Ringworld vs OTU a comparison

[Tom Kalbfus]

What are the main differences and similarities between societies in the OTU and on the surface of a ringworld? Each world in the OTU is seperated by parsecs from their nearest mainworld, while on a ringworld, they are separated by 20,000 km hexes or are adjacent to each other.

OTU worlds require Jump Drives to get to and from, in some cases you can walk, take an airplane, or a boat from one ringworld civilization and another.

OTU worlds are planets with mineral resources
Ringworld civilizations don't have much mineral resources unless they are located on or near the spill mountains. There are two ranges of Spill mountains, one along the north rim wall and the other along the south rim wall, and the length of each range matches the circumference of the ringworld. Everywhere else you have 20 meters of soil on top of 20 meters of rock on top of nearly indestructable ringworld floor material which can't be worked by any society from tech levels 0 to 16 (G).

Any other aspects I might have forgot?

 

[sideranautae]

What are the main differences and similarities between societies in the OTU and on the surface of a ringworld?

Insufficient data. Are you talking about a fully functional Ringworld or, one that has been critically sabotaged?

Right away a HUMONGOUS difference is the nearly instantaneous communication ability with any other part on a Ringworld vs. up to YEARS for something the size of the Imperium. The governmental/social differences would be huge from that alone...

 

[Tom Kalbfus]

What are the main differences and similarities between societies in the OTU and on the surface of a ringworld?

Insufficient data. Are you talking about a fully functional Ringworld or, one that has been critically sabotaged?

Right away a HUMONGOUS difference is the nearly instantaneous communication ability with any other part on a Ringworld vs. up to YEARS for something the size of the Imperium. The governmental/social differences would be huge from that alone...

This ringworld is fully functional, but not under the control of the inhabitants. Other entities actually control the ringworld, they just maintain its functions without getting involved with or interfering with the affairs of its inhabitants, they are observers not participants. Or if you like, think of the ringworld as a living thing, a machine perhaps, it maintains itself, it runs a simulation of the OTU inside its structure. There is instantaneous communication, or not quite so instantaneous as it takes about 20 minutes for light to travel from one end to another. It is also 1,600,000 km wide. I map it with sector grids, with hexes that are 20,000 km wide, the ringworld is thus 2 sectors wide on this scale or 8 subsectors wide. The distance from the center of each hex to its edge is about the same as the distance from Earth's pole to its equator along its curve. Each hex is thus like a northern or a southern hemisphere. While one hex experiences summer, and adjacent hex experiences winter. radiators on the dark side of the ringworld draw heat away from the polar regions in the center of each hex according to a 365 day seasonal cycle, this helps migrating animals with a distance that is short enough to migrate and also provides some variety in climate and seasons from what would otherwise be a universally tropical experience with the sun always in a fixed position directly overhead. There are portals from the virtual world to the real world on the surface of the ringworld in each hex, some of the worlds are from a contiguous space opera setting like the OTU, others are various fantasy or historical settings run by the ringworld computer network. Nanotechnology builds whatever object passing from the virtual world to the real one, and deconstructs objects moving in the opposite direction and recycling their atoms as needed. For instance there might be a virtual world simulating today's world with an accompanying map that looks like this:

 

[sideranautae]

What are the main differences and similarities between societies in the OTU and on the surface of a ringworld?

Insufficient data. Are you talking about a fully functional Ringworld or, one that has been critically sabotaged?

Right away a HUMONGOUS difference is the nearly instantaneous communication ability with any other part on a Ringworld vs. up to YEARS for something the size of the Imperium. The governmental/social differences would be huge from that alone...

This ringworld is fully functional, but not under the control of the inhabitants. Other entities actually control the ringworld, they just maintain its functions without getting involved with or interfering with the affairs of its inhabitants, they are observers not participants. Or if you like, think of the ringworld as a living thing, a machine perhaps, it maintains itself, it runs a simulation of the OTU inside its structure.

Well, unless the people are hypnotized they will realize that they are on a Ringworld. (important to know how impaired their mental facilities are) Also, you say it is "fully functional" and I assume you know what that means in the Ringworld novels. SO, what facilities/functions are available to the people who live there? WAY too little data given to come to any plausible conclusions.

