TheRPGSite

Okay, The Torus isn't a Ringworld, it's a tube that forms a ring. Thus no atmosphere is lost unless the part that faces the star is pierced.

Gravitation engines make sure it stays in the correct alignment with it's star.

The days all have the same lenght, so do the nights, the light darkness cycle divides the day in perfect halves. It's created by a ring of screens that float between the star and the torus tied to the structure by electromagnetism.

The floor of the structure is perfectly opaque to all forms of radiation, the roof on the other hand lets light pass in all the spectrum while blocking all the other types of radiation.

Who built it?
Why?
Are they still around?

1. Engineering students built it.  They weren't human engineering students but the principle is basically the same.  Someone said it couldn't be done and away they went.  The post build bender hasn't ended yet.

2. A low AI nano swarm built it as a result of a coding error.  It was supposed to be a single planet but there was an unexpected recursion loop and insufficient concentrated processing power to correct it. The nano swarm was a self deconstructing one that turned into the topsoil on completion.  A low level concentration of functional nanobots maintains the torus and affects repairs.

3. A god-like alien entity that is the integrated sum of an entire society created it with the intent of creating a utopian society.  Upon completion the structure was judged non-viable for the project and abandoned without creating the intended population.  They left behind a high predation ecology with mega-fauna just to make it interesting.

Quote from: David Johansen on May 20, 2022, 11:28:08 PM
1. Engineering students built it.  They weren't human engineering students but the principle is basically the same.  Someone said it couldn't be done and away they went.  The post build bender hasn't ended yet.

2. A low AI nano swarm built it as a result of a coding error.  It was supposed to be a single planet but there was an unexpected recursion loop and insufficient concentrated processing power to correct it. The nano swarm was a self deconstructing one that turned into the topsoil on completion.  A low level concentration of functional nanobots maintains the torus and affects repairs.

3. A god-like alien entity that is the integrated sum of an entire society created it with the intent of creating a utopian society.  Upon completion the structure was judged non-viable for the project and abandoned without creating the intended population.  They left behind a high predation ecology with mega-fauna just to make it interesting.

I like number 3.

So there's no intelligent life on it?

If there is where did it come from? Different waves of colonizers from different species?

Part of the mega-fauna are giant nigh immortal worms buried so they eat the dirt from the seas and deposit their refuse on the mountain tops. Thus solving the erosion problem.

Quote from: GeekyBugle on May 20, 2022, 10:55:05 PM
Okay, The Torus isn't a Ringworld, it's a tube that forms a ring. Thus no atmosphere is lost unless the part that faces the star is pierced.

Gravitation engines make sure it stays in the correct alignment with it's star.

The days all have the same lenght, so do the nights, the light darkness cycle divides the day in perfect halves. It's created by a ring of screens that float between the star and the torus tied to the structure by electromagnetism.

The floor of the structure is perfectly opaque to all forms of radiation, the roof on the other hand lets light pass in all the spectrum while blocking all the other types of radiation.

Who built it?
Why?
Are they still around?

Reminds me of Startopia. So I will say there are maintenance bots that still work on the thing to keep stuff running.

Small change: The floating thingys for the night/day cyvle? Forget it.

The roof is made of a smart material that simulates both dawn/dusk and night by regulating the amount of light. This same material is able to change the incidence angle of the light thus simulating the seassons.

I would probably make sense if the structure was composed of individual modules, and a thread of some super-strong material that strings them together. Creating a tube with a diameter of 2 AU in one go, after all, seems prohibitively difficult. It would be easier to create independent modules, say the size of a world or a moon, then spin a giant piece of thread around the Sun, and attach them. This allows the tubeworld to grow incrementally over time, starting with just a relative handful of modules attached to a naked string, and then gradually filling out the ring. This allows older generation modules mixed with newer generation modules, and if we assume it's a polysocietal or even multi-species construct, then you can have modules in completely different styles and with different living environments.

There's also the mass problem. Creating a torus that huge might require stripping several solar systems of material. Which would be easier in the galactic core, where the stars are much closer to each other. But the core isn't friendly to a lot of life. So it might make sense to build the string in the core, and then starting traveling to more hospitable regions. How? Make the string magnetic, and use it to manipulate the Sun, turning it into a giant stellar engine. Then begin the journey toward the outer rim of the galaxy. This would take millions of years, long enough to start to fill in the torus with modules from new galactic civilizations, as the torus passes into regions they find hospitable. And why stop there? Maybe the ultimate purpose of the tour isn't just to tour the galaxy, but to escape the galaxy. This is a giant solar system-sized spaceship that's going on a billion-year journey to explore the Local Group.

Quote from: Pat on May 21, 2022, 09:14:21 AM
I would probably make sense if the structure was composed of individual modules, and a thread of some super-strong material that strings them together. Creating a tube with a diameter of 2 AU in one go, after all, seems prohibitively difficult. It would be easier to create independent modules, say the size of a world or a moon, then spin a giant piece of thread around the Sun, and attach them. This allows the tubeworld to grow incrementally over time, starting with just a relative handful of modules attached to a naked string, and then gradually filling out the ring. This allows older generation modules mixed with newer generation modules, and if we assume it's a polysocietal or even multi-species construct, then you can have modules in completely different styles and with different living environments.

The idea isn't bad, I like it, what do you mean by: "modules in completely different styles and with different living environments"?

Quote from: Pat on May 21, 2022, 09:37:10 AM
There's also the mass problem. Creating a torus that huge might require stripping several solar systems of material. Which would be easier in the galactic core, where the stars are much closer to each other. But the core isn't friendly to a lot of life. So it might make sense to build the string in the core, and then starting traveling to more hospitable regions. How? Make the string magnetic, and use it to manipulate the Sun, turning it into a giant stellar engine. Then begin the journey toward the outer rim of the galaxy. This would take millions of years, long enough to start to fill in the torus with modules from new galactic civilizations, as the torus passes into regions they find hospitable. And why stop there? Maybe the ultimate purpose of the tour isn't just to tour the galaxy, but to escape the galaxy. This is a giant solar system-sized spaceship that's going on a billion-year journey to explore the Local Group.

Yes! I had thought about turning it's star into an engine this morning while walking the dog. And if it's an engine it also is a weapon.

The mass problem is an interesting one, especially since the material needs to be nigh indestructible, maybe they were in a pit stop to find more resources when something happened and the construct remained parked there. It's a solar system with no inner planets but it has the giant exterior planets.

Maybe they used to stop and strip mine solar systems including their stars?

But the tripulation died for some unknown cause and the construct is still parked there.

Quote from: GeekyBugle on May 21, 2022, 11:22:39 AM

Quote from: Pat on May 21, 2022, 09:14:21 AM
I would probably make sense if the structure was composed of individual modules, and a thread of some super-strong material that strings them together. Creating a tube with a diameter of 2 AU in one go, after all, seems prohibitively difficult. It would be easier to create independent modules, say the size of a world or a moon, then spin a giant piece of thread around the Sun, and attach them. This allows the tubeworld to grow incrementally over time, starting with just a relative handful of modules attached to a naked string, and then gradually filling out the ring. This allows older generation modules mixed with newer generation modules, and if we assume it's a polysocietal or even multi-species construct, then you can have modules in completely different styles and with different living environments.

The idea isn't bad, I like it, what do you mean by: "modules in completely different styles and with different living environments"?

