"A question about wormholes" Topic

I am trying to come up with a manner of interstellar travel that is faster than allowed for by traditional hard science, but that doesn't violate causality for a game background.

I was considering a theoretical wormhole network where each stellar system contains one or more points where wormholes can be formed.

My thought is that there would be several points located at N-body Lagrange points within the system where wormholes can be formed by sending a relativistic particle beam along a line connecting two of these points within the system. Once the relativistic particle stream connects the two points a stable wormhole forms allowing one-directional travel through the wormhole in the same direction the particle stream is traveling. The wormhole remains open for as long as relativistic particles are connecting both wormhole points.

Also, there would be interstellar wormhole points located at the equilibrium point between the intra-system wormhole points. You would be able to open interstellar wormholes in the same way by sending a relativistic particle beam along a line connecting the interstellar wormhole points in two star systems.

Once the wormhole is established, you can almost instantaneously travel through the wormhole, but in only one direction.

If you wanted to travel back, you would have to shut down the original particle beam, wait for the wormhole to close, calculate a new firing solution for your relativistic particle beam from the destination back to the origin, wait for the particle beam to travel at relativistic speeds to connect the wormhole points in the opposite direction and then, once the new wormhole is established, you could travel back to your origin.

Would this violate causality?

You can travel nearly instantaneously in one direction, but to get back you would have to wait for a relativistic particle beam to travel back to the origin to activate the wormhole in the reverse direction.

Does this delay preserve causality?

I think the delay required to establish a wormhole back to your origin should prevent any time travel scenarios, but I could be wrong.

Even If you traveled through several already established wormholes that connect back to your original destination, you would be able to travel great distances nearly instantaneously, but you still shouldn't be able to travel backward in time. You would just be able to travel an enormous loop and be able to arrive back at your origin a few milliseconds later.

If this doesn't violate causality, it would result in neat wormhole network that would allow you colonize outwardly at initially relativistic speeds with following travel (i.e. supply) occurring nearly instantaneously, but in only one direction.

So, there would be an initially slow outward expansion as pathfinders travel at relativistic speeds to nearby stellar systems to map them out and calculate the wormhole points. However, once wormholes are established between systems you have near instantaneous one way travel.

This creates all sorts of interesting points of military significance.

Any thoughts you might have on this idea are welcome.

I think you are over thinking this.
Are you working on game rules?
Are you working on a sci-fi story?
Are you submitting a paper to Physical Reviews?

If the first, do what you want, and explain it all away with handwavium. Tell those who ask too many questions to get you a beer and shut up.

Sounds fine to me. Given the travel time is 'almost instantaneous', it should not be possible to travel backwards in time when going through the wormhole; you are only travelling between two points faster than a beam of light would if it takes the long way round through normal space. Therefore, causality wouldn't be violated.
Rather than relativistic particle beams, try a mechanism relying on quantum entaglement of pairs of photons – send one of the photons to the destination, detect it there, and the link between the photons will collapse instantly over any distance, allowing instantaneous information transfer between the points. (Such a system would work more like the transporters in Star Trek than a wormhole, but the overall effect would be the same).

OFM+1

The problem is that although locally the causality is not broken for the traveler, it is broken for any external observer. This will be the case with any solution you find to justify speeding above light if you want to be physically rigorous. The handwavium of course can override these effects, but not the known physics for now.

@acronim.

I don't think this is the case. The wormhole network is a closed system.

Any external observer would only "see" the traveler disappear in one place and reappear at another a few milliseconds later.

Of course, depending on how far they are from the traveller's origination and destination, they wouldn't "see" these events until long after they happen because of how long light takes to travel outside the wormhole.

They may even "see" the events occur out of order if they are closer to the travellers destination than origin, but this just an illusion and not a problem since the events don't actually occur out of order and the observer can figure out the correct order of events.

Furthermore, even if the observer sees the events out of order, there is no way for the observer to communicate what he sees to anyone else in a way that the message would arrive before the event actually happened, which is what would violate causality.

@OFM

Perhaps I am overthinking it.

