How would a Heim- theory drive actually behave?

[Eleventh Century Remnant]

I'm kicking around a few ideas for semi- original fiction (as original as fiction ever gets, anyway) and as far as coming even remotely close to a space opera drive system goes, something based on Heim- Droscher theory might well be it. Problem is, past 'big power thing, stick on back of ship, go vroom' I'm really not sure I understand it.

The reason this is here rather than Science Logic and Morality is that however little I grasp of the fundamentals, I'm damn sure I don't understand the mathematics and I don't want to be equated to death. Enough comprehension of the implications to write science fiction about is all I'm after.

As far as I comprehend it at all, it is essentially a completely sideways way of looking at the universe, in which all known forms of matter and energy are patterns formed by knots in multidimensional spacetime. It could be a unification theory, if some of the predictions work out. And no, I don't understand the full implications of what I've just typed, that's what I want to ask about.

It's a big theory with a lot of implications; for one, it seems to predict the inflationary force- and if it can be generated, then we have an FTL drive. Damn' if I know how, though.

Electrogravity is one of the more common implications, and there has actually been lab work done with mixed results- there's sublight, but at what power requirement and efficiency?

Are there weapon implications apart from the obvious, missiles and super-railgun mass accelerators? Use an inflationary effect to dilate an enemy ship to death, transmute some of the target's mass to antimatter? defensive implications, and again at what cost in energy?
The more I think about it, the wierder it gets, and I know I haven't been perfectly coherent. help?

[GrandMasterTerwynn]

I'm kicking around a few ideas for semi- original fiction (as original as fiction ever gets, anyway) and as far as coming even remotely close to a space opera drive system goes, something based on Heim- Droscher theory might well be it. Problem is, past 'big power thing, stick on back of ship, go vroom' I'm really not sure I understand it.

As FTL drives are almost purely in the realm of fantasy, the answer to your question is "However it needs to behave within the framework of your desired story."

Slightly more serious answer.

To build a Heim-Droscher drive, you need a superconducting coil with an enormous current souce, and a swiftly rotating superconducting ring. Throw enough current at the problem, and spin the ring fast enough, and (so says the theory,) the entire contraption ought to shuffle off into hyperspace, and travel at ~50c until you shut it down. The upshot being that the superconducting materials capable of sustaining the sorts of current densities required are well into the realm of unobtanium. Slightly less-fantastic current densities are needed to produce antigravity.

[Eleventh Century Remnant]

Ah. right...thanks, that sort of explanation is exactly what I was looking for.

The motherlode site, heim-theory.org, seems to be only for the serious and dedicated, effectively closed to amateurs, so I've been rooting round other, mostly popular science, references.

I think I can do something with that. Cheers.

[Formless]

You know, I was interested in this as well. I already knew the things you would need to create the drive, and had an idea of how fast it could go (I'm guessing the 80 days for eleven light years number is factoring in acceleration/deceleration time with a brief excursion into hyperspace in between), but I'm interested in what side effects you might see when it is turned on? For example, I am under the impression that it circumvents the time travel issue of FTL somehow, but I'm unclear how.

[kinnison]

There is a type of material - so far only described in fiction - that might be able to sustain the immense current densities (and even more immense forces) involved in Heim-type engines and also might give the material strength required to make a macroscale object such as a ringworld. Unfortunately, as I know a lot of people here don't like the site or the setting much, the idea is found on Orion's Arm.

The idea is magmatter - a theoretical construct in which magnetic monopoles are substituted for the elementary particles of real matter. This stuff, because monopoles are so much more massive than any other particles, turns out to be immensely dense, immensely strong and probably capable of sustaining the required currents.

I have no idea whether this makes sense or not - my physics is EXTREMELY rusty - and I have even less idea, if possible, how this stuff might be made. Which is OK, because the concept also involves transapient superintelligences making it.

[GrandMasterTerwynn]

There is a type of material - so far only described in fiction - that might be able to sustain the immense current densities (and even more immense forces) involved in Heim-type engines and also might give the material strength required to make a macroscale object such as a ringworld. Unfortunately, as I know a lot of people here don't like the site or the setting much, the idea is found on Orion's Arm.