One way to think of it as a train with no end. The modules would be the cars, though of course the cars might be the size of worlds. There could be ancient modules, and newer ones in newer styles and based on newer technologies. The disparity could be immense, since we're potentially talking about deep time, not just a few years, centuries, or even millennia. Then consider modules added by different civilizations. They might have very different needs and styles. Or species -- there could be water modules, or near-vacuums, and so on. Some modules might have shared environments with their neighbors, with the "doors" between the modules open.

Others might be closed, because of incompatible environments, or worries of ecological contamination. It would still make sense to have a standard common ground, so travelers could pass down the torus, but the common ground is most likely a contained vacuum. Say a torus within a torus, an internal tube with no impeding air. That would allow transit using mono-ships, that are propelled magnetically or gravitically, and which could use gravity differentials or centrifugal force to reach ridiculous speeds, like particles in a collider.

Incidentally, you don't have to "park" it anywhere. Since a stellar engine is based on sublight travel, perhaps very slow sublight travel with transit times in the millions of years, it could be on its way to its next stop and still approachable or visitable. Not dissimilar to the Puppeteer's Fleet of Worlds, except much grander in scope.

Quote from: Pat on May 21, 2022, 01:14:05 PM

Quote from: GeekyBugle on May 21, 2022, 11:22:39 AM

Quote from: Pat on May 21, 2022, 09:14:21 AM
I would probably make sense if the structure was composed of individual modules, and a thread of some super-strong material that strings them together. Creating a tube with a diameter of 2 AU in one go, after all, seems prohibitively difficult. It would be easier to create independent modules, say the size of a world or a moon, then spin a giant piece of thread around the Sun, and attach them. This allows the tubeworld to grow incrementally over time, starting with just a relative handful of modules attached to a naked string, and then gradually filling out the ring. This allows older generation modules mixed with newer generation modules, and if we assume it's a polysocietal or even multi-species construct, then you can have modules in completely different styles and with different living environments.

The idea isn't bad, I like it, what do you mean by: "modules in completely different styles and with different living environments"?

One way to think of it as a train with no end. The modules would be the cars, though of course the cars might be the size of worlds. There could be ancient modules, and newer ones in newer styles and based on newer technologies. The disparity could be immense, since we're potentially talking about deep time, not just a few years, centuries, or even millennia. Then consider modules added by different civilizations. They might have very different needs and styles. Or species -- there could be water modules, or near-vacuums, and so on. Some modules might have shared environments with their neighbors, with the "doors" between the modules open.

Others might be closed, because of incompatible environments, or worries of ecological contamination. It would still make sense to have a standard common ground, so travelers could pass down the torus, but the common ground is most likely a contained vacuum. Say a torus within a torus, an internal tube with no impeding air. That would allow transit using mono-ships, that are propelled magnetically or gravitically, and which could use gravity differentials or centrifugal force to reach ridiculous speeds, like particles in a collider.

Incidentally, you don't have to "park" it anywhere. Since a stellar engine is based on sublight travel, perhaps very slow sublight travel with transit times in the millions of years, it could be on its way to its next stop and still approachable or visitable. Not dissimilar to the Puppeteer's Fleet of Worlds, except much grander in scope.

Okay, now I grok it.

You're thinking more of a ship/space station than an artificial world, what would the collector build if he was into preserving whole worlds? something like you postulate with closed modules. I was thinking more of a unique world. So the "Natives" (in the case of the tripulation all dying out) have forgotten they live in an artificial construct. But since it's so big you could have both at the same time, just imagine 13 million earths unfolded and sewn together, I reccon there's more than enough room for both being true.

Maybe it's a space ark? The builders are escaping the galaxy and saving/kidnapping whole worlds (the living things) into their ship.

Quote from: GeekyBugle on May 21, 2022, 01:33:55 PM

You're thinking more of a ship/space station than an artificial world, what would the collector build if he was into preserving whole worlds? something like you postulate with closed modules.

I think it's both, and there's no escaping that. But if you're referencing Ringworld, remember the inset world maps? The modules themselves could be titanic, with many times the surface area and volume of Earth. That's one of the biggest things to struggle with when thinking about a construct like this: The sheer scale. The Ringworld alone has more space than 3 million Earths. There can be more livable space in a single torus than in the entire rest of the galaxy.

And if you want to think even bigger, what if the first torus is filled? What's stopping them from adding more toruses, in different orbits? One of the views of a Dyson sphere is overlapping spaghetti circling the Sun. You could have many toruses, a partial step towards a Dyson sphere.

Quote from: Pat on May 21, 2022, 01:39:59 PM

Quote from: GeekyBugle on May 21, 2022, 01:33:55 PM

You're thinking more of a ship/space station than an artificial world, what would the collector build if he was into preserving whole worlds? something like you postulate with closed modules.

I think it's both, and there's no escaping that. But if you're referencing Ringworld, remember the inset world maps? The modules themselves could be titanic, with many times the surface area and volume of Earth. That's one of the biggest things to struggle with when thinking about a construct like this: The sheer scale. The Ringworld alone has more space than 3 million Earths. There can be more livable space in a single torus than in the entire rest of the galaxy.

And if you want to think even bigger, what if the first torus is filled? What's stopping them from adding more toruses, in different orbits? One of the views of a Dyson sphere is overlapping spaghetti circling the Sun. You could have many toruses, a partial step towards a Dyson sphere.

Yeah, but the maps all shared the same atmosphere, if I got it right you want even different atmospheres.

As for other Torus, who's to say they don't exist? build one (or start building it in your version) an use the star from another system and send it in a slightly different direction, you divy up the population in half and now it's harder they ever go extinct.

Quote from: GeekyBugle on May 21, 2022, 01:51:39 PM
Yeah, but the maps all shared the same atmosphere, if I got it right you want even different atmospheres.

My point is the torus is so huge, that all those maps could be contained in the same module. From the perspective of a space traveler approaching the torus, they might see it as a string of modules, some independent, others with the doors open so they share atmospheres/ecologies/water systems. But from the perspective of someone living in the torus, a single module might be a whole world greater than the one we live on. Someone could walk for their entire life, and never even reach one end of their module, much less a series of open modules. The trick from a setting standpoint would be to figure out ways to help the players grasp that sense of scale, and to shift between different perspectives.

Quote from: GeekyBugle on May 20, 2022, 10:55:05 PMThe days all have the same lenght, so do the nights, the light darkness cycle divides the day in perfect halves.

Is there any reason you actually need a day/night cycle? Also, how does gravity work?

Quote from: hedgehobbit on May 21, 2022, 09:59:13 PM

Quote from: GeekyBugle on May 20, 2022, 10:55:05 PMThe days all have the same lenght, so do the nights, the light darkness cycle divides the day in perfect halves.

Is there any reason you actually need a day/night cycle? Also, how does gravity work?

I mean, this is an open content collaborative effort, if YOU want your totally not Ringworld not to have a day/night cycle by all means.

Gravity, well, for starters the mass of the construct, but also if you noticed I wrote something about gravity drives/engines to keep the construct in a concentric orbit with it's star. So, the presumption is that if the construc doesn't have enough mass and the centrifugal force isn't enough well the builders had the tech to create artifical gravity.

Quote from: Pat on May 21, 2022, 04:06:26 PM

Quote from: GeekyBugle on May 21, 2022, 01:51:39 PM
Yeah, but the maps all shared the same atmosphere, if I got it right you want even different atmospheres.

