Ring Worlds and Dyson Spheres revisited.

[Orr]

Several Traveller sources tell thet gravitics work by interacting with gravitons, those being absent in this centripetal force siumlated gravity, do gravitics work on them?

A ringworld is made up of matter and ALL matter exerts a gravitational field so there are "gravitons" for Traveller's magical gravitics to manipulate.

Which is the safe jump distance (the 100 diameter equivalent) in such worlds? Gavity being simulated, there's no true gravity well for them...

As previously explained, a ringworld being made up of matter will have a gravity well. However, the 100D limit is not gravity based.

As for what a ringworld's 100D limit would be, Aramis already did the math for you.

 

[rancke]

As previously explained, a ringworld being made up of matter will have a gravity well. However, the 100D limit is not gravity based.

Well, it is and it isn't. It's been stated that jump limits are caused by gravity. Unfortunately, Marc Miller insists that the effect works in a way that makes a lot less sense than the tidal force model does. Indeed, I'm tempted to say that it makes no sense at all, but that might be going too far.


Hans

 

[mike wightman]

There is an interesting death in Consider Phlebas.

A merc jumps off the superstructure of a ship , expecting his contragrav to safely allow him to fly down to the deck below.

Trouble is the ship is floating on the ocean on an orbital - a mini-ringworld.

With no 'real' gravity to work against the grav belt doesn't work - splat

 

[aramis]

There is an interesting death in Consider Phlebas.

A merc jumps off the superstructure of a ship , ecpecting his contragrav to safely allow him to fly down to the deck below.

Trouble is the ship is floating on the ocean on an orbital - a mini-ringworld.

With no 'real' gravity to work against the grav belt doesn't work - splat

In Traveller, it's more like the 0.01xRating for deep space use fails to slow him fast enough.

But note also: The limit for gravitics is 10 diameters.

 

[GypsyComet]

The description of Northstar makes it sound like a cross between Niven's Ringworld and Chalker's Well World, or the Lactran zoo world from the Star Trek Log series (novelizations of the Animated season, in a few cases extended past the episode).

 

[robject]

I have questions...

(1) What mission/purpose could possibly require a ringworld?

There are easier and cheaper ways to colonize worlds, do research, protect people, attack other people, flee the galaxy... and it seems there are few more effective ways to put all of one's eggs in one basket, in a stellar sense, wouldn't you say? You're one maghiz away from annihilating trillions of people...

(1a) Now if you assume that by TL 27 ringworlds are just "easy enough to build" and "easy enough to use", then the mission/purpose thing is less important. And one might see lots of them (how populated they might be is another matter entirely). Basically the SUV of the Ancients period: sure they're inefficient gas-guzzler super-luxury beasties that are far larger than they need to be, but hey, everybody's got one, and they sure are rooomy, so...

(1a.1) Of course, you can't say that there were lots and lots of them in the Ancients period in Charted Space, because most systems have planets, don't they? There are apparently a disproportionate number of asteroid belts, which means they blew up each others' planets, not ringworlds. So, Rosette Worlds, yes. Single very impressive worlds, yes. Ringworlds, eh, one per sector, perhaps.

(1a.1a) How MANY planetoid belts in the Spinward Marches are presumed to be from the Final War? Anyone know?



(2) The ringworld at Leenitakot is unfinished, but its existence and its extreme age proves that its technology is there and functional, right?

Sure it's unfinished, but I had a thought tonight: it's not the atmosphere, land, water, and environment that's important about a ringworld. Rather, it's the technology along the rim. Therefore, Leenitakot could be extremely valuable and important.

 

[Orr]

(1) What mission/purpose could possibly require a ringworld?

It sort of fits in Niven's setting. You've got virtually immortal, hyper-intelligent, uber-paranoid Pak Protectors solely focused on protecting/growing their bloodlines. They have neither FTL drives or "radio" so everything they want to protect needs to be "close".

They've put all their eggs in one very big basket because, in their hubris, they believe they'll always be around to protect those eggs.

In a setting with FTL, however, ringworlds make damn little sense.

You're one maghiz away from annihilating trillions of people...

Oddly enough...

Spoiler:

... that happens to a certain extent in one of Niven's Ringworld sequels and because the event is a conscious decision to kill a relatively lesser number of sentients to save a larger number of sentients, the Pak Protector involved find they cannot perform the act. Instead they manipulate things so a human is given the choice.

(2) The ringworld at Leenitakot is unfinished, but its existence and its extreme age proves that its technology is there and functional, right?

I never liked that mention of an "unfinished" ringworld in Challenge magazine's Hinterworlds Sector material. It was very poorly thought out on several levels.

