Time Travel in the Iron Empires [Majory Geekery]

I just read Charles Stross’ Singularity Sky. I wouldn’t necessarily recommend it (I’d recommend some Vernor Vinge or Banks instead), but it certainly got me thinking.

Help me understand why distortion doesn’t end the universe in Iron Empires.

Nearly every interstellar ship in the Iron Empires is equipped with a device that can alter the flow of time. According to what I boiled down from Chris’ notes, time is affected in a manner that makes the ship move really, really fast.

Let’s assume that this effect is created by a local phenonemon that makes the ship move faster in time relative to its destination and its desired point of arrival.

Wikipedia has this to say on the matter:

So Chris’ distortion mechanism moves an object through space and time. It’s a drive mechanism and a time travel device.

Okay, so if I’m moving at near-C speeds, time stays (theoretically) relatively lifelike for me, and moves at an accelerated pace outside of my near-C capsule. In other words, if I describe an arc of one light year of distance beginning and end on Earth, moving at a rate of .99 light years per year, I age .99 years while time on earth has advanced much farther, right?

In the Iron Empires, that’s sublight expansion, right?

Well, let’s lay out a major assumption in the IE:
Using the distortion drives, the effects are localized. (This is standard FTL handwavium.) This is supported by the Novikov Principle. See below for more on that.

Okay, so we have FTL handwavium drives. Cool. But they’re still time travel devices. And this is what I’m after: Can these devices create closed timelike curves? In other words, it’s theoretically possible to travel in time and bump into yourself in the past or in the future.

I’m humping through interstellar space, my drive goes burp as another time traveling device unexpectedly passes through my coordinates. I start her up again and take off at a faster rate to make up lost time. Can I overtake myself? Can I overtake the alternate version of me who didn’t burp when I crossed paths with the other time traveling device? Probably not. The easy answer is “no parallel universes.”

Apparently, this is called the Novikov Self Consistency Principle:

We shall embody this viewpoint in a principle of self-consistency, which states that the only solutions to the laws of physics that can occur locally in the real Universe are those which are globally self-consistent. This principle allows one to build a local solution to the equations of physics only if that local solution can be extended to a part of a (not necessarily unique) global solution, which is well defined throughout the nonsingular regions of the spacetime.

But wait, can I loop back and overtake my light cone? Why not? Light moves at a constant. I’m moving at a constant x10 or something.

According to those theoretical physicist nuts, it seems that on a quantum mechanical level, you can’t go back in time and kill your grand dad so that you were never born. In fact, I don’t think you can go back in time and do anything that would preclude you from ultimately traveling through time. But I could be wrong.

Of course, that doesn’t mean you couldn’t travel time and fuck someone else who is not part of your closed timelike curve.


More madness

Shape of absolute future
According to Hawking and Ellis, another remarkable feature of this spacetime is the fact that, if we suppress the inessential y coordinate, light emitted from an event on the world line of a given dust particle spirals outwards, forms a circular cusp, then spiral inwards and reconverges at a subsequent event on the world line of the original dust particle. This means that observers looking orthogonally to the direction can see only finitely far out, and also see themselves at an earlier time.

Time and light travel in curves or waves.

It’s theoretically possible, using the distortion drives, to move faster than light, arrive ahead of the light’s curve in time (but still within its cone) and look behind you and see what happened in the past. So if I can move at C+, I can loop back and intersect my C- slow moving self. Uh oh. I’m simply talking about making a physical loop in space now at a velocity so fast that I can intersect with a slower moving body who left at the same time.

Okay, now what good does that do us? Well, can I use my distortion drive to travel so fast that I close the curve into a loop and then reappear in my line after I left but before another event transpired?

What if I use the above method to spot which planet a vaylen fleet will invade, go back and close the curve, and, since I can’t save the planet, I destroy it? Well, what if the Vaylen had sent scouts moving faster than light to the planet and they see me depart on a closed timelike curve. Can they then move faster than me in time and catch me and stop me? Can they move faster in distortion than I’m moving, close a curve and jump to my home planet and destroy it before I left?

If not, why not? Distortion drives are time travel devices!

Distortion drives are nominally FTL drives and don’t let us muck with time, but for me, they’ve always seemed to be the irresistible key to a Pandora’s Box.


The other question about FTL drives is why don’t societies that have them use them as weapons. A HeX drive unleashed on the surface of a planet should crumble it. Not to mention just the power source alone would need to be quite potent. Like small star level.

Well, according to IE canon, these drives can only function in a vacuum. They “crash out” when introduced to non-vacuum environments.

Uhm, i smell Forever War :wink:

But what if the quantum physics isn`t last step in a science and we will have rewritten all theories by the end of next decade?