The idea is magmatter - a theoretical construct in which magnetic monopoles are substituted for the elementary particles of real matter. This stuff, because monopoles are so much more massive than any other particles, turns out to be immensely dense, immensely strong and probably capable of sustaining the required currents.

I have no idea whether this makes sense or not - my physics is EXTREMELY rusty - and I have even less idea, if possible, how this stuff might be made. Which is OK, because the concept also involves transapient superintelligences making it.

Until we have solid evidence for the existence of magnetic monopoles (which we decidedly do not,) it's pure handwavium.

[Ryan Thunder]

Until we have solid evidence for the existence of magnetic monopoles (which we decidedly do not,) it's pure handwavium.

There isn't even a theoretical possibility of it, though, is there? My understanding was that magnetism was caused by movement of charge, which, in the case of something like a bar magnet, is the result of electrons orbiting doing--whatever you call what they do--around atoms.

But the nature of this is such that it creates poles. So the issue is that it's like trying to have an up without a down...

[Eleventh Century Remnant]

Also, do magnetic monopoles have anything at all to do with- are they even possible under- Heim theory?

I know the theory is said to be able to derive most of the standard model's particle zoo but not all, predicts some things- like a neutral electron- that there is no evidence for currently, and is mutually incompatible with supersymmetry. Monopoles, I don't know where they fit in.

I have to say that from what little I know about Orion's Arm, I hope Ted Sturgeon was right. In addition to the famous "90% of everything is crud" statement, he's also quoted as saying "Science fiction writers don't try to predict the future. They usually try to prevent it." If that was the driving idea behind Orion's Arm- to prevent anything like that ever happening- it would make so very much more sense to me.

Anyway, the first thought that came to my mind when thinking of a Heim drive coil was 'fusion reactor'. Use a plasma as the spinning coil, obviates all the mechanical problems. Apart from those associated with a fusion reactor anyway. This is a no- math suggestion so it may be complete bullshit, but I think it just might be a shade more practical than transapient superintelligences doing bad god impressions- [deep booming voice]and on the pi-th day, it created handwavium[/deep booming voice].

The bit that disappoints me as a writer- and fascinates me as a potential citizen of the galaxy, well, ancestor of said citizenry- is that there's no separation between sublight and translight drive systems. Do one and you can do the other, in principle. With the intervening grillions of man hours and dodectzillions of currency to actually make it work, of course.

Is that eighty days for eleven light years estimate variable? Greater current density, more speed- or is it that this is how fast you can go? Chase scenes are going to be a bit predictable- and yes, I don't get the time travel aspect either.

[GrandMasterTerwynn]

Anyway, the first thought that came to my mind when thinking of a Heim drive coil was 'fusion reactor'. Use a plasma as the spinning coil, obviates all the mechanical problems. Apart from those associated with a fusion reactor anyway. This is a no- math suggestion so it may be complete bullshit, but I think it just might be a shade more practical than transapient superintelligences doing bad god impressions- [deep booming voice]and on the pi-th day, it created handwavium[/deep booming voice].

I think you're going to need a fantastically dense plasma (since you have to move a lot of electrons to achieve the stupendously high current densities required) only achievable with some freaky control over the electromagnetic force, or at least a hundred Jupiter-masses of, well, mass. This fantastically dense plasma will also be fantastically hot, and will need to be contained. Which introduces the mechanical problem of containing it. The container will also have to not attenuate the electromagnetic field between the coil and the ring. With aforementioned freaky EM manipulation, you could conceivably put all of this outside your ship, and also use the same technology to shield you from attack.

The bit that disappoints me as a writer- and fascinates me as a potential citizen of the galaxy, well, ancestor of said citizenry- is that there's no separation between sublight and translight drive systems. Do one and you can do the other, in principle. With the intervening grillions of man hours and dodectzillions of currency to actually make it work, of course.

Is that eighty days for eleven light years estimate variable? Greater current density, more speed- or is it that this is how fast you can go? Chase scenes are going to be a bit predictable- and yes, I don't get the time travel aspect either.