Sure it's unfinished, but I had a thought tonight: it's not the atmosphere, land, water, and environment that's important about a ringworld. Rather, it's the technology along the rim. Therefore, Leenitakot could be extremely valuable and important.

And that's one of the main reasons the Leenitakot ringworld idea seemingly wasn't even slightly examined before being crammed into canon. The technology required to build a ringworld - whether it's unfinished or not - is so far in advance of "everyday" technology in the OTU that Leenitakot should be a primary target of any race, state, empire, etc. with the ability to travel there.

And yet a relatively tiny Minor Race pocket empire operating at a TL C, the Outcasts of the Whispering Sky, somehow keep even the Major Races at bay and prevent any expeditions to Leenitakot.

Depending on the era, there should be a Hiver, Solomani, Confederation, Ral Rankan, or Imperial fleet squatting in Leenitakot while thousands of scientists earn their pay, but instead a few hundred million, single eyed, schmoos somehow keep all the Major Races away.

Fixing Leenitakot might be something T5SS should look at. It's just as bad as all the nonsensical UWP and other stellar data that project is correcting.

 

[aramis]

I never liked that mention of an "unfinished" ringworld in Challenge magazine's Hinterworlds Sector material. It was very poorly thought out on several levels.



And that's one of the main reasons the Leenitakot ringworld idea seemingly wasn't even slightly examined before being crammed into canon. The technology required to build a ringworld - whether it's unfinished or not - is so far in advance of "everyday" technology in the OTU that Leenitakot should be a primary target of any race, state, empire, etc. with the ability to travel there.

And yet a relatively tiny Minor Race pocket empire operating at a TL C, the Outcasts of the Whispering Sky, somehow keep even the Major Races at bay and prevent any expeditions to Leenitakot.

Depending on the era, there should be a Hiver, Solomani, Confederation, Ral Rankan, or Imperial fleet squatting in Leenitakot while thousands of scientists earn their pay, but instead a few hundred million, single eyed, schmoos somehow keep all the Major Races away.

Fixing Leenitakot might be something T5SS should look at. It's just as bad as all the nonsensical UWP and other stellar data that project is correcting.

The question comes up from time to time as to how finished was Leenitakot...
Well, the Outsiders live there (as well as 6 other worlds). So at least some segments are up and running as habitat.

Also, keep in mind that if the TL is 25+, you're unlikely to access its secrets with less than TL21 tools.

A couple areas Niven didn't think through thoroughly, either... which, given the partial, can be extrapolated to have been thought out by the Kieths, is that a big open ring has far less impulse to keep moving in orbit. The ring itself is moving faster than orbital velocity, but the atmosphere wants to be at orbital velocity, and so there should be a steady wind from spin, that "accelerates" with altitude (actually, it's slower, because the people and ring are rotating faster than orbital). So apparent windspeed accelerates as altitude climbs, and spills. You either need baffles taller than atmosphere or you need gravitics or forcefields to hold in the atmosphere.

Given Traveller tech, it's likely that the ring is wider than the hab, with TL25+ solar and gravitics, and probably has an AI with self-repair and robot factories. And it's only a few percent complete, so only a few planet-equivalent cells have fully-operational biospheres.

It probably ran out of reasonably grabbable raw materials.

 

[Orr]

The question comes up from time to time as to how finished was Leenitakot...
Well, the Outsiders live there (as well as 6 other worlds). So at least some segments are up and running as habitat.

If some segments are actually habitable, there's all the more reason to investigate and/or study just how those segments are working. Right?

After all, a ringworld is far more complex than Niven first surmised. He mentions how MIT students wrote him soon after the book came out about how attitude correction thrusters would be needed and decades later a grade school class pointed out that the silt produced from normal soil erosion would have to be redistributed from the bottom of the structure's seas and oceans.

There's plenty to learn by just watching the structure work.

Also, keep in mind that if the TL is 25+, you're unlikely to access its secrets with less than TL21 tools.

Black Globes. You yourself were very active in a thread with robject and others discussing just when the Imperium found that cache of globes. They found the globes and within decades were able to not only operate them after a fashion but were also able start building their own. What other possible reverse engineering targets does Leenitakot hold?

Then there's all the "loot" that should be laying around; all those Ancient artifacts the Mongoose game hands out like DnD's magic items. Leenitakot isn't some blasted ruin from the Final War with a few undamaged objects or forgotten "vacation cottage" with a few geegaws that didn't get packed, Leenitakot is a partially working construction project roughly the size of Earth's orbit.

