# Help! Has Jack Campbell completely messed up or have I?



## Vertigo (Aug 27, 2017)

Not sure if this is really the correct place for this and if a mod wants to move it then please go ahead! 

I am currently reading a Jack Campbell and he is usually very meticulous about his astrophysics but I'm pretty sure he has completely messed up in this book with regard to the behaviour of light. Not only that but now I'm thinking about it I suspect I have come across the same error in other books by other authors. That is of course if it is a mistake and I haven't completely lost it.

This might be hard to describe clearly but I'll give it a stab. Early on in the book Campbell spends significant time (in fact he rather labours the point) explaining that although the speed of light if pretty darn fast in the context of distances in space it can seem pretty darn slow. Which is correct but he then seems to completely mess up, twice in fact as he has the same thing happen earlier on in the book.

It involves three fleets of warships: an 'Enigma' fleet, a 'Syndicate' fleet and the Midway fleet, which is where the POV is. The Midway fleet has just arrived in the star system and they immediately see the Syndicate fleet that has been there for some time and is around three light hours away. All of a sudden the Syndicate fleet appears to turn tail and run and the Midway fleet surmises that they have seen another enemy appear farther away and the light from that event has not yet arrived at the Midway fleet. Which turns out to be the case; an Enigma fleet has arrived and as soon as the light of their arrival reaches the Syndicate fleet they turn tail.

Now there's my problem. The light from the Enigmas reaches the Syndicates and they turn tail then three hours later the light showing them turning tail arrives at the Midway fleet. But in the book they still don't see the Enigmas for several more hours. But, hang on, the light from the enigmas has reached the Syndicates and then they act. Now let's assume they act immediately (it's even worse if they delay), then the light of their action starts on its way to the Midway fleet but the light from the enigmas is also on its way, having passed the Syndicates it's not going to pause and wait a while, nor is it going to go slower, so in fact the light of the enigmas arrival and the Syndicates action should reach the Midway fleet simultaneously. That is assuming it is a direct line from the Midway fleet to the Syndicate fleet and on to the Enigma arrival. Any other geometry would actually have the light of the Enigmas arriving _before_ they see the Syndicate reaction.

Sorry for the long post but I'd love it if someone could either confirm I've not lost it or explain how I've got it wrong. Incidentally this takes place in the book Shattered Spear for anyone who has it and wants to check the 'facts.'


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## Serendipity (Aug 27, 2017)

Are there any interesting celestial objects around to significantly slow the speed of light down? Thinking dense-ish nebula or peculiar black holes where the positions of the fleets make a suitable triangle i.e. the dense nebula or whatever is in line of sight between the Enigma fleet and the Midway, but no such object exists on the lines of sight between Midway and Syndicate or Syndicate and Enigma....

This, if it hasn't been done before, which sounds as if it must have, could make for some interesting sciencey science fiction... off to pontificate...


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## Paul_C (Aug 27, 2017)

I'd agree - unless somehow the light from the Enigma fleet is obscured by the Syndicate fleet, it should arrive at the same time, and if it is obscured then as soon as the Syndicate fleet moves out of the way the Enigma fleet would become visible, not hours later.


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## Ursa major (Aug 27, 2017)

I'd also agree...


...unless the geometry is such that there's an object (O, a planet, say, or a moon) between the position of the Midway fleet (M) and the position of the 'Enigma' fleet (E) that does not obscure E from the Syndicate fleet (S) AND that, after a few hours, movement of the three (O, M and E) provides a direct line of sight between M and E.


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## Vertigo (Aug 27, 2017)

Nope no planets or anything else in the way; this is all within a star system and the Enigmas are not quite exactly in between the Midway fleet and the Enigmas. Also Campbell is very explicit about saying that it is just the light delay. Another hint as to how he might have got it wrong is that they see the light of the enigma arrival  2 hours later and Campbell states that there is two light hours between the Syndicates and the Enigma. I'm glad it seems I'm not going completely barmy and that Campbell just didn't think it through carefully enough. There was another scene earlier when they saw one of their ships suddenly head off towards a jump point but hadn't the light of whatever had set them going hadn't yet arrived so we had no idea why they had set off. On both occasions this was a significant tactical factor which is really annoying.

If I can find the time tomorrow (likely since it looks like we're going to just get loads of rain tomorrow) I'll try and cut and paste the relevant descriptive passages and see if you can see any flaws in my logic.


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## Ursa major (Aug 27, 2017)

Vertigo said:


> and the Enigmas are not quite exactly in between the Midway fleet and the Enigmas


I assume you meant





> and the Syndicate are not quite exactly in between the Midway fleet and the Enigmas



But, basically, M should see E arrive before they see S react (even if S reacted instantaneously), as the distance ME is less than (SE+MS) where MSE is not a straight line.