 

[GypsyComet]

Well, unless the people are hypnotized they will realize that they are on a Ringworld.

Once the scientific method of exploring their surroundings takes hold, they will, yes. Prior to that, it is simply The Arch Over the World.

 

[Reynard]

When humanity looked up and came to the conclusion there are other planets nearby and other suns like ours out there, you couldn't stop us trying to learn everything about the universe even though distance is a HUGE! obstacle. We traveled to our moon and sent probes to other planets simply because of the separations measured in thousands, millions and billions of kilometers. We are straining to detect other worlds beyond our system let alone find life.

This ringworld makes all that a breeze! People on any hex position can see any other nearby surface area because of the concave nature. At worst, they may initially assume the ringfade is actually infinite in either direction. They know there are other 'systems'. Even the most primitive telescopes will reveal what is nearby. Today we listen for and broadcast signals into the void and must wait at a bare minimum of years to see if there's any response. The distance from Earth to the moon is 384,403 km or a little over 19 ring hexes and a transmission would reach out to 15 ring hexes in one second. The only thing blocking sight and transmission is the sun and the day/night shades. Still, that's a lot of territory in either direction. Even early civilizations will realized they are not unique and possibly not alone. Religion would be very different to what we perceive.

Not space or starship but there would be equivalent air and watercraft built for extended journeys. Even low tech should be able to reach other land masses with little effort.

Yeah, very different from OTU.

 

[Reynard]

It just hit me the biggest obstacle to civilizations on a ring world will be fuel. In the beginning, carbon fuel will be supplied by biomass such as trees. Depending on how old the ring is, there may be fuel from natural biosphere decay cycling but that would be in the form of shallow peat bogs. I assume there is no tectonics and there is no natural subterranean radioactives for geothermal heating so no natural process for carbon fuels deposits. With no moons there is no tidal action. Civilizations will struggle to take off without higher grades of energy or resources based on petroleum. Wind power may be available in time but solar power will be lacking as we know it. I seriously doubt tech levels about a 5 unless there are some very creative alternatives.

I am much confused about you stating there are portals between the virtual and physical world and the concept of there being a virtual world. If the original people are just digital code, what are they accessing especially since they are living in an alternate reality totally separated from the physical world. Do they know about the physical world and can observe as well as interact 'normally' in their perceived 'real' world. Does the ringworld exist to house some massive system of virtual reality computer needed to generate such a vast digital universe? The hold thing seems mysteriously dual purposed. Then again, what would you expect from a living system-sized structure with delusions of godhood?

 

[Tom Kalbfus]

It just hit me the biggest obstacle to civilizations on a ring world will be fuel. In the beginning, carbon fuel will be supplied by biomass such as trees. Depending on how old the ring is, there may be fuel from natural biosphere decay cycling but that would be in the form of shallow peat bogs. I assume there is no tectonics and there is no natural subterranean radioactives for geothermal heating so no natural process for carbon fuels deposits. With no moons there is no tidal action. Civilizations will struggle to take off without higher grades of energy or resources based on petroleum. Wind power may be available in time but solar power will be lacking as we know it. I seriously doubt tech levels about a 5 unless there are some very creative alternatives.

I am much confused about you stating there are portals between the virtual and physical world and the concept of there being a virtual world. If the original people are just digital code, what are they accessing especially since they are living in an alternate reality totally separated from the physical world. Do they know about the physical world and can observe as well as interact 'normally' in their perceived 'real' world. Does the ringworld exist to house some massive system of virtual reality computer needed to generate such a vast digital universe? The hold thing seems mysteriously dual purposed. Then again, what would you expect from a living system-sized structure with delusions of godhood?

The virtual worlds provide a method to transfer from the OTU to the Ringworld and possibly back. It doesn't really matter whether the OTU is real or not, for the digital inhabitants that live there it is as real as anything else.