Also there's the construction support facilities scattered across the ringworld and through out what's left of the system. Stuff including the AI control and repair centers you mention.

It probably ran out of reasonably grabbable raw materials.

Or they ran out of time to grab/convert materials.

Speaking of conversion, wouldn't the Ancient's version of Niven's scrith be essentially priceless? You've got material strong enough to hold together a solid ring at orbital speeds, a material the Ancients were manufacturing. There have to be scrith "mills" and "stockpiles" somewhere on the ringworld or in the system, "mills" that might still be operational and "stockpiles" that can be looted.

But a bunch of TL C teletubbies are somehow keeping the Hivers, Solomani, Ral Ranta, Imperium, and everyone else away.

Sure. Whatever.

 

[rancke]

Black Globes. You yourself were very active in a thread with robject and others discussing just when the Imperium found that cache of globes. They found the globes and within decades were able to not only operate them after a fashion but were also able start building their own.

We don't know just when that stash of black globes were found, so we don't know just how many decades it took. In any case, the globes that the Imperium figured out how to build are TL15 and less effective (factor 1) than the artifact globes. I think the artifacts were TL18 (factor 4), but I could be misremembering.

Then there's all the "loot" that should be laying around; all those Ancient artifacts the Mongoose game hands out like DnD's magic items. Leenitakot isn't some blasted ruin from the Final War with a few undamaged objects or forgotten "vacation cottage" with a few geegaws that didn't get packed, Leenitakot is a partially working construction project roughly the size of Earth's orbit.

Sounds like a giant free-for-all everlasting battle in the making.


Hans

 

[robject]

So OK, good. These are problems worth thinking about, and brainstorming over (as in: brainstorms may not solve the problem(s), but they're good for simulating thought about the problem).


THE FUZZY PROBLEM: LEENITAKOT

Leenitakot has a ringworld, partially finished. I'd like Marc to keep it there, but I'd also like for it to make sense. It's obviously not really a draw, despite the fact that it probably has to have advanced technology, and despite the fact that advanced technology is always worth scientists' time studying at length under nearly any conditions.

Q1: How much attention does Leenitakot get? Why doesn't it get more/less attention?



THE FUZZY PROBLEM: TL and STELLAR-SCALE CONSTRUCTION

Assuming a standard "ringworld" is a TL27 construct, and a standard "rosette" system is a TL 24 construct, what is possible "in between" those two TLs? And what can be built at lower TLs?

Q2 * At what TL may a single world's orbit be gently nudged (e.g. up to one orbit in or out)? This may well be TL 24 (once you can nudge something 1 orbit, you can nudge it anywhere), but I'm not sure. I will assume that moving anything is going to take a long time as well as a lot of energy (F=ma).

Q3 * Where does the Stanford Torus fit in?

It SEEMS to be buildable as a TL 8 spacecraft, with a diameter ranging from 1 to 9 km. The tube diameter is likely to be 100 m to 900 m. If these assumptions are true, then I would put the volume limit on Stanford Toruses at 5 x 10^10 tons.


Q3b * Can a Stanford Torus be built that is 50 km diameter?


Q3b * At what diameter can a Torus reasonably be made open at the top?


Q4 * Where does the Bishop Ring fit?

The diameter appears to range from 10 ^2 to 10^3 km, with a width of 10 ^1 to 10^2 km, and atmosphere retention walls up to 200 km high. Assuming the smallest Bishop Ring is 1 x 10^5 m x 1 x 10^4 m x 1 x 10^5 m, volume is appx 10^12 tons: The Bishop Ring is Not A Spacecraft.

Bishop Rings look buildable at TL 9, if they truly only require carbon nanotube technology.


Q5 * Where does the Banks Orbital fit?

The diameter appears to range from 10,000 km to millions of km. So, The Banks Orbital is Not A Spacecraft, and Bigger Than A Bishop Ring.

These require better technology than carbon nanotubes; therefore, they are technologically midway between Bishop Rings and Ringworlds.



TRAVELLER RINGS, first attempt

Torus. A ring with a diameter less than ~500 km is a torus with tube diameter typically around 10% of the ring circumference.
Ring. A ring with a diameter of about 500 km and greater needs no ceiling, using 200 km high walls to hold in the atmosphere. The "floor" width is typically 1% that of the ring circumference.

TL 8: Diameter is 1 to 9 kilometers. Size 8, and in fact, a spacecraft, with upper volume as 10^10 tons. Stanford Torus.

TL 9 or higher: Diameter is 10 to 400 kilometers. Size 9, so, larger than a spacecraft. Large Stanford Torus. Probably has additional technical challenges beyond that of the smaller torus.