My point is the torus is so huge, that all those maps could be contained in the same module. From the perspective of a space traveler approaching the torus, they might see it as a string of modules, some independent, others with the doors open so they share atmospheres/ecologies/water systems. But from the perspective of someone living in the torus, a single module might be a whole world greater than the one we live on. Someone could walk for their entire life, and never even reach one end of their module, much less a series of open modules. The trick from a setting standpoint would be to figure out ways to help the players grasp that sense of scale, and to shift between different perspectives.

Right, so, 13 million earths give or take a few, to keep the math simple lets say each module is what? 100 earths?

I do love your idea, it allows for an almost infinite number of "worlds" within the construct. Heck you could even have some totally aquatic as long as you keep the mass distributed in such a way it doesn't throw the construct's orbit out of wak.

Is the torus rotating? I think that it would in order to be in orbit around its sun. That means a speed of 770 million miles per hour. How do you dock with it?

If the torus is spinning in orbit around the sun, then it is creating centrifugal force and artificial gravity. How do they keep the inner edge of the torus (the ceiling) from collapsing in on the surface of the torus?

Is the torus and star travelling through space? if it travels at any appreciable fraction of light, there will be complications. What does it use as a  meteor defense? How do they block the increased radiation from moving through interstellar space?

Quote from: jeff37923 on May 22, 2022, 10:46:43 AM
Is the torus rotating? I think that it would in order to be in orbit around its sun. That means a speed of 770 million miles per hour. How do you dock with it?

If the torus is spinning in orbit around the sun, then it is creating centrifugal force and artificial gravity. How do they keep the inner edge of the torus (the ceiling) from collapsing in on the surface of the torus?

Is the torus and star travelling through space? if it travels at any appreciable fraction of light, there will be complications. What does it use as a  meteor defense? How do they block the increased radiation from moving through interstellar space?

1.- By equating your speed with it.

2.- The material is nigh indestructible. The material for the top is the same that for the bottom.

3.- It's why I wanted it parked in a planetary system where all of the inner planets have been removed and only the external giants remain. Assuming a species able to build it means they could even move some other giant planet from elsewhere to orbit the Torus' star.

Reject Science, embrace handwavium.

Edited to add: The earth's speed around the sun is about 67,000 miles per hour not 770 million miles per hour. For those who need science in their science fiction.

Source: https://www.scientificamerican.com/article/how-fast-is-the-earth-mov/ (https://www.scientificamerican.com/article/how-fast-is-the-earth-mov/)

If someone wants to do the math to determine the radius of the torus here's the formula. https://socratic.org/questions/how-fast-would-something-have-rotate-in-order-to-create-earth-like-gravity-from- (https://socratic.org/questions/how-fast-would-something-have-rotate-in-order-to-create-earth-like-gravity-from-)

Quote from: GeekyBugle on May 22, 2022, 11:23:40 AM

Reject Science, embrace handwavium.

Then don't call it science fiction. Call it science fantasy.

Or call it what it is, a piss-poor Ringworld rip-off.

Quote from: GeekyBugle on May 22, 2022, 11:32:28 AM
If someone wants to do the math to determine the radius of the torus here's the formula. https://socratic.org/questions/how-fast-would-something-have-rotate-in-order-to-create-earth-like-gravity-from- (https://socratic.org/questions/how-fast-would-something-have-rotate-in-order-to-create-earth-like-gravity-from-)

So which is it?

Quote from: GeekyBugle on May 22, 2022, 11:23:40 AM

Reject Science, embrace handwavium.

Quote from: jeff37923 on May 22, 2022, 01:40:27 PM

Quote from: GeekyBugle on May 22, 2022, 11:23:40 AM

Reject Science, embrace handwavium.

Then don't call it science fiction. Call it science fantasy.

Or call it what it is, a piss-poor Ringworld rip-off.

So you didn't read the title of the thread.

And like you always do you'll start a fight to disguise your own stupidity. Tired of your BS dude, welcome to the ignore list.

Quote from: jeff37923 on May 22, 2022, 01:40:58 PM

Quote from: GeekyBugle on May 22, 2022, 11:32:28 AM
If someone wants to do the math to determine the radius of the torus here's the formula. https://socratic.org/questions/how-fast-would-something-have-rotate-in-order-to-create-earth-like-gravity-from- (https://socratic.org/questions/how-fast-would-something-have-rotate-in-order-to-create-earth-like-gravity-from-)

So which is it?

Quote from: GeekyBugle on May 22, 2022, 11:23:40 AM

Reject Science, embrace handwavium.

Which is what? Do you see a contradiction on me saying I don't care about the science and providing a link for ohers that might care about it to get the math?

I'll tell you what it is... It's go fuck yourself.

Quote from: jeff37923 on May 22, 2022, 10:46:43 AM
Is the torus rotating? I think that it would in order to be in orbit around its sun. That means a speed of 770 million miles per hour. How do you dock with it?

That's 1.148 times the speed of light.

Who exactly is using handwavium and science fantasy?

Quote from: GeekyBugle on May 22, 2022, 09:27:05 AMI mean, this is an open content collaborative effort, if YOU want your totally not Ringworld not to have a day/night cycle by all means.

My question wasn't clear. I meant what is the game benefit to having this thing have a day/night cycle. If you are trying to replicate an earth-like habitat, a bigger downside would be the fact that the sun is always directly above you.

A normal tree or bush grows in a spherical shape, so as the sun moves across the sky, the cross section of the sun hitting the tree will be constant (ish). But if the sun is always directly above, the solar energy received will be a downward cross section only. So trees that are tall and thin, like pines or spruce will be at a huge disadvantage compared to a tree that is flat and broad. This will have a big impact on how vegetation grows.

Similarly, if you make the night by blocking the sun, then the night sky would be completely black.

Quote from: jeff37923 on May 22, 2022, 10:46:43 AMIf the torus is spinning in orbit around the sun, then it is creating centrifugal force and artificial gravity. How do they keep the inner edge of the torus (the ceiling) from collapsing in on the surface of the torus?

Because the tube is full of air, it will be like a huge balloon, so more likely to pop than crush. The bigger issue with spinning it up for gravity is that this will act as a force trying to expand the radius and pull itself apart. Plus if one part does break, the thing will rip apart as the sections fly to a higher orbit.

If it was just rotating at a normal orbit, not only would the thing be more stable, but if a section did break apart, the rest of it would still orbit normally. And it would be easier to dock with. Of course, this requires artificial gravity but that's probably something you'd need anyway since the gravity produced by the mass of the land would be from the center of mass and, thus, not directly perpendicular to the surface.

Quote from: hedgehobbit on May 22, 2022, 02:57:09 PM

Quote from: GeekyBugle on May 22, 2022, 09:27:05 AMI mean, this is an open content collaborative effort, if YOU want your totally not Ringworld not to have a day/night cycle by all means.

My question wasn't clear. I meant what is the game benefit to having this thing have a day/night cycle. If you are trying to replicate an earth-like habitat, a bigger downside would be the fact that the sun is always directly above you.

A normal tree or bush grows in a spherical shape, so as the sun moves across the sky, the cross section of the sun hitting the tree will be constant (ish). But if the sun is always directly above, the solar energy received will be a downward cross section only. So trees that are tall and thin, like pines or spruce will have significantly less cross section than a tree that is flat and broad. This will have a big impact on how vegetation grows.

Similarly, if you make the night by blocking the sun, then the night sky would be completely black.