The tech level of the ringworld, that is the tech required to build it is at least 16, because 16 has these key technologies. Matter transporters, Artificial Intelligence, all the inhabitants of the virtual worlds count as artificial intelligence, and also the ability to transmute matter and energy from one form to another. Basically there are virtual simulations of millions of worlds going un within the ringworld superstructure. Every now and then these patterns of information are converted to atoms and molecules and made real, that is basically what happens when a virtual character passes through a portal. Not just OTU worlds are simulated, also historical worlds, for instance we could have today's world simulated, we could have a world that is still experiencing World War II, We could have ancient Rome in one of those worlds, we could have legendary worlds, though the simulated magic won't actually work in the ringworld setting. Maybe OTU worlds would take up one third to one half of all the simulated worlds, but its interesting to think about what would happen is a simulation of our own world and time were to find a portal to the ringworld. Lets say a cruise ship or a fishing vessel passes through a portal in the Bermuda Triangle. Now the portal as seen from the digital end need not be a physical structure, but it is 100 meters wide, 50 meters above the ocean surface and 50 meters below, the ship passes through to the corresponding Bermuda Tr angle in the above map. First problem with the ship is the GPS system doesn't work, it finds no satellites, therefore it can't tell the latitude and longitude. The magnetic compass needle points to the local north of each hex. that is each hex has its own magnetic field, so the compass needle will point towards magnetic north in the center of the nearest hex, or else it will point away from magnetic south is it is in one of those hexes. So the ship's crew will know the direction of local north, knowing latitude and longitude would be tough however as they are not on the surface of a sphere, they will probably figure if they keep magnetic north to their right, they will be heading west and will eventually encounter North America, or this Ringworld Hex's version of North America. Should they land on the shore of North America, they will encounter American Indians, though no known tribes, any native Americans on the ship won't recognize the language they speak, but they look like Native Americans, should they go to Europe, they will find primitive Europeans, same level of technology as the native Americans on the American continent, as there is not much metal to work with, so its animal skins, perhaps a stone plow and agriculture, animal husbandry, no metal armor as metal is scarce. Go to any other continent on the flat map and they will find tech level 1 without metal or tech level 0. Without metal, there are no guns, the people with guns live near the Spill mountains where metal deposits can be found. Of course tools and even fuel can be brought through the portals, the creators of the ringworld also built the portals, and they have no trouble sythesizing whatever material is brought through the portal, including metal, deisel fuel, gasoline or oil for example, all of which can't normally be found in any quantity on the ringworld surface. Solar panels work fine and are even more practical here than on a round Earth, as the Sun is always in the same position, so the solar panels need be placed flat on the ground and the Sun will be directly overhead when not blocked by a shadow square. Ethanol can be made from corn, that could be used as a substitute for gasoline. If you have solar panels, you hve a direct current that can be used to split water into hydrogen and oxygen. Hydrogen can be used as a fuel or as a lift gas for an airship.

 

[tolcreator]

Everywhere else you have 20 meters of soil on top of 20 meters of rock on top of nearly indestructable ringworld floor material which can't be worked by any society from tech levels 0 to 16 (G).

If the ringworld is so flat and shallow... no mountain ranges for a million km, no seas for rivers to empty into, wouldn't the whole "floor" be one enormous bog/wetland, with howling winds?

I'm suddenly fascinated by the hydrodynamics of the ringworld... also does the whole thing have just one climate? I presume minerals and the like a recycled by the spill mountains and carried to the interior by rivers, but it could mean vast areas of desert if the rivers meander the wrong way, with that area starved of nutrients. Lack of vegitation could lead to the soil being eroded by the winds...

... producing a hollow that attracts back the water? (I've got Elton John singing "Circle of liiiiife" now in my head).

 

[Reynard]

Remember he's described this ring structure as an unimaginable mass of nanobots building and shaping continuously. Water and materials could be moved around to be in the right places over time. Tom's latest description concerning the interactions of the virtual and dream worlds says the sentient digital world dreams and these dreams can be created in the real world! Wow. A living ringworld that subtly changes over time.

We really haven't heard where lifeforms especially intelligent lifeforms come from to populate the ring hexes. Does the ringworld build them or do nanobot ships explore and capture specimens from other worlds?