TL 16 or higher: Diameter is 500 to 4,000 km. Size 10 to Size 12, so, larger than a spacecraft. Bishop Ring equivalent. Assumed needs: the ability to gather up and process an entire asteroid belt; the ability to mount an efficient meteor defense for the thing, such as tractor/pressors (TL16).

TL 19 or higher: Diameter is 5 million meters to 14 million meters. Size 13 to Size ??, so, larger than a spacecraft. Banks Orbital equivalent. Assumed needs: true AI, antimatter energy (TL19), matter teleportation.

TL 27: Diameter is 15 million meters and up. Niven Ringworld. Assumed needs: scrith.



DATA POINTS

TL 9: 50 billion-ton planetoid hulls are buildable (so basically any sized starship is buildable at TL 9).

TL 24: Worlds may be placed in a rosette (so non-destructively altering orbits apparently is doable at this point).

TL 27: "Ringworlds" may be built (so, clearing out a star system with at least one GG's worth of total mass, for raw material to be shaped into a ring with a scrith-like tensile strength to allow a spin to create 1G-ish forces at planetary distances is doable at this point). Niven's Ring is (c = 1 x 10^12 m, width = 1.6 x 10^9 m, height = 1.6 x 10^6 m; vol is 2.5 x 10^27 t).

A "tiny" ringworld at Orbit 0 would have a circumference of about 1 x 10^11 m. Assuming a width of 1 x 10^8 m and a height of 5 x 10^5 m, vol would be 5 x 10^24 m^3, or 4 x 10^23 t.

 

[Orr]

We don't know just when that stash of black globes were found, so we don't know just how many decades it took. In any case, the globes that the Imperium figured out how to build are TL15 and less effective (factor 1) than the artifact globes. I think the artifacts were TL18 (factor 4), but I could be misremembering.

The time it took is irrelevant. The TL difference is irrelevant too. All that matters is that a "current day" OTU polity recovered a large cache of Ancient artifacts and not only learned how to use them but also learned how to reverse engineer them.

The fact that the Imperium struck gold once means that everyone else is going to try whether or not they'll fail 99.9999999999% of time.

Sounds like a giant free-for-all everlasting battle in the making.

Precisely.

 

[Orr]

Q1: How much attention does Leenitakot get?

Not enough.

Why doesn't it get more/less attention?

Poetic license, and anything remotely resembling plausibility be damned.

I'd like a ringworld to be somewhere in Chartered Space too. The location in Leenitakot doesn't work sadly.

In order for a ringworld not to be the site of The Neverending Battle, it either must be unknown or guarded by someone/something that prevents investigation. The first option is a nonstarter; if the ringworld is unknown than we shouldn't know about it. The second may be doable however.

We need someone strong enough to keep everyone away - A Major Race - while also somehow preventing the "guardians" from gaining any R&D benefits from the structure. IMHO, that only leaves two candidates: the K'Kree and the Zhodani.

K'Kree - The ringworld is somewhere deep in the heart of the 2,000 Worlds and the Steppelords view it with absolute religious horror. Somehow, some way, and for some reason they perceive the ringworld as an abomination. They cannot investigate it and they cannot allow anyone else to investigate it either. The system containing the ringworld doesn't appear on K'Kree maps and the systems surrounding it are completely locked down. As far as the K'Kree are concerned they are guarding the Mouth of Hell.

Zhodani - The ringworld is somewhere in the Consulate or Core Route and the Zhodani prohibit all investigation of it - even by themselves - due to precognitive and other psionic warnings. Some Zhos are precogs and the Ancient map projector occasionally provides precog visions while other warnings could be received by more mundane psionic methods. The system containing the ringworld doesn't appear on Zhodani maps and the systems surrounding it are completely locked down. As far as the Zhodani are concerned, they are preventing any investigation just as their warnings and/or glimpses of the future require them to do.

So, the ringworld is defended from wholesale investigation by someone strong enough to do so and by someone who cannot/will not investigate it themselves.

(A RPG magazine like Dragon or White Dwarf once proposed an addition to the Amber/Red Zone classification: Black Zones. A Black Zone is a system which, for various reasons, the controlling power cannot or will not admit the existence of. The ringworld system would be one of these proposed Black Zones.)

 

[whulorigan]

So OK, good. These are problems worth thinking about, and brainstorming over (as in: brainstorms may not solve the problem(s), but they're good for simulating thought about the problem).


THE FUZZY PROBLEM: LEENITAKOT

Leenitakot has a ringworld, partially finished. I'd like Marc to keep it there, but I'd also like for it to make sense. It's obviously not really a draw, despite the fact that it probably has to have advanced technology, and despite the fact that advanced technology is always worth scientists' time studying at length under nearly any conditions.