Quote from: GeekyBugle on May 21, 2022, 02:04:29 AM
Small change: The floating thingys for the night/day cyvle? Forget it.

The roof is made of a smart material that simulates both dawn/dusk and night by regulating the amount of light. This same material is able to change the incidence angle of the light thus simulating the seassons.

So, if it can simulate seasons why wouldn't it be able to simulate the sun's movement by changing the angle of the light?

Here's the thing, we currently have materials that can block from 0% to 100% of the sun light.

So, the roof doesn't block 100% just enough to have a night and whatever it lets pass is difused to simulate a moonlit night.

Quote from: Pat on May 22, 2022, 02:22:07 PM

Quote from: jeff37923 on May 22, 2022, 10:46:43 AM
Is the torus rotating? I think that it would in order to be in orbit around its sun. That means a speed of 770 million miles per hour. How do you dock with it?

That's 1.148 times the speed of light.

Who exactly is using handwavium and science fantasy?

My bad. I misremembered the numbers. Mea culpa.

Quote from: GeekyBugle on May 22, 2022, 01:56:45 PM

Quote from: jeff37923 on May 22, 2022, 01:40:27 PM

Quote from: GeekyBugle on May 22, 2022, 11:23:40 AM

Reject Science, embrace handwavium.

Then don't call it science fiction. Call it science fantasy.

Or call it what it is, a piss-poor Ringworld rip-off.

So you didn't read the title of the thread.

And like you always do you'll start a fight to disguise your own stupidity. Tired of your BS dude, welcome to the ignore list.

No, I read the title of the thread and since the idea has been done before (a lot!) making the Ringworld a torus isn't that big a stretch to make it unique. Here, I'll give you a hint. Go read Bigger Than Worlds by Larry Niven and get back to me.

Quote from: GeekyBugle on May 22, 2022, 01:58:32 PM

Quote from: jeff37923 on May 22, 2022, 01:40:58 PM

Quote from: GeekyBugle on May 22, 2022, 11:32:28 AM
If someone wants to do the math to determine the radius of the torus here's the formula. https://socratic.org/questions/how-fast-would-something-have-rotate-in-order-to-create-earth-like-gravity-from- (https://socratic.org/questions/how-fast-would-something-have-rotate-in-order-to-create-earth-like-gravity-from-)

So which is it?

Quote from: GeekyBugle on May 22, 2022, 11:23:40 AM

Reject Science, embrace handwavium.

Which is what? Do you see a contradiction on me saying I don't care about the science and providing a link for ohers that might care about it to get the math?

I'll tell you what it is... It's go fuck yourself.

And here I thought you had me on your Ignore List.

So why a torus? A spinning ring with sufficiently high walls won't lose much atmosphere, so why bother with a top?

I can think of a couple possibilities. The first is that the torus might be much smaller on scale than the Ringworld. It would still be immensely huge, because we're still talking about a structure that circles a Sun. But it wouldn't be as wide. The torus might only be a couple hundred meters in diameter, or a couple hundred km, or even a couple hundred thousand km. Yes, even the last is small compared to Niven's Ringworld, which is 1.6 million kilometers across (and 1,600 km high). Working out the math, a 300 m wide torus would have the surface area (on the bottom half of the torus) of about 0.90 Earths. A 300 km torus would be equivalent to about 900 Earths, and a 300,000 km torus would be equivalent to 900,000 Earths (approaching but not equaling the Ringworld's 3 million Earths).

If we assume the torus spins for gravity, this would create an interesting geography. The bottom of the torus would be relatively flat, and where all the water collects. There might be a massive ocean-river running down the center, and massive water redistribution systems would probably be needed. But as you go up the sides, the ascent would become steeper and steeper, effectively turning into mountains or cliffs. A lot of people would have to learn to live vertically. Think terraced farms and cliff-cities. If large enough, the upper section of the torus would have very thin air. It would be a good place for a mass transit rail or tube system (or systems), as well as high-speed flights.

Another alternative is the torus is full. This could be water, creating a vast Sun-encircling ocean. Or it could be air. In the latter case, it would make most sense to lower the spin, and effectively make the torus a microgravity environment of flying creatures. In that case, you could easily steal from another of Niven's works, which is explicitly set in a Sun-encircling torus: The Integral Trees and The Smoke Ring.

What's the biggest problem with a giant tube? Punctures. You need a system to deal with them. Ships are traditionally designed with bulkheads, which allow parts of the vessel to be sealed from the rest of the vessel, preventing catastrophic flooding from a minor hole. Another solution sometimes used in things like gas tanks is sponges that keep the liquid from draining out quickly. Or think human circulatory systems, where blood clots on exposure to air. The module system is one possibility, and you could come up with variants like giant bubbles that connect and interconnect and slide across each other, but stick to each other. giant tube around the sun might filled with a foam- or sponge-like material, that creates pockets or bubbles, and vast networks of paths or tunnels from one pocket to the next. Massive differentials in pressure would cause them to collapse, sealing off damaged areas. Or the materials used to design the tube might be reactive, and quickly form or grow patches when a puncture occurs. There might be giant protrusions or plasts, where ancient damage was repaired.

Quote from: Pat on May 22, 2022, 05:53:25 PM
So why a torus? A spinning ring with sufficiently high walls won't lose much atmosphere, so why bother with a top?

I can think of a couple possibilities. The first is that the torus might be much smaller on scale than the Ringworld. It would still be immensely huge, because we're still talking about a structure that circles a Sun. But it wouldn't be as wide. The torus might only be a couple hundred meters in diameter, or a couple hundred km, or even a couple hundred thousand km. Yes, even the last is small compared to Niven's Ringworld, which is 1.6 million kilometers across (and 1,600 km high). Working out the math, a 300 m wide torus would have the surface area (on the bottom half of the torus) of about 0.90 Earths. A 300 km torus would be equivalent to about 900 Earths, and a 300,000 km torus would be equivalent to 900,000 Earths (approaching but not equaling the Ringworld's 3 million Earths).

If we assume the torus spins for gravity, this would create an interesting geography. The bottom of the torus would be relatively flat, and where all the water collects. There might be a massive ocean-river running down the center, and massive water redistribution systems would probably be needed. But as you go up the sides, the ascent would become steeper and steeper, effectively turning into mountains or cliffs. A lot of people would have to learn to live vertically. Think terraced farms and cliff-cities. If large enough, the upper section of the torus would have very thin air. It would be a good place for a mass transit rail or tube system (or systems), as well as high-speed flights.

Another alternative is the torus is full. This could be water, creating a vast Sun-encircling ocean. Or it could be air. In the latter case, it would make most sense to lower the spin, and effectively make the torus a microgravity environment of flying creatures. In that case, you could easily steal from another of Niven's works, which is explicitly set in a Sun-encircling torus: The Integral Trees and The Smoke Ring.

What's the biggest problem with a giant tube? Punctures. You need a system to deal with them. Ships are traditionally designed with bulkheads, which allow parts of the vessel to be sealed from the rest of the vessel, preventing catastrophic flooding from a minor hole. Another solution sometimes used in things like gas tanks is sponges that keep the liquid from draining out quickly. Or think human circulatory systems, where blood clots on exposure to air. The module system is one possibility, and you could come up with variants like giant bubbles that connect and interconnect and slide across each other, but stick to each other. giant tube around the sun might filled with a foam- or sponge-like material, that creates pockets or bubbles, and vast networks of paths or tunnels from one pocket to the next. Massive differentials in pressure would cause them to collapse, sealing off damaged areas. Or the materials used to design the tube might be reactive, and quickly form or grow patches when a puncture occurs. There might be giant protrusions or plasts, where ancient damage was repaired.