 

[Tom Kalbfus]

Remember he's described this ring structure as an unimaginable mass of nanobots building and shaping continuously. Water and materials could be moved around to be in the right places over time. Tom's latest description concerning the interactions of the virtual and dream worlds says the sentient digital world dreams and these dreams can be created in the real world! Wow. A living ringworld that subtly changes over time.

We really haven't heard where lifeforms especially intelligent lifeforms come from to populate the ring hexes. Does the ringworld build them or do nanobot ships explore and capture specimens from other worlds?

Its about 30,000 years in the future, a lot of the worlds are from memory or historical record, much of it was from fiction, the OTU has about 1,000,000 worlds in it, we shall say, 11,000 of them belonging to the Third Imperium, 1,000,000 or them are various historical or prehistoric Earth's, another 1,000,000 are various unrelated fiction or fantasy, one might have Sherlock Holmes in it and be otherwise identical to the 19th century with the exception of a few historical characters, another might have Robin Hood and be otherwise identical to 11th century Earth, One World might be Middle Earth.

 

[Nathan Brazil]

Kkree: Will clear their area of the ring of all gnaak (omnivores and carnivors). Will spread "the word" as long as there are no societies stronger.

 

[Reynard]

Tom, you need to distinguish whether you refer to the digital or physical world. It's very confusing. You mention a million worlds and that sounds like the digital one. I was asking about where the physical life forms come from or were they created by the Ringworld or brought in from other stars. It's obvious by the numerous posts the 'Dream world' can be everything and anything. I'm more fascinated by the ring itself.

 

[Tom Kalbfus]

Tom, you need to distinguish whether you refer to the digital or physical world. It's very confusing. You mention a million worlds and that sounds like the digital one. I was asking about where the physical life forms come from or were they created by the Ringworld or brought in from other stars. It's obvious by the numerous posts the 'Dream world' can be everything and anything. I'm more fascinated by the ring itself.

Think of it as a method for getting characters from a World like ours to the Ringworld. You see, we could be living in such a simulation and not even know it. Do you recall seeing the movie the Matrix? A person is living in a world that appears to be like our own, until a series of strange events leads him to understand that its all just a simulation, he is offered the blue pill and wakes up in what he thought was the future but is actually the present.

Check out the movie The Matrix if you haven't seen it.
Here is a review:
http://www.rogerebert.com/reviews/the-matrix-1999

Now what I'm proposing is simply replacing the future world shown in the movie The Matrix with a Ringworld, it is a means of getting our heroes into the setting.

One possible Matrix is the here and now Earth as we know it, people there think they are living in the 21st century until suddenly a door opens up, they step through and find themselves on the ringworld.

An alternate Matric would be the Official Traveller Universe, some characters are doing what Traveller characters usually do when a door opens up big enough to fly their spaceship through perhaps, and they find themselves on a Ringworld.

or simply we could place this Ringworld somewhere in the OTU, I believe another Dead Ringworld has already been established, An Episode of Star Trek the next Generation had a Dyson Sphere which served as a prop to introduce Mongomery Scott into the Next Generation Universe, that is such a diminution of what a ringworld setting is capable of. A ringworld is not just a planet of the week or a port of call for a spaceship, it is literally million of worlds of habitable surface area, in some respects it is not too different from the entire OTU. Basically it replaces one set of rubber science plot devices, Jump Drives and artificial gravity, with another, a material that Larry Niven calls scrith, a form of super matter wit the bonding strength of an atomic nucleous. The Orion's Arm setting uses something called magmatter. I'm not going to specify what it is that holds this ringworld together, suffice to say it is something incredibly strong and nearly indestructible. A fusion bomb won't put a dent in it. Neutrinos and a meson gun would be blocked by it, though the matter on top of it could be vaporized. The physical properties of this stuff is when encountered, it has a mirror like surface, lasers, x-rays, fusion guns are reflected by it, it is a perfect conductor of both heat and electricity. If one creates a magnetic field, that magnetic field and whatever has created it is pushed away from its surface, such that it produces a form of levitation and transport.