I'm trying to create a board game with scenarios based upon the ramifications of wormhole travel between star systems. Therefore, I'm trying to create an at least internally consistent paradigm for how wormhole travel works.

One of the requirements I'd like to have for my internally consistent paradigm is that it doesn't violate causality (i.e. permit time travel).

One scenario I have in mind for the board game is that a colony ship has been sent out to a nearby star system at say .25 c. It's a long journey, say 75 years, and the crew is in stasis.

Let's say about 10 years after they leave there is some catastrophe at the colony ship's destination and it's no longer habitable.

Maybe 15 years after they leave much faster drives become available and a rescue can be attempted.

And maybe 20 years after they leave interstellar wormhole travel is established and a new habitable destination is discovered.

I'm trying to figure out what the technology advancements would look like that give rise to such a scenario. i.e. what should the colony ship's capabilities and mission profile look like, what should the rescue ship's capabilities and mission profile look like, what should the wormhole system's capabilities look like, and when should the advancements take place for the scenario to be feasible?

@noggin

I actually want pseudo fixed wormhole or jump points and long startup times to establish wormhole connections between star systems.

Exploration is costly and time consuming, but once the investment is made colonization is relatively easy.

I also don't want to be able to create wormholes anywhere you want. My system places them at pseudo fixed locations (they move around relative to the bodies in a star system, but their positions are calculable and the players can't manipulate their location).

@Daricles

Stephen Hawking himself tried to show by calculations that causality cannot be violated by a wormhole, and failed.

But if we are talking about a game, I think you can come up with the mechanics that suit you best.

The best thing would be for a TMP user from the future to come through one of those wormholes and explain to us.

Well, I'm not Hawking, but I don't see how the theoretical model I've proposed could violate causality.

Maybe it's not theoretically possible for it to work this way according to real science, but that's not what I'm asking.

I always liked Babylon 5's system, where important places had a Gate, which allowed access to Hyperspace, where ships could travel at much greater speeds to another gate.
Bigger or more advanced ships had their own Jump engines so could enter or exit Hyperspace fairly freely.

Daricles, you are master of technobabble. After reading just the first paragraph of your original post (most of it, anyway), it became clear to me that your system will work perfectly in your science fiction universe.

When do we get to see pictures of your spaceships and read your after action reports?

If you can find a copy of the old Metagaming game Warp War, I always thought it handled the idea of ships with different technology levels, some that could pass through the warp gates and some that were restricted to specific systems, was simple and logical. I may ,of course, be seeing the game through the fog of time, so keep that in mind.

Seriously, I think your original idea is fine. If a person leaves Earth and arrives at Alpha Centauri, he cannot possibly arrive before he left, according to your system. He can arrive before the light bouncing off his ship reaches Alpha Centauri, but that's got nothing to do with causality— time on Earth is already 4.5 years along, and the people on Alpha Centauri are just watching the equivalent of an old TV show, claiming to be "live," and he's saying, "Oo, look— this is the best part!"
He's outrun the messenger, but not the source of the message.

Think of it this way:
He enters the wormhole at 6:00:00:00PM today, Sunday, March 28, 2021. Through the wonder of wormhole travel, he arrives at Alpha Centauri (relative to Earth time) at 6:00:00:01PM the "same" day. He may beat a radio call saying he's coming by 4.5 years and some odd seconds, but so what? Even if he instantly turns around and goes back, he arrives at 6:00:00:02 to say he forgot his keys. So he never actually goes "back" in time at any point, even if the caller sees him return, and says "Never mind" and hangs up— after all, the call arrives 4.5 years later (Earth time), confusing anyone who answered, but never violating any causality.

Now, there's probably some stuff going along with the whole "faster clocks" thing, but for the purposes of your game scenarios, you can pretty much ignore it. Physicists don't pop up in gamer's houses waving warrants to arrest people for theoretically violating causality. Heck, most physicists are big fans of Star Trek, Star Wars, Battlestar Galactica, Flash Gordon, etc., etc., and don't really care if a basic premise of a show plays fast and loose with the speed of light— and they'll happily play your game without much argument, either.

