have any military advantage, since if you are trying to get some where, the time for everyone outside the traveling ship would have passed as normal, and you (reinforcements or whatever) still show up 4 years later even though no time has passed for you.

I guess for exploration it would be nice, but then you limit yourself to how far you can go... Too far and the world you come back to will be totally different.

This is Science-Fiction. Not everything needs to make perfect sense or adhere to every law of physics, especially if the story is good. If you need to travel FTL in your story, just do it. Unless your story revolves around the "FTL Travel is new" theme or whatever.

[Admiral Valdemar]

The energy for producing something like this would likely be just as, if not worse, than travelling at high relativistic velocities via a Bussard derivative or something more exotic. I don't see how it could be easy or safe, given the nature of playing with space-time compared to simply traversing space as normal.

[GrandMasterTerwynn]

I was actually thinking that, but I reasoned that the information being transmitted is so miniscule as to not really violate relativity, since it cannot in any way violate causality. The only information transmitted is "aperture at this point". At the receiving end there is no way of knowing where the aperture leads to without spending the time finding out through normal relative means.

From a naive read of your idea, if you could arbitrarily spawn and destroy apertures, you'd have a nifty means of FTL communication simply by spawning/destroying bridges at intervals determined by some previously agreed-upon system . . . i.e. a sort of interstellar Morse Code. You'd never have to actually send anything over.

[Admiral Valdemar]

Exactly. Anything appearing anywhere faster than light is FTL and a violation.

[Darth Smiley]

The obvious solution is to not have the exit portal appear until however long needed for lightspeed lag, and maybe a little slower (ie - the equivalent of .95 c or something like that).

[Batman]

The obvious solution is not to bother, actually. As it takes information just as long to travel through the wormhole as it does traveling through realspace the concept is already useless for communications and as AV pointed out, the energy requirements of opening the wormhole in the first place are bound to rival if not exceed those of getting a starship across the distance the conventional way. About the only advantage that system has is the travelers not aging en voyage, and you can always use cryosleep for that.

[Jawawithagun]

The energy for producing something like this would likely be just as, if not worse, than travelling at high relativistic velocities via a Bussard derivative or something more exotic. I don't see how it could be easy or safe, given the nature of playing with space-time compared to simply traversing space as normal.

But once it is set up you can send whatever amount of ships through at minimal costs. There was no limitation on how often it can be used once it is set up.

[Keevan_Colton]

You could go with something similar to the idea used by Iain Banks in the Algebraist and also in EVE Online for the establishment of the network (though they have instant travel once they're in place): Both wormhole ends are created together and then moved into place by specialist ships. This means that the first time to a place would be a STL journey with the lightspeed option coming on line once the inital explorers have visited a place.

It gets rather more complicated than the good old cryosleep, but it can be done successfully.

[Junghalli]

The obvious solution is not to bother, actually. As it takes information just as long to travel through the wormhole as it does traveling through realspace the concept is already useless for communications and as AV pointed out, the energy requirements of opening the wormhole in the first place are bound to rival if not exceed those of getting a starship across the distance the conventional way.

On the other hand, assuming the apparatus is external to the ship, it lets you use spacecraft with much lower fuel fractions. For a ship getting up to .9 c you're basically talking about a flying fuel tank with a very tiny engine and payload attached. With this system that isn't true anymore; you can devote much more of the ship's mass to payload. There are major advantages to have a stationary power plant and portal apparatus as opposed to having to fit an equivalent rocket onto the ship itself: the former can be as big as your structural engineering will allow, the latter generally adds dozens or hundreds of kg of penalty mass for every kg of mechanism at the speeds we're talking about.

This is doubly true if you can use the same portal for an unlimited number of ships instead of just one.

Offhand, as a nonexpert, it seems to me that if your big worry is casualty protection some variant of the Alcubierre warp drive may be the best idea, since the ship inside the warp bubble experiences no relativistic effects, as opposed to a wormhole or Krasnikov tube, where it may if the ship is fast enough.

[Batman]

The obvious solution is not to bother, actually. As it takes information just as long to travel through the wormhole as it does traveling through realspace the concept is already useless for communications and as AV pointed out, the energy requirements of opening the wormhole in the first place are bound to rival if not exceed those of getting a starship across the distance the conventional way.