I'm not entirely sure about the max velocity, but I'm lead to believe that it is a direct result of the properties of the hyperspace the HD contraption would end up in. And the time travel aspect is simple relativity. Faster than light travel will invariably end up being time-travel in some frame of reference. Say you take a ship and you fly to Epsilon Eridani. You arrive eighty days later (from your frame of reference.) However, observers at Epsilon Eridani will not witness your departure from Sol for another ten years (the the information that describes your departure, i.e. photons and gravity waves, travels at the speed of light.) From their frame of reference, you've traveled ten years back in time, successfully sodomizing causality (your arrival at Epsilon Eridani from Sol magically occurred before your departure from Sol to Epsilon Eridani.) Sci-fi writers, however, handwave this little problem away all the time.

[Ryan Thunder]

Faster than light travel will invariably end up being time-travel in some frame of reference. Say you take a ship and you fly to Epsilon Eridani. You arrive eighty days later (from your frame of reference.) However, observers at Epsilon Eridani will not witness your departure from Sol for another ten years (the the information that describes your departure, i.e. photons and gravity waves, travels at the speed of light.) From their frame of reference, you've traveled ten years back in time, successfully sodomizing causality (your arrival at Epsilon Eridani from Sol magically occurred before your departure from Sol to Epsilon Eridani.) Sci-fi writers, however, handwave this little problem away all the time.

No. You merely outran your own light. How does that imply time travel?

[Stark]

Oh jesus, he doesn't understand relativity.

PS Ryan, if anything even information appears from some frame of reference to have arrived before it left, that's time travel.

[Eleventh Century Remnant]

Heim was writing after and with full knowledge of Einstein; I don't understand how he expected to be able to violate causality, unless it has to do with the inflationary antigravitic field the FTL version is supposed to be able to achieve.

I could be catastrophically wrong, for I am delving into things Man (well, me anyway) Was Never Meant To Know, but I think it goes that given the, I think the proper term isn't electrogravitic, it's gravitophotonic, force and the inflationary force, light is no longer- never actually was- the actual speed limit for the universe, only the, ah, ground state? of it we currently inhabit.

I think (for I am not certain) that the causal limit, beyond which time travel could be said to occur, is treated as the speed of the inflationary force, not the speed of light. Either that or he flat out was talking about time travel.


That and given the 25- tesla magnetic field I found mention of, would this not be spectacularly detectable?

[GrandMasterTerwynn]

Faster than light travel will invariably end up being time-travel in some frame of reference. Say you take a ship and you fly to Epsilon Eridani. You arrive eighty days later (from your frame of reference.) However, observers at Epsilon Eridani will not witness your departure from Sol for another ten years (the the information that describes your departure, i.e. photons and gravity waves, travels at the speed of light.) From their frame of reference, you've traveled ten years back in time, successfully sodomizing causality (your arrival at Epsilon Eridani from Sol magically occurred before your departure from Sol to Epsilon Eridani.) Sci-fi writers, however, handwave this little problem away all the time.

No. You merely outran your own light. How does that imply time travel?

There have been a number of threads around here which ask this exact same question. People with a far greater grasp of the particulars have given answers here, here, and here.

The short of it is that "outrunning your light != time travel" is a misconception that arises from the assumption that light is just a bunch of particles travelling at c, and everything exists under one master frame of reference, which in a Newtonian universe, makes perfect sense.

However, it doesn't work that way in a universe governed by relativity. There is no single master frame of reference. In our example, Sol and Epsilon Eridani exist in two different frames of reference. They don't share a common master frame of reference (ergo, no simultaneity.) Time is relative to whatever frame of reference you're using.

In one of the referenced threads, I refer you to the following explanation:

With many problems in relativity, the problem of FTL travel and causality boils down to "simultaneous events." In relativity, an observer defines his x axis to be the locus of all points such that, for all a, if he sends out a light pulse at the event at time t = - a, he will receive the reflection at t = a. This is because the light pulse spent equal time (from this observer's perspective) getting to the event as coming back.