Fair enough. You could still make an “expansion torpedo” to fuck with ships, though.

Well, Stross had to resort to God to keep people from dicking with causality – I can’t remember if that was Iron Sunrise, Singularity Sky and/or Accelerando. I think the first two are sequels/prequels. Wasn’t that the one with the Godlike entity that everyone was afraid of when they use FTL?

I think you could probably safely adopt a “It’s time travel, but so what?” approach in the Iron Empires, given the extreme decay of technology. If you’re going FTL but nobody has sensors/radios/telescopes that can, say, actually pick up information from “the future” (your past), wouldn’t that pretty much handwave it away?



Everyone else: Zzzzzzzzzzzzzzzzzzzzzzz, snort, what? Did you say something or should I just go back to sleep?

So you’re looking for, what, more provocative answers?

The thing in SS or IS…whichever, I can’t keep 'em straight…about the planet receiving way, way advanced warning about the killer asteroid was neat. They get FTL information about the impending apocalypse but, like, generations of people live and die before it actually arrives. And then using the asteroid as a bargaining chip, with perhaps some opportunity to blow the planet-killer before it gets there, very cool. Possibly very Vaylen.

I don’t have a firm sense of how truly high-tech the Vaylen are, though. Seems like something one noble house might do to another one.

So we’re talking about time travel that’s allowable via what we already know about Iron Empires tech, right? Like, no extrapolating or writing in additional non-Moeller-approved materials.

It seems like something that’d either happen all the fucking time, or is so expensive and difficult to plan out that it happens only very, very rarely. Or only by mistake. The Vaylen probably figured out it’s not worth the effort the minute they read all about it in the old super-tech archives they grabbed.

I liked in Iron Sunrise that these questions came down to either a) matters of law and honor or b) God stepped in and fucked up your shit if you got too sassy with the closed timelike loops. Leaving God out of the equation, you’re left either with gentlemen’s agreements to leave it alone, some facet of time travel that keeps you from re-entering your own light cone, or a perpetual self-referential war that constantly loops in on itself.


I’m definitely looking for a little extrapolation in the Moeller-verse. He’s equipped ever ship with a time travel device. What are the implications of that?

There’s a video camera at the edge of near/deep space pointing at a flight lane. A ship passes by the video camera, accelerating to C. That same ship accelerates to 100x C and loops back and stops in front of the video camera before the light from its original exit reaches the video camera. The ship then moves on at sub-C speeds. What does the video camera see?


Good luck maneuvering a ship back to its starting position as it goes 100C.

But assuming you can. Assuming the hEX basically just repositions you inertialessly somewhere else in spacetime. And I guess you’re saying we should assume that there’s nothing fundamental to time travel that prohibits you from looping back on yourself. I mean, in your videotape example, you’d see the subject in position at some point prior to its scheduled appearance.

It might be that hEX sends out some kind of nasty wave or pulse or whatever, that’s impenetrable by other hEX effects. That could be very interesting! Like, set up bogus hEX launches at or near major arrival points or strategically useful locations in space – a literal hEX-proof barrier. And using time travel to pre-empt the big wave might come with its own problems. Sublight harmonics or some other handwaviness that nukes out both the original hEX engine and the pre-empting one. Given they’re absurdly expensive in the setting, you probably wouldn’t see munitions factories pumping out hEX-generating torpedoes.


But hEX engines can’t be THAT expensive, there’s plenty of ships out there. Hell, a court chronicler can afford one… And surely, some lunatic warlord would rape a hundred worlds in order to build a couple of hEX warheads…

What prevents me from building a vacuum generating field and then wrapping that around a missile that hits a planet before they see it launch?


Sorry guys, I`m not a man from R&D, and you know - if I want to see what happens with world, when dimensions&galaxies collides, I watch Gurren Lagann.

But seriously, it doesn`t match to my vision of IE setting - same with nuclaer warheads, BC weapons and stuff from Alastair Reynolds universe :wink:

You don’t even need HeX, as sublight stuff is the same tech, and those are a dime a dozen. Strip the engine out, strap it to a magnet-mine and set it headed towards a “space lane” or whatever you want to call it. It locks onto a ship and fires up once inside a certain range. Hilarity ensues.

Huh! I always had it in my head that hEX was supertech from a bygone age. I don’t know why I thought of it that way; nothing in the book or the TPBs suggests it. There probably is supertech drive technology from a bygone age, but hEX ain’t it.

So basically we’re talking about time travel as a WMD (i.e. the premise of all the wartime laws in Iron Sunrise, right?).