On the other hand, assuming the apparatus is external to the ship, it lets you use spacecraft with much lower fuel fractions

Assuming the wormhole is PERMANENT, of course.

[Gullible Jones]

This thing goes all the way back to Joe Haldeman - in The Forever War and Forever Free, he had "wormholes" that acted exactly like this.

[Lord of the Abyss]

The obvious solution is not to bother, actually. As it takes information just as long to travel through the wormhole as it does traveling through realspace the concept is already useless for communications and as AV pointed out, the energy requirements of opening the wormhole in the first place are bound to rival if not exceed those of getting a starship across the distance the conventional way. About the only advantage that system has is the travelers not aging en voyage, and you can always use cryosleep for that.

How about the fact that you can't push a starship to lightspeed, so this is certainly faster ?

Also; one argument against interstellar travel being practical is that at near-c speeds, a starship is too likely to hit some interstellar debris and be destroyed. This gets around that as well; you send an unmanned wormhole generator/carrier ( the latter if you need to make both ends and drag them apart ) to the destination, or several. If you send five, and only one or two make it, so what ? It's just hardware. Then you use the wormhole for people, for whom a 1 in 5 chance of survival * would be unacceptable.


* numbers pulled out of thin air as an example

[FireNexus]

It wasn't actually to make it work, but more what I thought would be an interesting mechanic to insert into a science fiction story as part of the background.

As far as the morse code idea, I feel like an idiot for not thinking of it. The energy situation I thought of, but figured I would magic some way around it. Thanks for the input.

[Illuminatus Primus]

Exactly. Anything appearing anywhere faster than light is FTL and a violation.

People forget "on-off" is information.

[SirNitram]

If you're set on this idea, pick up Larry Niven's short stories, particularly his Teleport Booth ones. They utilize it for FTL; the teleported ship experiences no time(It's existing as a wave/particle carrier, not a physical object during transit), but the universe does. Of course, you still have the whole conservation of energy problem(The first extrasolar teleport needs to be rapid-bounced from Pluto down to Mercury, as that's the only 'ship-booth' capable of handling large drops in potential energy).

[Admiral Valdemar]

People forget "on-off" is information.

Which is funny, because they seem to like picking up on the Ansible or lighthouse fallacy where you move a light beam at FTL by waving it, in order to convey information.

[Luzifer's right hand]

In the "Engines of Light" trilogy the ships travel at lightspeed as photons.
People using such a drive experience no time and with good enough control short jumps inside objects which have no entrance big enough for the vessels are possible.
MacLeod of course handwaves all energy related things IIRC, it has beens some time since I read the books.

I like the idea of a light-speed drive myself, not because of realism because I frankly don't give a shit about that, but because it's kinda cool.

[Axiomatic]

Call it an ETL drive, then?

[Surlethe]

This is exactly the method I chose in the rewrite of The Humanist Inheritance, after Discombobulated/Metatwaddle pointed out that my previous idea violated conservation of energy.

I've been meaning to tell you about that. Apparently, you can use this new method to violate causality or go FTL: take the new end that opens a light-year away a year in the future and tow it near c on a closed loop a light-year long; you're effectively bringing it back a year. Do it again, and you're creating a time bridge.

[Oskuro]

A doubt about the idea:

So, say you open a wormhole to a system, say, 4 LY away, and then traverse it. To you, the travel is instantaneous, but to the rest of the universe it isn't.... Wich means that the wormhole stays open for the whole 4 years, right?

If the wormholes are permanent, then ok, but if they are supposedly generated by the outgoing ship, its a bit weird.

Maybe a better option would be for the outgoing ship to start the wormhole, and then "ride" it to the destination, with the exit hole "reaching" the target a few seconds before the ship arrives, and the "tunnel" collapsing behind the ship (or even due to the ship's wake).

Of course, feasability considerations aside, all this does is "freeze" the ship for the duration, and kind of make it "out of phase" with the rest of the universe. (Why do I feel uneasy using the word "phase"?)

It makes me think of the Trade Lanes in the Freelancer game, wich accelerated you and made you intangible to asteroids or other ships, although they didn't make the travel instantaneous for the player (for obvious reasons)