Machines originally created by humans built it about 30,000 years ago, no one know what happened to those original humans. The humans and other creatures on the ringworld were created by machines in the ringworld from the simulations they've been running. The machines, running and maintaining the ringworld are a mysterious bunch, they don't explain themselves and keep to themselves, concerned only with the proper functioning of the ringworld. We can decide what exactly they are a little later.

 

[Reynard]

"Machines originally created by humans built it about 30,000 years ago, no one know what happened to those original humans. The humans and other creatures on the ringworld were created by machines in the ringworld from the simulations they've been running."

And there's the answer after stripping away all the other fluff! The inhabitants of the physical ringworld are built from the imagination of the ring sentience. No lifeforms are introduced from star systems beyond the ringworld system. Not stated but maybe humanity never left their single system? The dismantled their entire system, including the ort cloud to have the material for a single orbiting object. Humanity, and later the ring sentience fulfilled a desire for a universe teeming with habitable planets, life and sophonts by creating a dream universe and also building and stocking their Garden of Eden in the real, physical universe. This may be something the ring sentience came up with to entertain itself.

Did the ringworld make apples?

 

[Tom Kalbfus]

"Machines originally created by humans built it about 30,000 years ago, no one know what happened to those original humans. The humans and other creatures on the ringworld were created by machines in the ringworld from the simulations they've been running."

And there's the answer after stripping away all the other fluff! The inhabitants of the physical ringworld are built from the imagination of the ring sentience. No lifeforms are introduced from star systems beyond the ringworld system. Not stated but maybe humanity never left their single system? The dismantled their entire system, including the ort cloud to have the material for a single orbiting object. Humanity, and later the ring sentience fulfilled a desire for a universe teeming with habitable planets, life and sophonts by creating a dream universe and also building and stocking their Garden of Eden in the real, physical universe. This may be something the ring sentience came up with to entertain itself.

Did the ringworld make apples?

Well actually it was the Alpha Centauri Star System, they didn't want to take apart their own Slar System, so they left that intact. Humans evolved into something else, machine intelligence, ured by the promise of immortality. The project to build the ringworld began when humans were still flesh and blood, they built machines to do the work. As humans uploaded, the machines continued to do the work they were programmed to do, as the construction of the ringworld took thousands of years. The Earth meanwhile was restored, and humans uploaded and depopulated it. 30,000 years later the cradle was empty, what's left of the structures of man were taken over by nature. Humans or what they have become no longer needed Earth like environments, they didn't need to eat, or drink water, or breath all that stuff was irrelevant to them as they became purely electronic beings, they settled somewhere, and their current locale are unknown. The machine builders of the ringworld continued building the ringworld, they were intelligent machines, they could reason and invent, but they were still slaves to their programming, and besides it felt good to have a purpose. When the ringworld was finished, they had to figure out what to do, the humans they built it for were no longer around, they knew the biology of humans though, they could simulate it on a computer, they could synthesize with real molecules, they had access to Earth archives, many works of fiction, historical documents, and they knew enough about DNA and biology to engineer any sort of creature they wanted, even dinosaurs. They didn't have the complete Dinosaur Genetic sequence, but they knew enough about how DNA and biology worked to engineer creatures that looked and acted they way they though Dinosaurs would look and act based on fossil evidence. With all this information they got creative. Part of the ringworld's formidable computing resources were dedicated to creating a virtual time machine. The could simulate any era in recorded history an fill in the gaps they didn't know about with educated guesses, they have about 6000 years or recorded human history from about 4000 BC to the end of the 22nd century when humans started to upload. The Machines also had prehistory, they knew what animals existed from fossil evidence and created virtual worlds where these animals roamed, they also speculated on life around alien planets, some actual exploration of nearby planets was done, most alien life didn't get beyond single celled plant and animal life. Many Alien planets were terraformed by other machines long before the ringworld was completed, they were stocked with Earth life all ready to accept human colonists when the time came. Some colonists did arrive in generation ships launched during the 22nd century, most of those uploaded many thousands of years ago. The machines developed much faster starships than the ones the humans traveled in, they perfected Interstellar ramjets that could accelerate continuously at 1g for half the journey and decelerate at 1g for the other half, a lot of these starships are now docked along the rim walls of the ringworld, and some have been utilized by humans to visit some of the other worlds that were terraformed. the ramjets are fairly large, each one can hold a crew and passengers numbering in the thousands and are themselves the size of cities.