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## Vertigo (Aug 28, 2017)

Ursa major said:


> I assume you meant
> 
> But, basically, M should see E arrive before they see S react (even if S reacted instantaneously), as the distance ME is less than (SE+MS) where MSE is not a straight line.


Oops, you are right, of course. That's what I meant to type, but too late for me to correct now . And on your second point I'm in complete agreement. if it is a straight line then they should see the Enigma arrival and the reactions simultaneously (assuming simultaneous reaction) and for any other geometry they should see the arrival first, before the reaction.


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## Vertigo (Aug 28, 2017)

Okay here are the various bits of text as Campbell wrote them:

The Syndicate flotilla, which was about three light hours from the newly arrived Midway flotilla and barely twenty light minutes from the formerly inhabited world...The Syndicate flotilla is maneuvering. It can’t be in response to us. They won’t see us for another two and a half hours...*They must have seen something that we haven’t yet*...Whatever they saw is way on the far side of the star system from us...The enigmas. The jump point we saw that ship of theirs using is over there...I don’t want to go any faster until I know more about what the enigmas are doing. We should see them within a couple more hours...It took another two hours, as they watched the hours-old movements of the Syndicate flotilla toward an unseen enemy, before the light showing the enigma ships finally reached the Midway flotilla.

That lot is spread over about 4 or five pages with lots of chatter (and time) in between. The bolding is mine.

So we're in agreement that Campbell has it totally wrong in this case?


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## Brian G Turner (Aug 28, 2017)

I figure he tripped up over the individual light distances and added them up, instead of making them relative.


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## Paul_C (Aug 28, 2017)

The only thing I can think of that might work, is that the Enigma fleet is directly on the other side of the sun to the newly arrived Midway fleet. The light the Syndicate fleet has seen cannot be seen by the Midway fleet until they are in a position where the sun is not in the way.


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## Vertigo (Aug 28, 2017)

Brian G Turner said:


> I figure he tripped up over the individual light distances and added them up, instead of making them relative.


That's what I think as well. But he actually did exactly the same earlier in the book. 


Paul_C said:


> The only thing I can think of that might work, is that the Enigma fleet is directly on the other side of the sun to the newly arrived Midway fleet. The light the Syndicate fleet has seen cannot be seen by the Midway fleet until they are in a position where the sun is not in the way.


That would work but he actually says: "It took another two hours, as they watched the hours-old movements of the Syndicate flotilla toward an unseen enemy, before the light showing the enigma ships *finally reached* the Midway flotilla."


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## Paul_C (Aug 28, 2017)

I was merely offering a way of looking at things whereby the description makes some sense, if you'd prefer I'll just say that you are correct and Jack Campbell is a ninny.

A ninny !


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## tinkerdan (Oct 28, 2017)

Yes that's a flaw in the story.
If the second fleet was not visible until several hours later then no matter where they were in relationship to where the departed fleet was they could not have been the cause of the fleets departure because that fleet could not have seen them at that time most likely because they weren't there at the time the other fleet departed.  

If the second fleet and its  light was x light hours behind the light of the first fleet then they would have arrived at the same time the fleet disappeared but the fleet wouldn't have seen them until x light hours after and by then they were already gone. That's assuming they were directly in line from the third fleet's view of the light on the other side of the first fleet.


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## Foxbat (Oct 28, 2017)

I'm finding it hard to believe that fleets so advanced as to travel through vast distances of space would rely on line-of-sight at all


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## Vertigo (Oct 30, 2017)

Foxbat said:


> I'm finding it hard to believe that fleets so advanced as to travel through vast distances of space would rely on line-of-sight at all


What else would you rely on? Nothing moves faster than light.


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## Foxbat (Oct 31, 2017)

Tachyons?

Or perhaps the jump engines might leave some kind of post-jump evidence. Also, if the engines can circumvent the speed of light, why not the detection systems?

You could have some kind of Jump Detection Emission Radar (JUDER). You could even add a bit of tension by the emission particles having a half-life and the newly arriving ship crew having to furiously back-calculate based on these detections to try and prevent the possibility of ambush.

P.S. I should also admit that I gave up after book four because I found the whole thing becoming increasingly tedious and long-winded so I'm definitely not his biggest fan.


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## ralphkern (Nov 1, 2017)

Yeah, they should have seen the manouvering and the Enigma's at the same time. It sounds like he's broken it down in the wrong way, and viewed each element acting in isolation, then assuming then that as soon as a fleet is visible, you view it real-time (which is wrong, as the observer would see it with a light speed delay). Even if the Enigma fleet was opposite, then the Syndics manouvres and the Enigmas should be visible at the same time. 

The only solution which immedietly occurs (and it has been awhile so I might be wrong) is as I dimly recall, didn't the Enigma's have excellent stealth capability? That might provide some answer if the Syndics are much closer, they may have been in a position to defeat that while the Midwayers were still too far out?

Alternatively, geography has been used by factions before. The one where that Syndic battleship hid behind a planet but you say that isn't an issue in this problem.


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