Because The Torus ISN'T a ring, thus it's not the Ringworld.

The size of the thing is determined by the distance it needs to be from it's star to be habitable, what it's called the goldylocks zone, so it needs to be at about the same distance from a sun like star as earth is from it's star.

Make it too narrow and you loose the sense of infinity.

Quote from: GeekyBugle on May 23, 2022, 02:37:28 PM

Because The Torus ISN'T a ring, thus it's not the Ringworld.

If it quacks like a duck.....

Quote from: GeekyBugle on May 23, 2022, 02:37:28 PM

Because The Torus ISN'T a ring, thus it's not the Ringworld.

That's a design choice, to differentiate it from a similar concept. It's still useful to have an in-setting rationale for why they chose a tube over a band, and to explore how they'll differ.

Quote from: GeekyBugle on May 23, 2022, 02:37:28 PM
The size of the thing is determined by the distance it needs to be from it's star to be habitable, what it's called the goldylocks zone, so it needs to be at about the same distance from a sun like star as earth is from it's star.

All my calculations used the same diameter, i.e. the Ringworld's.

Though thinking about it, you're assuming the torus is made of a material that can selectively allow only some of the electromagnetic radiation from the sun to pass through. If that's true (and sufficiently efficient), you're not restricted to the goldilocks zone anymore. You could give it the diameter of Mercury's orbit, and just give the sky the equivalent of shades. That's one difference from an open-topped Ringworld.

Quote from: GeekyBugle on May 23, 2022, 02:37:28 PM
Make it too narrow and you loose the sense of infinity.

Loops never end, so by definition it's infinite. And it's a loop 2 AU across, so it'll always feel infinite. If you walk 30 miles a day every day for your entire life, from age 15 to age 70, then you'll still only make it 1/1,000th the way around. How far you can walk sideways isn't essential to the sense of scale.

Quote from: Pat on May 23, 2022, 03:14:31 PM

Quote from: GeekyBugle on May 23, 2022, 02:37:28 PM

Because The Torus ISN'T a ring, thus it's not the Ringworld.

That's a design choice, to differentiate it from a similar concept. It's still useful to have an in-setting rationale for why they chose a tube over a band, and to explore how they'll differ.

Quote from: GeekyBugle on May 23, 2022, 02:37:28 PM
The size of the thing is determined by the distance it needs to be from it's star to be habitable, what it's called the goldylocks zone, so it needs to be at about the same distance from a sun like star as earth is from it's star.

All my calculations used the same diameter, i.e. the Ringworld's.

Though thinking about it, you're assuming the torus is made of a material that can selectively allow only some of the electromagnetic radiation from the sun to pass through. If that's true (and sufficiently efficient), you're not restricted to the goldilocks zone anymore. You could give it the diameter of Mercury's orbit, and just give the sky the equivalent of shades. That's one difference from an open-topped Ringworld.

Quote from: GeekyBugle on May 23, 2022, 02:37:28 PM
Make it too narrow and you loose the sense of infinity.

Loops never end, so by definition it's infinite. And it's a loop 2 AU across, so it'll always feel infinite. If you walk 30 miles a day every day for your entire life, from age 15 to age 70, then you'll still only make it 1/1,000th the way around. How far you can walk sideways isn't essential to the sense of scale.

In the orbit of mercury and then you have no photosyntesis because you lack enough light.

Plus, lets say the thing is perfectly impervious to that kind of heat... How do you get in and out? All the ships need to be perfectly impervious to the heat too.

No, I think that given a sun like star at the very least it would need to be in Venus' orbit.

Yes, why did they choose a torus and not a ring, that's a kind of important question I hadn't thought about.

Quote from: GeekyBugle on May 23, 2022, 03:23:09 PM
In the orbit of mercury and then you have no photosyntesis because you lack enough light.

Are you confusing Mercury with one of the outer planets?

Quote from: Pat on May 23, 2022, 03:29:18 PM

Quote from: GeekyBugle on May 23, 2022, 03:23:09 PM
In the orbit of mercury and then you have no photosyntesis because you lack enough light.

Are you confusing Mercury with one of the outer planets?

No, you need to block it to not get cooked/blinded. Light carries heat too.

Quote from: GeekyBugle on May 23, 2022, 03:56:31 PM

Quote from: Pat on May 23, 2022, 03:29:18 PM

Quote from: GeekyBugle on May 23, 2022, 03:23:09 PM
In the orbit of mercury and then you have no photosyntesis because you lack enough light.

Are you confusing Mercury with one of the outer planets?

No, you need to block it to not get cooked/blinded. Light carries heat too.

Isn't that (radiant heat) pretty much the only way a star gives off heat? I suppose mass elections can give off heat too, but I'd imagine it's tiny in comparison (unless you're unfortunate enough to get hit by one).

Interesting concept, but if this thing is entirely self-contained, why does it even need to circle a star? From the descriptions it seems to be entirely sealed all around with all the stuff it needs to sustain life contained within. Wouldn't that just be like a gigantic donut shaped generation ship at that point?

Even if it were to still circle a star, this thing would need to be so huge as to beg credulity. And from a gameplay point of view PCs would still be confined to just one portion of the thing, perhaps one or two modules (maybe a handful) if going with Pat's module-based architecture,, since it would be so huge no one will even live long enough to ever explore it completely, even at a cursory level. How do you even map this thing?

Quote from: VisionStorm on May 23, 2022, 04:40:03 PM
Interesting concept, but if this thing is entirely self-contained, why does it even need to circle a star? From the descriptions it seems to be entirely sealed all around with all the stuff it needs to sustain life contained within. Wouldn't that just be like a gigantic donut shaped generation ship at that point?

Even if it were to still circle a star, this thing would need to be so huge as to beg credulity. And from a gameplay point of view PCs would still be confined to just one portion of the thing, perhaps one or two modules (maybe a handful) if going with Pat's module-based architecture,, since it would be so huge no one will even live long enough to ever explore it completely, even at a cursory level. How do you even map this thing?

The star provides light, heat and energy.

13 million earths approx.

You don't map it, you map at best one module if going with Pat's idea, the rest it's up for the GM to flesh out if he wants to.

Here's an interesting twist that's possible with a torus, but not a band.

Ringworld has gravity because it's in orbit around the Sun. That means you can only use one side of the band, and need to match velocities to visit the Ringworld.

But with a torus, you don't need to spin the big hoop for gravity. Instead, you could twist it. This works best if it's designed in a modular form, with different roughly cylindrical modules connected end to end in a long Sun-circling chain. That way, you can spin each of the modules independently, giving them each a different gravity. Since you're spinning cylinders around their axis, the axis would a zero-G or microgravity zone, and it would be the natural transition point where you can pass from one module to the next. Visiting the torus would be much easier, since the orbital velocity can be lower (you'd still need some spin).

Quote from: Pat on May 23, 2022, 06:55:26 PM
Here's an interesting twist that's possible with a torus, but not a band.

Ringworld has gravity because it's in orbit around the Sun. That means you can only use one side of the band, and need to match velocities to visit the Ringworld.