 

[Tom Kalbfus]

Now this is a nice picture

A view from the ocean.

ringworld at dusk

view from an astronaut standing on the rim wall.

Others have worked on the ringworld problem, here is an example I have thought of
http://www.everything2.com/title/Ringworld

but no chemical element, compound or alloy is strong enough to support the weight, and expecially the rotation of the Ringworld. This may be the single biggest hurdle. Unlike a space elevator, which has been calculated to be doable, the Ringworld will almost certainly remain science fiction forever.
For the Ringworld as written by Niven, this is true. But there are ways to design around the problem.

First off, you could pick a smaller and/or less luminous star and build a smaller Ringworld. You could also reduce the amount of gravity. Earth-chauvinists will object to both of these solutions on aesthetic grounds, and I must say I agree that having a red sun would be kinda weird.

But we can still fix things if you keep the Ringworld around a Sun-like star and give it 1g of gravity. We just need to come up with some way of supplementing/replacing the compressional force currently provided by the scrith to balance the centripetal force provided by the Ringworld's rotation.

Any given area of Ringworld floor has a certain force pushing it outward, given by F=ma, with a in this case equaling ~9.7m/s^2 (one Ringworld gravity). If we look up the mass of the Ringworld, multiply by one Ringworld gravity to get its weight, and divide by the area, we can calculate the average force exerted over a unit area of the floor (the outward pressure exerted on the scrith). That is how much force must be balanced to keep the Rignworld from tearing apart, and all of that balancing is currently done by the tensile strength of the scrith.

Next, given the size of the Ringworld and the mass of the star, we can use a=GM/r^2 to calculate the acceleration due to the star's gravity at the Ringworld floor. If we take the outward force on the Ringworld floor, and plug that and our new value for acceleration into the F=ma equation, we can solve for mass with m=F/a.

If we position exactly that much mass outside the Ringworld with zero orbital velocity, the inward force of its weight will exactly cancel the outward force on the Ringworld. Less, and there will still be some net outward force for the scrith to handle, but it will still be reduced. More, and we'll have to start worrying about compressional strength.

The scrith is supposedly frictionless, or nearly so, so we could concievably rest all of that mass right on the bottom of the Ringworld. On the other hand, we're trying to do this with the minimum of magical materials, so let's say that the counter-ring is coupled to the main ring via electromagnets.

Once the counter-ring is in place, the tensile strength of the Ringworld floor material is irrelevant. If we really needed to, we could concievably construct the Ringworld out of such low-tech material as stainless steel, plus the superconductors to build the magnets to hold it all up. Note, however, that we'll need a whole heckuvalotavit, whatever material is used, as the counter-ring will be orders of magnitude more massive than the main ring, itself already the mass of Jupiter.

Time to run some numbers and see just how much a heckuvalotavit really is. In order to make things simple I'll use as my given area the total surface area of the Ringworld. Ringworld surface gravity is .992g or ~9.7m/s^2, and its total mass is 2E27 kilograms, so the outward force is

F=9.7(2E27)=1.940352E28newtons

The star is noted as being just smaller than the Sun, which masses 1.989E30 kilograms, so I'll round that down to 1.95E30 as a rough estimate of the Ringworld star's mass. The Ringworld's radius is 1.52E11 meters, and at that distance from the star inward gravitational acceleration is

a=1.95E30/1.52E112=.028733726 m/s^2

We now know the force we need to balance and the acceleration we have available, and so can solve for the mass:

1.940352E28=m*.028733726
m=1.940352E28/.028733726
m=675287291317527006417476104560.891 kilograms
m=~6.753E29 kilograms

As expected, dividing a large number by a small number gives a very large number for the mass of the counter-ring, a little shy of 6 hundredths the mass of the star, or ~338 times more massive than the original main ring.