Now, suppose the signal from your FTL communication device gets to a distant receeding galaxy instantly from your frame of reference. That is to say, if the galaxy is located at (t_0, x_g) in your coordinates, then if you send the FTL signal at (t_0, 0) [ie, here and now], then you can verify that your FTL signal got to the distant galaxy at (t_0, x_g) in your coordinates. Meanwhile, your friends in that distant galaxy has a simiar setup, and is able to verify that if they sent their FTL signal at (t_0, 0) in their coordinates, then they can verify that their FTL signal got to you at (t_0, - x_h) in their coordinates.



Suppose you want to ask your friends in the distant galaxy whether they see helicopters out their window, sending your message at event A. This event is simultaneous with event B, so your friends receive the message at B. They look outside their window and see that there are indeed no helicopters, and send a message back using their own FTL apparatus at event B (or very nearly the same event as B, but these galaxies are distant), which you will receive at an event simultaneous with their event B, or C.

Notice that event C lies in the past of event A, the initial message. Therefore, the event A caused the event C. If you resolved that you would send your message only if you did not receive the answer before you call, then you'd have a happy little mini-grandfather paradox!

As for avoiding such problems in hardish sci-fi, the principle is this: Relativity, Causality, FTL travel -- choose two. The only way to avoid causality problems when using FTL travel is to break relativity in some way when using FTL. The most straightforward way to do this would be to have some OTHER definition of simultaneity than what relativity uses.

This explanation applies to a flat spacetime, as defined by Special Theory of Relativity. An FTL ship, in STR, violates causality.

[Ryan Thunder]

Oh jesus, he doesn't understand relativity.

Ah, fuck you. I haven't read into it beyond the high level, because even that was enough to give me headaches on the spot.

PS Ryan, if anything even information appears from some frame of reference to have arrived before it left, that's time travel.

Okay, I'm sorry, but I really just don't get it. Why is it time travel if it only appears to have arrived before it left? It might appear to have arrived before it left, but it really didn't, did it?

I have the same problem with the speeding ship scenario; Spaceship leaves Earth at some fraction of c. From the spaceship, you can observe Earth, which is experiencing relativistic effects (shortening, etc). From the Earth's perspective you can observe the spaceship, which is experiencing the same relativistic effects. But near as I can tell, those effects are mutually exclusive. At the same time, neither frame of reference is incorrect...

[Stark]

That's the point of multiple frames of reference; things can appear different from two different observers, which is why this whole thing happens with FTL (since observation and everything but the ship is limited to c).

[Ryan Thunder]

That's the point of multiple frames of reference; things can appear different from two different observers, which is why this whole thing happens with FTL (since observation and everything but the ship is limited to c).

So, then, we have a paradox. Because from the ship's frame of reference, there is no time travel. And here all this time I was thinking that wasn't supposed to happen...

Okay, I think I get it. I'm used to thinking of the laws of physics as a sort of omnipresent, contiguous computer program.

So from the ship's frame of reference, there's no time travel. But from every other frame of reference, there is. Time travel violates causality, therefore this should be impossible.

Right?

[Darth Ruinus]

So from the ship's frame of reference, there's no time travel. But from every other frame of reference, there is. Time travel violates causality, therefore this should be impossible.

Right?

I think its from the ship's point of view, and its crew, they would see the outside world moving slowly.

[montypython]

Wormholes and similar phenomena are popular alternatives to the more typical linear FTL systems in fiction due to relativity.

[Formless]

Wormholes and similar phenomena are popular alternatives to the more typical linear FTL systems in fiction due to relativity.

Isn't part of Heim theory's appeal the fact that it is partially based on relativity? I mean, correct me if I'm wrong, but it couldn't exactly claim to be a unified theory if it wasn't.

Besides, Wormholes do nothing to combat the time travel problem, so I don't see how they are superior in any way to other forms of FTL. Nor do they work for every kind of sci-fi story. As I see it, Heim theory may still be out there in reality, but using it in fiction at least gives the linear FTL starship some scientific legitimacy in hard sci-fi.