But with a torus, you don't need to spin the big hoop for gravity. Instead, you could twist it. This works best if it's designed in a modular form, with different roughly cylindrical modules connected end to end in a long Sun-circling chain. That way, you can spin each of the modules independently, giving them each a different gravity. Since you're spinning cylinders around their axis, the axis would a zero-G or microgravity zone, and it would be the natural transition point where you can pass from one module to the next. Visiting the torus would be much easier, since the orbital velocity can be lower (you'd still need some spin).

I like it but it has a fatal flaw: It can't work mechanically, you can't have the modules interconected and spining on their axis. You would need a space between cylinders and maybe conect them by a relatively thin point in their axis.

But it would also create a day/night cycle.

Quote from: GeekyBugle on May 23, 2022, 10:30:49 PM

Quote from: Pat on May 23, 2022, 06:55:26 PM
Here's an interesting twist that's possible with a torus, but not a band.

Ringworld has gravity because it's in orbit around the Sun. That means you can only use one side of the band, and need to match velocities to visit the Ringworld.

But with a torus, you don't need to spin the big hoop for gravity. Instead, you could twist it. This works best if it's designed in a modular form, with different roughly cylindrical modules connected end to end in a long Sun-circling chain. That way, you can spin each of the modules independently, giving them each a different gravity. Since you're spinning cylinders around their axis, the axis would a zero-G or microgravity zone, and it would be the natural transition point where you can pass from one module to the next. Visiting the torus would be much easier, since the orbital velocity can be lower (you'd still need some spin).

I like it but it has a fatal flaw: It can't work mechanically, you can't have the modules interconected and spining on their axis. You would need a space between cylinders and maybe conect them by a relatively thin point in their axis.

But it would also create a day/night cycle.

You're talking about unobtainum materials and gravity control anyway, so creating the equivalent of frictionless bearings/locks in zero-G isn't much of a stretch.

Quote from: Pat on May 23, 2022, 10:38:59 PM

Quote from: GeekyBugle on May 23, 2022, 10:30:49 PM

Quote from: Pat on May 23, 2022, 06:55:26 PM
Here's an interesting twist that's possible with a torus, but not a band.

Ringworld has gravity because it's in orbit around the Sun. That means you can only use one side of the band, and need to match velocities to visit the Ringworld.

But with a torus, you don't need to spin the big hoop for gravity. Instead, you could twist it. This works best if it's designed in a modular form, with different roughly cylindrical modules connected end to end in a long Sun-circling chain. That way, you can spin each of the modules independently, giving them each a different gravity. Since you're spinning cylinders around their axis, the axis would a zero-G or microgravity zone, and it would be the natural transition point where you can pass from one module to the next. Visiting the torus would be much easier, since the orbital velocity can be lower (you'd still need some spin).

I like it but it has a fatal flaw: It can't work mechanically, you can't have the modules interconected and spining on their axis. You would need a space between cylinders and maybe conect them by a relatively thin point in their axis.

But it would also create a day/night cycle.

You're talking about unobtainum materials and gravity control anyway, so creating the equivalent of frictionless bearings/locks in zero-G isn't much of a stretch.

Oh, it's not the friction I'm "objecting" to, it's just that it wouldn't look as a continual tube from "close" distance.

Each section would need to be a perfect cylinder, which means you'd need a space between each, bigger on the side of the torus fartest from the star.

In exchange it solves the night and day cycle in a perfect fashion.

It also means no inner hyperloop connecting different modules.

Quote from: HappyDaze on May 23, 2022, 04:08:33 PM

Quote from: GeekyBugle on May 23, 2022, 03:56:31 PM

Quote from: Pat on May 23, 2022, 03:29:18 PM

Quote from: GeekyBugle on May 23, 2022, 03:23:09 PM
In the orbit of mercury and then you have no photosyntesis because you lack enough light.

Are you confusing Mercury with one of the outer planets?

No, you need to block it to not get cooked/blinded. Light carries heat too.

Isn't that (radiant heat) pretty much the only way a star gives off heat? I suppose mass elections can give off heat too, but I'd imagine it's tiny in comparison (unless you're unfortunate enough to get hit by one).

I'm going to assume you're not talking about elections nor erections, so it leaves what? ejections? As in solar flares? yeah that's the other way a star gives off heat. I mean if it hits you you get engulfed by a flame at 10's of millions of kelvins.

This reminds me not only of Ringworld, but also the Cageworld series by Colin Kapp (https://en.wikipedia.org/wiki/Cageworld_series)

Quote from: GeekyBugle on May 24, 2022, 01:51:02 AM

Quote from: Pat on May 23, 2022, 10:38:59 PM

Quote from: GeekyBugle on May 23, 2022, 10:30:49 PM

Quote from: Pat on May 23, 2022, 06:55:26 PM
Here's an interesting twist that's possible with a torus, but not a band.

Ringworld has gravity because it's in orbit around the Sun. That means you can only use one side of the band, and need to match velocities to visit the Ringworld.

But with a torus, you don't need to spin the big hoop for gravity. Instead, you could twist it. This works best if it's designed in a modular form, with different roughly cylindrical modules connected end to end in a long Sun-circling chain. That way, you can spin each of the modules independently, giving them each a different gravity. Since you're spinning cylinders around their axis, the axis would a zero-G or microgravity zone, and it would be the natural transition point where you can pass from one module to the next. Visiting the torus would be much easier, since the orbital velocity can be lower (you'd still need some spin).

I like it but it has a fatal flaw: It can't work mechanically, you can't have the modules interconected and spining on their axis. You would need a space between cylinders and maybe conect them by a relatively thin point in their axis.

But it would also create a day/night cycle.

You're talking about unobtainum materials and gravity control anyway, so creating the equivalent of frictionless bearings/locks in zero-G isn't much of a stretch.

Oh, it's not the friction I'm "objecting" to, it's just that it wouldn't look as a continual tube from "close" distance.

Each section would need to be a perfect cylinder, which means you'd need a space between each, bigger on the side of the torus fartest from the star.

In exchange it solves the night and day cycle in a perfect fashion.

It also means no inner hyperloop connecting different modules.

Gotcha, but assuming my math is correct, the difference is trivial. The Ringworld has a circumference of 970,000,000 km. If we use that as the inner circumference of the torus and assume each module is 1 km wide, then the outer circumference becomes 970,000,006.283 km. If each cylinder is 10 km long, that means the gap between the side of the cylinder away from the Sun would be 1/15th of a mm (millimeter) longer than the gap on the side closest to the Sun. Even if we scaled the cylinders up to a 1,000 km across and 10,000 km long, it's only 65 m.

Just to give some idea of the immensity the ring, it would take 97 million of the smaller 10 km long cylinders to circle the Sun. Even with the bigger 10,000 km long cylinders, there will still be 97,000 of them.

And a hyperloop would make sense running through the center of all the cylinders. In fact, that could be the unobtanium -- instead of a scrith ribbon, have a giant string of some wondrous material, similar to proposed orbital beanstalks, but much larger in scale, which forms a continuous loop around the sun. I'm not sure how thick the string would be, but it would be substantial in size yet much smaller than each cylinder. Give it magnetic or gravitic or quantum properties (https://www.youtube.com/watch?v=ZHT6NIebSfU), which the modules use to "attach" (without contact) to the string. This would be done by rings, at least one at each end of a cylindrical module, perhaps many running along the inner axis. The rings would encircle the string, maintaining a constant distance, thanks to the magnetic/gravitic/quantum properties. Monorails or the equivalent could run down the string, though that might make the most sense if we make the string hollow -- need to think about it a bit more.