I’m not strong on the physics side of all this, other than we’re talking about very, very energetic devices. I would assume that purpose-built weaponry of the time would be far more efficient than when the same high-energy tech is applied to interstellar travel. If you’ve got the juice to spin up to 100xC and producing that effect is trivial (as trivial as, say, powering a nuclear submarine today), planet-busting weapons are probably achievable. Maybe even sun-busting weapons.

But who’d use them? What would be the point, other than to fry a system that’s totally and irrevocably lost to the Vaylen?

The logical/informational side of practical time travel seems more interesting, frankly.

So now we’re into both sides of a conflict – at least space conflict – pre-scouting battlefields. But by observing the battlefields, you’re also changing them, so that seems like a lost cause. I’m not sure anyone ever wins the “I saw you first” game at that point. I guess, if hEX is this energetic, there’ll be signs as you first arrive in a battlezone that the other side has already arrived and is observing you. But the observers can’t be everywhere and space is really big, so maybe just the act of having FTL battlefield observers forces each side to avoid the observed areas. It’d be a way to cordon off high-value areas, right? Just send an observer to the spot a few hours before, let the hEX signature show off their presence, and no way no how is the enemy gonna show up there. So by default, everyone always arrives at a battle in some shitty, suboptimal way.

If your FTL observers are maneuverable/fast enough in real time, they could get a look at things happening and report back in advance. But, causality being what it is, I don’t know that they could do anything about it. Your scouts see the big Vaylen troop carrier latch onto your command ship and disgorge troopers and a few billion worms, but so what? If you know about it in advance you couldn’t stop it from happening – but, I suppose, you could make preparations outside your FTL scout’s ability to perceive and report back to you.

It seems like battles might look a lot like those old Mad Magazine Spy vs. Spy comics: I dock your command ship! But I know it’s going to happen so I flood the air with poison gas! But we knew that was gonna happen so we came in with air masks! But we knew you would have air masks so we made the gas flammable! Etc. etc.


IIRC, the knowledge that created expansion drive technology is lost, but there are still factories burping the stuff out on a regular basis. There’s just not really anyone around that knows the theory of how they work, or if they do, they are very secretive about it (think Ixians in Dune).

Time travel theories never fail to bring out the weirdest, most bizarre assumption on the part of people talking about them. You have to watch out for those.

Okay, so Moeller Distortion drives manipulate time to make ships go really fast. How is that “time travel”? They are still traveling forward in time like everyone else, right? How do they go backwards?

As for the light waves generated - who uses video cameras? I would think the IE would have sensors able to detect and extrapolate the interrupted/deflected light waves and re-create a chronology. And how does that example have anything to do with time travel?

Weaponization is easy - you just have to defeat sensors connected to anti-incoming ground-to-space weapons. But we already had a conversation about why you wouldn’t want to destroy a planet in a much earlier thread.

Better uses for the drives.

Slap an environment system, bolt on some fusor batteries, and then raise some rich merchant prick’s sons and nephews to the Hammer. Then you have resuable weapons platforms, social obligations, and big fucking pile of cash.

If you shoot a HEx drive at another HEx drive and it works then you end up being down two HEx drives. If they are rare then that is just retarded; if they are relatively common then you probably don’t want a battle of attrition where you spend one for each one you destroy.

Besides! Who is flying this damn thing? Why don’t I just distort behind an asteroid and let the thing smash into the wrong side of a fuckton of ice and rock? Putting good enough Avatars into these things just ups the cost more, making it less and less of a good economic option. At least contemporary UAVs are not designed to blow the shit out of themselves.

ASIDE: We have biochem weapons in our current Sub Index game. The military jerks in Iron and Anvil just button down and the hapless conscripts and civilians all get their hideous death on.

This makes a the collection of viable labour resources from neutral and enemy states a major war objective - before the crippling agents start raining down.

As things progress I expect a lot of euthanasia camps being set up to deal with the ridiculous volume of chemically maimed people. Something to look forward to.

(I blame work for this line of thinking.)

(Hi insmouth and lexifab! I hope this gives you a clue about my Innundate actions…)

Thanks, Sir Isaac. Unfortunately the assumptions you’re making in this post were disproven by Michaelson and Morley in 1907. There’s no fixed frame of reference to define how fast time flows, or in what direction, so if you can shift your frame of reference faster than the speed of light, that’s time travel. Read up on your relativity and enjoy some thought experiments about trains for more on why.

UAV=cruise missile. Cruise missiles aren’t smart, no avatars, but they still manage to hit their targets on occasion.

I don’t understand how you move a planet behind an asteroid to dodge an incoming warhead that you can’t see. I’m looking at IE canon here. We know we have time travel devices. We haven’t seen any instance of a time distortion detection device, have we? I know we can just handwave one in, but I’m looking for interesting, logical situations here based on the context provided. I can handwave any bullshit SF I want, but I don’t want to!

What Devin said!