[Ford Prefect]

Okay, I'm sorry, but I really just don't get it. Why is it time travel if it only appears to have arrived before it left? It might appear to have arrived before it left, but it really didn't, did it?

Except that's exactly what it looks like. To a person observing Epsilon Eridani from Sol, what they see is events that happened eleven years ago, as that's how long it takes for light to propagate from there to here. So imagine that you are observing the FTL ship disappearing into hyperspace. It will make the round trip between here and Epsilon Eridani in somewhat over four months at fifty times the speed of light, not counting any time they spend in-system doing whatever it is you do there. However, consider that by the time you observe them leaving Epsilon Eridani, the ship would have arrived eleven years ago.

[Ryan Thunder]

Okay, I'm sorry, but I really just don't get it. Why is it time travel if it only appears to have arrived before it left? It might appear to have arrived before it left, but it really didn't, did it?

Except that's exactly what it looks like. To a person observing Epsilon Eridani from Sol, what they see is events that happened eleven years ago, as that's how long it takes for light to propagate from there to here. So imagine that you are observing the FTL ship disappearing into hyperspace. It will make the round trip between here and Epsilon Eridani in somewhat over four months at fifty times the speed of light, not counting any time they spend in-system doing whatever it is you do there. However, consider that by the time you observe them leaving Epsilon Eridani, the ship would have arrived eleven years ago.

And there is no omniscient, objective frame of reference from which you can definitively say that it didn't arrive before it left, right?

[Ariphaos]

And there is no omniscient, objective frame of reference from which you can definitively say that it didn't arrive before it left, right?

You can define one. You just need to be cognizant of the consequences. If you think "x times c" where x > 1 makes any sort of sense in such a Universe, you have not remotely thought it through enough.

[Ryan Thunder]

And there is no omniscient, objective frame of reference from which you can definitively say that it didn't arrive before it left, right?

You can define one. You just need to be cognizant of the consequences. If you think "x times c" where x > 1 makes any sort of sense in such a Universe, you have not remotely thought it through enough.

Well, of course it doesn't make sense. Plugging v => c into Einstein's equations gives you either infinity or imaginary results, IIRC.

Right, so, faster than light travel is time travel and therefore violates causality, therefore it is impossible. This is also true for wormholes.

So we're strictly limited to some miserable fraction of c. So much for galactic empires.

[Ariphaos]

Well, of course it doesn't make sense. Plugging v => c into Einstein's equations gives you either infinity or imaginary results, IIRC.

Right, so, faster than light travel is time travel and therefore violates causality, therefore it is impossible. This is also true for wormholes.

So we're strictly limited to some miserable fraction of c. So much for galactic empires.

That's flawed on two premises.

The most obvious one is why limit a galactic empire to current human timeframes. Sunshine and happiness makes for a very long arm and though you can cope with a single aggressor in theory, it is possible for a galaxy-spanning empire to pacify rogue systems.

The other one involves thinking outside the box on the largest scale imaginable - there can be no fixed frame anchored within the scope of our Universe, so you go outside of it. That's the funner answer, though it's difficult to express the enormity of the task in such a situation. 100 * c makes no sense, but you can use it as a shortcut - "The journey from Sol to Alpha Centauri took fifteen days in Alpha Centauri's frame of reference."

Which says nothing about how long it took the ship from its own frame of reference, so you need to consider that as well.

As a sortof-third premise, you can make FTL communications occur in such an energy-intensive and space-spanning manner as to make the question of whether it violates causality moot. If your 'ansible' requires the power of a large star and a parsec-spanning particle accelerator, these things are not going to be moving at great speeds with respect to one another, and any test at such scales is a purely hypothetical exercise, especially if it takes four years to transmit or receive a signal. "Okay, accelerate W Cephei to .4 of c, and protect the twenty-light year long accelerator from particle collisions..."

[Formless]

I have another question. The rule in Hard SF if usually "relativity, causality, FTL: pick any two." If you are basing your FTL on Heim theory, which two do you get? Causality, or Relativity?