Quote from: GeekyBugle on May 23, 2022, 03:23:09 PM
Yes, why did they choose a torus and not a ring, that's a kind of important question I hadn't thought about.

Some civilization has an active patent on the ring design.  You don't want the galactic patent office after you.

Why not an artificial star?  Surely if they can build this huge torus they can create  an artificial star just the right size.

Better yet a hollow sphere with a star in the center.

Quote from: GeekyBugle on May 24, 2022, 01:59:18 AM

Quote from: HappyDaze on May 23, 2022, 04:08:33 PM

Quote from: GeekyBugle on May 23, 2022, 03:56:31 PM

Quote from: Pat on May 23, 2022, 03:29:18 PM

Quote from: GeekyBugle on May 23, 2022, 03:23:09 PM
In the orbit of mercury and then you have no photosyntesis because you lack enough light.

Are you confusing Mercury with one of the outer planets?

No, you need to block it to not get cooked/blinded. Light carries heat too.

Isn't that (radiant heat) pretty much the only way a star gives off heat? I suppose mass elections can give off heat too, but I'd imagine it's tiny in comparison (unless you're unfortunate enough to get hit by one).

I'm going to assume you're not talking about elections nor erections, so it leaves what? ejections? As in solar flares? yeah that's the other way a star gives off heat. I mean if it hits you you get engulfed by a flame at 10's of millions of kelvins.

Yeah, should have been "ejections" up there. Damn autocorrect.

Quote from: VisionStorm on May 23, 2022, 04:40:03 PMEven if it were to still circle a star, this thing would need to be so huge as to beg credulity.

The smallest star we have ever found is EBLM J0555-57 which is about the size of Saturn with a mass 85 times that of Jupiter. Any civilization setting out to build such a structure could pick and choose what size star they want so the size of the ringworld is flexible (but still huge). That fact that people in this thread are using our Sun as a basis is just an example of Earthling bias.

I also agree that having it orbit around a star is a unnecessary. If you are making it a tube, then there isn't any reason for one of the sides of the tube to be transparent to let in light as it would be easier to just use a massive heat lamp moving across the inner surface of the tube to provide the necessary light and heat. At that point all you need is a sufficient power source.

But ultimately, a dyson sphere or ringworld is utterly pointless. Any civilization sufficiently advanced to build such a thing wouldn't have a need for such a unstable design. If they need living space, it would be much easier to build a few artificial planets. These would be self contained and not rely on a magical substance to keep the entire thing from tearing itself apart. I think that a massive ring of hundreds of artificial planets orbiting the same star would be a more original and more useful RPG campaign design as each planet could have it's own unique atmosphere, gravity, and climate. At that point all you would need to do is decide how to move from one to another, such as a portal, a regular space taxi system, or even a giant canon that shoots you from one planet to the next. 

Again, I've asked twice but I still don't know the OP's point in making such a thing. Is this for a fantasy RPG campaign? Sci-fi? Do the people living there know what they live upon? Do they have technology to understand it? Can they fix it or control it in any way? Unless these questions are answered, there isn't much point in discussing potential designs.

Quote from: hedgehobbit on May 24, 2022, 08:52:36 AM
But ultimately, a dyson sphere or ringworld is utterly pointless. Any civilization sufficiently advanced to build such a thing wouldn't have a need for such a unstable design. If they need living space, it would be much easier to build a few artificial planets. These would be self contained and not rely on a magical substance to keep the entire thing from tearing itself apart. I think that a massive ring of hundreds of artificial planets orbiting the same star would be a more original and more useful RPG campaign design as each planet could have it's own unique atmosphere, gravity, and climate. At that point all you would need to do is decide how to move from one to another, such as a portal, a regular space taxi system, or even a giant canon that shoots you from one planet to the next. 

That's not that far from better conceptions of a Dyson sphere. A lot of not very good sf (Star Trek comes to mind) default to a Dyson sphere as a literal shell, but that makes little sense. The point of a Dyson sphere isn't about enclosing a star in something solid, rather it's about capturing the entire energy output of a Sun. The "shell" could be a swarm of objects that together occlude all the electromagnetic emissions. These could could be many giant reflective mirrors just a few atoms thin, mixed in with a wild array of habitats in concentric but offset orbits. This allows a Dyson sphere to develop gradually, instead of requiring a single massive engineering project, and doesn't have the same issues with gravity, tensile strength, and all the other problems. I suggested a similar partial Dyson sphere earlier in the thread, with multiple toruses in different orbits.

Quote from: DocJones on May 24, 2022, 08:22:32 AM

Quote from: GeekyBugle on May 23, 2022, 03:23:09 PM
Yes, why did they choose a torus and not a ring, that's a kind of important question I hadn't thought about.

Some civilization has an active patent on the ring design.  You don't want the galactic patent office after you.

Why not an artificial star?  Surely if they can build this huge torus they can create  an artificial star just the right size.

Better yet a hollow sphere with a star in the center.

Yes, exactly, The Niveans are known to enforce their patents very harshly.  ;D

Quote from: HappyDaze on May 24, 2022, 08:38:21 AM

Quote from: GeekyBugle on May 24, 2022, 01:59:18 AM

Quote from: HappyDaze on May 23, 2022, 04:08:33 PM

Quote from: GeekyBugle on May 23, 2022, 03:56:31 PM

Quote from: Pat on May 23, 2022, 03:29:18 PM

Quote from: GeekyBugle on May 23, 2022, 03:23:09 PM
In the orbit of mercury and then you have no photosyntesis because you lack enough light.

Are you confusing Mercury with one of the outer planets?

No, you need to block it to not get cooked/blinded. Light carries heat too.

Isn't that (radiant heat) pretty much the only way a star gives off heat? I suppose mass elections can give off heat too, but I'd imagine it's tiny in comparison (unless you're unfortunate enough to get hit by one).

I'm going to assume you're not talking about elections nor erections, so it leaves what? ejections? As in solar flares? yeah that's the other way a star gives off heat. I mean if it hits you you get engulfed by a flame at 10's of millions of kelvins.

Yeah, should have been "ejections" up there. Damn autocorrect.

The only reason I miss it here it's because I can make a spelling error and don't notice. But I only used the forum's correction system, not an automatic one.

Quote from: hedgehobbit on May 24, 2022, 08:52:36 AM

Quote from: VisionStorm on May 23, 2022, 04:40:03 PMEven if it were to still circle a star, this thing would need to be so huge as to beg credulity.

The smallest star we have ever found is EBLM J0555-57 which is about the size of Saturn with a mass 85 times that of Jupiter. Any civilization setting out to build such a structure could pick and choose what size star they want so the size of the ringworld is flexible (but still huge). That fact that people in this thread are using our Sun as a basis is just an example of Earthling bias.

I also agree that having it orbit around a star is a unnecessary. If you are making it a tube, then there isn't any reason for one of the sides of the tube to be transparent to let in light as it would be easier to just use a massive heat lamp moving across the inner surface of the tube to provide the necessary light and heat. At that point all you need is a sufficient power source.

