Jumplines and stellar movement

[isf]

Originally Posted by ericthered

Looking at the chart, 10,000 looks plausible, but I have my doubts about 1,000.

There was a suggestion in one of the jumpline threads about making some jumplines more robust than others; I'm approximating that with shorter duration lines, though it could be modeled with a penalty to using faint lines.

Originally Posted by ericthered

On the other hand, if existing connections matter, you can have a single change butterfly its way through the entire network. And you can even have civilizations kill their trade networks the first time someone thinks they can make an artificial one.

That would seem pretty foolish unless you had a working artificial one. I haven't decided if jump gates will be possible, but I'm inclined to say yes at higher tech levels.

[Johnny1A.2]

Originally Posted by Fred Brackin

In Michael McCollum's Antares Dawn (plus 2 sequels) there was a big network around Antares....until that went supernova.

https://www.amazon.com/Antares-Dawn-...s%2C170&sr=8-1

Ir's quite a good book and I recommend it on general principles but it's a very good model for jumpline networks.

Seconded. I kind of think McCollum got his FTL concept from Pournelle's stories, but it's still an excellent example of how such things could work.

Note, though, that placement relative to the star matters hugely. Both Pournelle and McCollum put their jump points way, way out from the star, in most cases, and then make up for that by giving the characters ships that can routinely accelerate at multiple Gs for days on end. In both sets of stories, the heroes have ships that can regularly climb up to 5 of 6 percent of c, and then climb back down on a single load of fuel/propellant.

That solves the time problem for getting to and from gates in the outer part of a star system, because the ships can cross a star system in a few days. The down side of that, unmentioned in the books but relevant to an RPG setting, is Jon's Law. Multi-thousand ton ships that can get up to 5% of c are super-duper WMDs. Take INSS MacArthur from The Mote In God's Eye. At one point in the book it accelerates up to .06c and back down again, meaning it could potentially get up to .12c or so if it wasn't worried about slowing down again.

If MacArthur masses 10,000 metric tons (which is quite modest for such a large vessel), then at .12c it would have an impact energy of 1.5 teratons if it struck a habitable world. That's civilization-shaking. (Actually, it's worse, because I ignored relativity and just did a Newtonian calculation, but at .12c relativistic effects begin to become noticeable.)

If you don't want PCs having access to teraton-scale WMDs, you can avoid the problem very simply, by moving the jump portals in closer to the planet, enabling more restrained ships to come and go in reasonable time periods without Jon's Law becoming a major issue.

Another unnerving thing about star-to-star jump points, at least in the McCollum series. It's casually mentioned in a later book in that series that 95% of all stars lack jump points. This makes them effectively unreachable and means that any civilization orbiting such a star is utterly cut off. The human race was lucky in that Sol had 2 jump points, but it's easy to imagine the frustration of a race that has learned by theoretical physics that jump points exist and FTL is possible...but has no jump points. If 95% of all stars have no jump access, that scenario is probably common...

[Dr. Beckenstein]

Originally Posted by Johnny1A.2

Another unnerving thing about star-to-star jump points, at least in the McCollum series. It's casually mentioned in a later book in that series that 95% of all stars lack jump points. This makes them effectively unreachable and means that any civilization orbiting such a star is utterly cut off. The human race was lucky in that Sol had 2 jump points, but it's easy to imagine the frustration of a race that has learned by theoretical physics that jump points exist and FTL is possible...but has no jump points. If 95% of all stars have no jump access, that scenario is probably common...

This could be a fascinating campaign. The "trapped" civilizations can just watch with envy through their telescopes FTL ships jumping around other stars. Than, envy turns into relief as they watch interstellar wars unfolding. And than, relief turns into fear as they discover that, thanks to the movement of the stars, their own star will get its own jump point, one that will lead directly into the combat zone, where a war is fought by empires that dwarfs them into every regard ...

[isf]

Originally Posted by Dr. Beckenstein

This could be a fascinating campaign. The "trapped" civilizations can just watch with envy through their telescopes FTL ships jumping around other stars. Than, envy turns into relief as they watch interstellar wars unfolding. And than, relief turns into fear as they discover that, thanks to the movement of the stars, their own star will get its own jump point, one that will lead directly into the combat zone, where a war is fought by empires that dwarfs them into every regard ...

I like this, though I haven't decided on whether or not many civilizations know about the jumplines lifespan.

[johndallman]

Originally Posted by isf

I like this, though I haven't decided on whether or not many civilizations know about the jumplines lifespan.

It's an obvious question to investigate once jumplines are discovered.

[ronwit]

Steve White's Disinherited has a jumpline network collapse at the end of the first book. It saves the humans form the more advanced enemy aliens. But it also dismembers their own civilization.

[Irish Wolf]

John Scalzi just published The Last Emperox, third and presumably final series in the Collapsing Empire trilogy. In that one, the passage is called the Flow, and is only accessible at certain "shoals". The Flow is moving away from the shoals, isolating each of the worlds of the Empire; problem there is that the Empire has been cut off from Earth for something over a thousand years, there's no known Flow path back there, and the only world of the Empire that's more than marginally habitable is the least-regarded world, End. The others all became wealthy on interstellar trade - which is about to collapse, leaving everyone to starve slowly.

In the last volume, The Consuming Fire, there were hints at a possible successful resolution of the situation. I have TLE on order at the local library, but of course they're closed down for the nonce, so I have no idea what's going to happen.

[Pragmatic]

The collapse/disruption of the hyper levels is a plot point of the Uplift Storm trilogy (David Brin, Uplift universe).

[YankeeGamer]

Originally Posted by Dr. Beckenstein

This could be a fascinating campaign. The "trapped" civilizations can just watch with envy through their telescopes FTL ships jumping around other stars. Than, envy turns into relief as they watch interstellar wars unfolding. And than, relief turns into fear as they discover that, thanks to the movement of the stars, their own star will get its own jump point, one that will lead directly into the combat zone, where a war is fought by empires that dwarfs them into every regard ...

The alternative is simple: The "trapped" civilization figures that there HAS to be another way--breaking the speed of light IS possible, after all. So, they push physics where no one has ever pushed it before...and perhaps figure out another way. (Or figure a way to hasten the reconfiguration of the jumplines.)

They build enormous ramscoops, not to GO places, but to accumulate Hydrogen in unholy amounts. (If they have gravity manipulation, so much the better.)
Then, IGNITION. If the jumplines don't reconfigure, either add more fuel, making a bigger star, or build another one. (Or just start adding planets.)

<"Simple" is not the same as "easy."

[ak_aramis]

Lois Bujold's Vorkosiverse has some jumplines that have closed then reopened due to stellar orbital dynamics - Barrayar was isolated for a couple centuries as I recall.