I say this as someone who has written more than one space combat game, even going so far as to recalculate the Cosmological Constant to make vector travel and gravitational acceleration work in a hex-based game— I assure you, while it was fun to do, it was a complete waste of effort in the end.

(I'm not yet cured of that obsessiveness— I'm working on a children's science fiction novel, and I'm calculating actual sizes and spin rates for a Bernal sphere because some bizarre part of my brain says I have to get that "right." I really, really don't.

(I'm not yet cured of that obsessiveness— I'm working on a children's science fiction novel, and I'm calculating actual sizes and spin rates for a Bernal sphere because some bizarre part of my brain says I have to get that "right." I really, really don't.

Spincalc is your friend:

link

@Parzival

And what would an outside observer see, halfway and right next to the hole to make it simple? 0.5 seconds after leaving he would see it pass in front of him through the hole, 2.25 years later he would see it leave; in short, to the outside observer, it would have passed him before leaving. From the moment he has passed in front of him, as the traveler is faster than light, the observer would see two ships at the same time, one approaching and the other moving away, although it would be the same. It is in this sense that causality is broken for external observers.

As both a game designer and an SF Author, I'd say that perhaps you are going about this backwards. You start out with the result you want (either a set of game rules or a plot for a novel) and then work backwards to develop the FTL system that allows your result to work.

@ Acronim

I'm not really following your description. How can an observer be "halfway and right next to" a wormhole at the same time? "Halfway" to what? Alpha Centauri?
If the observer is halfway to Alpha Centauri, he sees the entry at either end 2.25 years after it happens, and the exit at either end 2.25 years after that happens. He sees NOTHING in the wormhole because there is no "next to" in spacetime which corresponds to the "midpoint location" of the wormhole— the wormhole itself doesn't exist with regard to spacetime in a physical, externally observable sense. It has one end and another end but nothing in the middle, as far as normal spacetime is concerned. There can be no light emerging from the wormhole itself to observe a ship's passage through it, regardless of how "long" that passage appears to take to the person inside or to someone observing from outside.

Let's say the "halfway" position is in physical spacetime between Earth and Alpha Centauri and the observer is positioned so as to somehow receive light from both wormhole openings. The person sees the ship enter the wormhole on Earth 2.25 years ago and emerge at Alpha Centauri 2.25 years and 1 micro second later. It then reverses, entering the AC end 2.25 years and 2 micro seconds ago, and emerges at Earth 2.25 years and 3 microseconds ago. But he never sees the passage of the ship, as that would be impossible— there's no passage to observe. Merely the departure and the arrival, at evenly spaced intervals.

If you don't want your rules to allow violating causality, simply don't allow it.
I will not charge you my usual playtesting fee. Donate it to your local no-kill animal shelter.

Simple explanation. One essential paradigm of physics is that "constants" are universally constant. For example "g" is anisotropic. It's a fundamental constant that is assumed to be constant everywhere in the universe. It has to be, or our equations couldn't be relied on!
So make time equivalent everywhere and is always moving in the same direction. If you leave Earth at time "T", you can arrive anywhere at "T + t". Never "T – t". Because Time is always universally moving forward.
Make your donation in the name of John the OFM. We don't need Hawking for this.
It's also how you make the trains run on time.

@Scott

That is basically what I am doing. I haven't posted my entire deliberative process here, just a question regarding a point in the process.

@acronim

In addition to what Parzival said, it does not even matter if the observer sees the traveler exit the wormhole before he sees him enter it because of where he is positioned in normal space.

That does not violate causality. The events do not occur out of sequence just because an observer sees them out of order.

A sophisticated observer will see the events occur out of order and will conclude the traveler somehow traveled faster than light. He can even then calculate the correct sequence of events by figuring how long the light took to travel to the observer's location from each event.

Causality would only be broken if the observer could somehow send a message to one of the involved locations that would arrive before the event at that location takes place.

My theoretical system does not allow that possibility as far as I can see.

Other than having to travel to your destination through normal space to setup the other end of the wormhole, instead finding and traveling through preexisting wormholes, you've just invented the board game Starfire.

Here is my in Universe wormhole plot device
link