But ultimately, a dyson sphere or ringworld is utterly pointless. Any civilization sufficiently advanced to build such a thing wouldn't have a need for such a unstable design. If they need living space, it would be much easier to build a few artificial planets. These would be self contained and not rely on a magical substance to keep the entire thing from tearing itself apart. I think that a massive ring of hundreds of artificial planets orbiting the same star would be a more original and more useful RPG campaign design as each planet could have it's own unique atmosphere, gravity, and climate. At that point all you would need to do is decide how to move from one to another, such as a portal, a regular space taxi system, or even a giant canon that shoots you from one planet to the next. 

First off I LOVE your idea of a ring of worlds, it's the fleet of the worlds. How many AU would each planet need to be from each other not to tear each other appart?

Quote from: hedgehobbit on May 24, 2022, 08:52:36 AM

Again, I've asked twice but I still don't know the OP's point in making such a thing. Is this for a fantasy RPG campaign? Sci-fi?

Second, I thought the title of the thread answered that? It's Sci-Fi of a high handwavium and unobtanium sort.

Quote from: hedgehobbit on May 24, 2022, 08:52:36 AM

Do the people living there know what they live upon? Do they have technology to understand it? Can they fix it or control it in any way? Unless these questions are answered, there isn't much point in discussing potential designs.

That's part of the reason for the thread, my idea was to collectivelly create an OGC setting, free for anyone to use, in The Ringworld the "natives" don't know they live in an artificial structure and though there's technology to fix it they don't know where or how to use it.

Of course that doesn't have to be that way, and in the novels this is true only of the small fraction that's explored.

Welp, while the Klemperer Rosette seems like a solution that needs no "magic" to remain stable turns out that's not true. Each body in the Rosette needs engines to keep it always in place counteracting any force that might push/pull it out of it's perfect placement in the construct.  So engines attached to a planet, powerful enough to move it (yes it needs more than the one engine) that somehow don't tear the thing appart nor destroy the ecosystem when fired.

Source: https://en.wikipedia.org/wiki/Klemperer_rosette (https://en.wikipedia.org/wiki/Klemperer_rosette)

One partial solution is to use a hexagonal rosette, and then orbit them around a white dwarf. That's a more stable configuration because the planets will all sit in each other's Lagrange points. And you can keep the planets closer together, because with a smaller sun the goldilocks zone should be closer (maybe 0.01 AU, per this) (https://www.technologyreview.com/2011/03/17/23884/white-dwarfs-habitable-zones-and-other-earths/). The problem is there is some debate about the suitability of white dwarfs, but in fiction when the answers is unsure you can just pick the one you prefer.

The basic issue with lots of planets is the three-body problem: Any system with more than 2 objects in orbit is inherently unstable, over long periods of time. You'd need a lot of planetary engines. The Solar System is fairly stable right now because the major planets have all cleared their orbits of most of the detritus, but even so the motions of NEOs and so on are inherently unpredictable over time.

Quote from: Pat on May 24, 2022, 08:26:10 PMThe basic issue with lots of planets is the three-body problem: Any system with more than 2 objects in orbit is inherently unstable, over long periods of time.

If this is true, how do the rings around Saturn and Jupiter remain stable?

Quote from: hedgehobbit on June 04, 2022, 10:53:37 AM

Quote from: Pat on May 24, 2022, 08:26:10 PMThe basic issue with lots of planets is the three-body problem: Any system with more than 2 objects in orbit is inherently unstable, over long periods of time.

If this is true, how do the rings around Saturn and Jupiter remain stable?

They're not. The masses of the individual objects in the rings are so small, that we can approximate the results by ignoring their effect and treating the Sun and Saturn (or Jupiter) as a two-body system, which is a reduced form of three body problem. But even that degenerate case, the system will become unstable, over a sufficiently long period of time, which may be hundreds of millions or even billions of years. But objects of more comparable masses, like a string of many Earth-sized planets will become unstable much faster.

Decent summary of the three-body problem: https://www.youtube.com/watch?v=et7XvBenEo8

Quote from: Pat on June 04, 2022, 12:32:38 PM

Quote from: hedgehobbit on June 04, 2022, 10:53:37 AM

Quote from: Pat on May 24, 2022, 08:26:10 PMThe basic issue with lots of planets is the three-body problem: Any system with more than 2 objects in orbit is inherently unstable, over long periods of time.

If this is true, how do the rings around Saturn and Jupiter remain stable?

They're not. The masses of the individual objects in the rings are so small, that we can approximate the results by ignoring their effect and treating the Sun and Saturn (or Jupiter) as a two-body system, which is a reduced form of three body problem. But even that degenerate case, the system will become unstable, over a sufficiently long period of time, which may be hundreds of millions or even billions of years. But objects of more comparable masses, like a string of many Earth-sized planets will become unstable much faster.

Decent summary of the three-body problem: https://www.youtube.com/watch?v=et7XvBenEo8

Furthermore, Saturn's rings are made of mostly dust, the next big mass isn't near enough to have an effect we can see. And the Sun is too far away to break Saturn's pull.

But, posit a big enough comet passing near enough and you quickly see the problem.

Now, in a ring of same mass bodies ANY disrupting influence will rapidly destroy the balance since the ring's bodies are close enough to affect each other even if you place them in their mutual lagrange points. Even with their star's pull.

What we see as a stable orbit really isn't, but it's decay is so slow as to be something that needs billions of years.

Our moon is escaping earth, slowly but surelly moving away from earth's pull.

Just googling around and found this article based on some research done on ring system in 2010.

https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/

The basic gist is that large numbers of planets co-orbiting is actually more stable than a smaller number (and anything less then 7 is unstable). So a ring of 42 earth sized planets could orbit the sun in the same orbit. Plus you could also put multiple rings of planets in slightly different obits (all in the habitable zone) meaning our sun could possibly have 252 total Earths orbiting it. The actual number is based on the ratio of the bigger body to the lesser body. The higher the ratio, the more objects can remain in orbit because they can be closer to one another.

In this arrangement, each planet would be 100 times further away than our moon. By my calculations, this would make the nearby Earths appear to be about 4% of the size of our moon.


Anyway, that's enough for my off topic idea.

Quote from: hedgehobbit on June 05, 2022, 08:39:41 PM
Just googling around and found this article based on some research done on ring system in 2010.

https://planetplanet.net/2017/05/03/the-ultimate-engineered-solar-system/

The basic gist is that large numbers of planets co-orbiting is actually more stable than a smaller number (and anything less then 7 is unstable). So a ring of 42 earth sized planets could orbit the sun in the same orbit. Plus you could also put multiple rings of planets in slightly different obits (all in the habitable zone) meaning our sun could possibly have 252 total Earths orbiting it. The actual number is based on the ratio of the bigger body to the lesser body. The higher the ratio, the more objects can remain in orbit because they can be closer to one another.

In this arrangement, each planet would be 100 times further away than our moon. By my calculations, this would make the nearby Earths appear to be about 4% of the size of our moon.


Anyway, that's enough for my off topic idea.

Very interesting. The system would still be unstable, but that would be over billions of years, which puts it in the same category as the Solar System. So it appears to be a functional solution. I supposed a planetary procession in the same orbit is just a variation on the "clear their orbit"  requirement for major planets, which is what enabled the Solar System to settle down.

Though unfortunately, the journal article it's based on seems to be behind a paywall.

For material, call it stabilized muoinc matter. Beyond known science.

If you want ideas on building incredible structures read Eon by Greg bear. It goes way beyond this.

It was built as a birdhouse or an ant farm, basically a super intelligence wanted to see how lesser advanced races would use it so they could study them. Maybe they wanted to track the development of intelligence.