Q4 * Where does the Bishop Ring fit?

Q5 * Where does the Banks Orbital fit?

.

Is there any definitive description in canon of its size? Perhaps the term "Ringworld" can be or is being used generically in Charted Space, and can refer to any of the above structures?

In that case the problem of ringworlds and/or sphereworlds in Charted Space might be that they are not circum-stellar constructs at all, but possibly much smaller.

 

[rancke]

The time it took is irrelevant.

Then why bring it up?

The TL difference is irrelevant too.

It's very relevant to the claim that TL25+ technology would be un-reverse-engineerable. The fact that one example of TL18 technology was reverse-engineered to a TL15 version does not disprove that claim.


Hans

 

[robject]

I'd like a ringworld to be somewhere in Chartered Space too. The location in Leenitakot doesn't work sadly.

It's not a matter of me liking it or not: it's the fact of its existence at that particular location.

I suspect we can make it work in any one of several interesting ways.

Extra points for making adventure-grade rationales.

 

[robject]

It's very relevant to the claim that TL25+ technology would be un-reverse-engineerable. The fact that one example of TL18 technology was reverse-engineered to a TL15 version does not disprove that claim.

I agree with Hans. And, I believe we know that the Black Globe copies the Third Imperium produced were different in quality or capability than the TL18 originals. In other words, they're not the same, and they're not even as good.

The point is that a ringworld should be an irresistable draw, to both the scientific as well as the military communities up to several sectors away.

Who knows? Maybe this sort of trek has been going on in the research communities of so many civilizations for so many milennia, that this can take on the trappings of a pilgrimage, a crusade, a terrorist target, a Silk Road route, an atavistic-but-technic culture, and Don Quixote's quest, all in one.

 

[inexorabletash]

Possible fix: IIRC Niven's Ringworld sported very powerful defenses to thwart asteroids. We know, canonically, that these were common for even planet-bound Ancient installations, both for defense and traffic control. We also know, from canon, that it is possible for non-Ancients to gain control of them.

So the fix: the Outcasts have at least partial control of Leenitakot's defense systems. Any uninvited guests are eliminated quickly and efficiently by TL27 tech, leaving little trace behind.

That takes care of fleets. But it does not preclude the occasional stray ship that "misjumps" into the system, broadcasts GK, and oh please can it land in one of the biohabs to refuel and effect repairs? Pay no attention to the stealthed crew members slipping away...

 

[Orr]

Then why bring it up?

Why did you?

It's very relevant to the claim that TL25+ technology would be un-reverse-engineerable. The fact that one example of TL18 technology was reverse-engineered to a TL15 version does not disprove that claim.

No it isn't. Until the Imperium reverse engineered a TL18 artifact with TL15 tools and techniques, there most certainly were many people claiming it couldn't be done too.

And then they did it.

Here's the part you can't understand: Whether or not it can be done is irrelevant because people are going to try to do it anyway.

A major power or race while never to choose not to investigate Leenitakot because of the TL difference. As long as one power or race shows an interest, all the others will too. One Mopey Joe grousing that the Hivers won't gain any benefit from their investigation of Leenitakot will not keep everyone else from conducting their own investigations.

Reverse engineering isn't the only possibility at Leenitakot either. The number of working artifacts of all sizes should beggar disbelief. The ringworld isn't some blasted ruin or forgotten campsite. It's merely partially finished and there should be plenty of goodies left from when the Ancients decided to "down tools".

 

[rancke]

Why did you?

In response to your statement about the time it took.

Here's the part you can't understand: Whether or not it can be done is irrelevant because people are going to try to do it anyway.

No, I get the argument. I just think that it's flawed. An expedition to some place far away has opportunity costs for anyone who organizes it. If the respected return is too low, it won't be done. And whether or not you think you have a candle's chance in a hurricane of reverse-engineering anything you can find there is certainly going to be a factor in the decision-making.

Reverse engineering isn't the only possibility at Leenitakot either. The number of working artifacts of all sizes should beggar disbelief. The ringworld isn't some blasted ruin or forgotten campsite. It's merely partially finished and there should be plenty of goodies left from when the Ancients decided to "down tools".

That's an assumption. Not an unreasonable assumption, but not a foregone conclusion either. The project may have been terminated deliberately and anything that wasn't an integral part of the structure removed. And the thing about integral parts of TL25 structures is that they're going to stay integral parts of the structure as long as all you have to disassemble them with are TL15 tools.


Hans