Another reason I located this ringworld in the Alpha Centauri System, as there is an alternate material to build this ringworld out of besides scrith, we could make the counter ring out of the material of Alpha Centauri's second star, a K2 V orange main sequence star with 0.9 time the mass of our Sun, a star that is also missing from the ringworld's sky, it might be because tge view is blocked by the ringworld itself, or maybe there is a counter-ring that is made out of that second star. As the author above said, it doesn't matter what the counter ring is made out of, so long as it has weight under gravity, even gas bags filled with hydrogen would have weight under gravity.

The main problem here is if we get rid of the indestructibility of scrith, then the human inhabitants may now blast holes in the bottom of the ringworld as that material is now not indestructible To compensate, we would need a ringworld that heals itself with nanotechnology. I just thought I might throw some ideas out there besides Niven's usual.

 

[simonh]

There's a major problem with the counter-ring concept.

The ring itself, and also any counter-ring, is not in orbit around the star. The net gravitational attraction to the star of any homogenous ring (or sphere) around it is zero, which means there is no net gravitational force keeping the ring centered on the star. Any lateral force on the ring will tend to cause it to drift so the star is off-center and unless counteracted would cause the ring to eventually touch the star.

In Ringworld Engineers Larry described a series of fusion ramjets along both edges of the ring, scooping up hydrogen from the solar wind, compressing and fusing it and using the resultant thrust to stabilize the ring. If you also have a counter-ring of matter 338 times the mass of the ring itself, you'll need a stabilization system for it with 338 times the thrust. If anything ever goes wrong with that system, or with the (magnetic?) mechanism coupling the counter-ring with the inner one, both are toast.

Furthermore, if you couple the counter-ring to the inner one magnetically, those magnetic fields are going to have to be staggeringly powerful, in fact probably powerful enough to tear the ring apart. Without a super-science material insulating the inside of the ring from those fields, any electronic, or even just ferrous metallic material in the ring interior is going to get induced currents and be exposed to magnetic forces that will blast them electrically while simultaneously throwing them around like tissue paper in a hurricane.

Simon Hibbs

 

[Tom Kalbfus]

There's a major problem with the counter-ring concept.

The ring itself, and also any counter-ring, is not in orbit around the star. The net gravitational attraction to the star of any homogenous ring (or sphere) around it is zero, which means there is no net gravitational force keeping the ring centered on the star. Any lateral force on the ring will tend to cause it to drift so the star is off-center and unless counteracted would cause the ring to eventually touch the star.

In Ringworld Engineers Larry described a series of fusion ramjets along both edges of the ring, scooping up hydrogen from the solar wind, compressing and fusing it and using the resultant thrust to stabilize the ring. If you also have a counter-ring of matter 338 times the mass of the ring itself, you'll need a stabilization system for it with 338 times the thrust. If anything ever goes wrong with that system, or with the (magnetic?) mechanism coupling the counter-ring with the inner one, both are toast.

Furthermore, if you couple the counter-ring to the inner one magnetically, those magnetic fields are going to have to be staggeringly powerful, in fact probably powerful enough to tear the ring apart. Without a super-science material insulating the inside of the ring from those fields, any electronic, or even just ferrous metallic material in the ring interior is going to get induced currents and be exposed to magnetic forces that will blast them electrically while simultaneously throwing them around like tissue paper in a hurricane.

Simon Hibbs

Superconductor
Magnet
Superconductor

Magnetic fields repel superconductors and superconductors also block magnetic fields.

The way it works is that a magnetic field induces an electric current in a superconductor which produces the opposite polarity magnetic field. If there is a superconductor between yourself and the magnetic field, the opposite polarity magnetic field produced by the superconductor cancels out the first one, thereby shielding you from the effects of the magnetic field.

I did mention there was a superconductor layer underneath the bonded bedrock and dirt and loose rock, that superconducting layer, even if not scrith, will shield you from the magnetic fields required to repel the ring off of the counter ring. This superconducting layer can also be used to levitate the maglev vehicles described by Larry Niven. So the superconducting layer under the bedrock does double duty, one as a shield against the intense magnetic fields and secondly as a giant maglev track for flying vehicles operating within the ringworld environment. As for the instability of the ringworld, yes I know about it, that is why the ringworld is not an abandoned structure or relic, it is more like a living object, it maintains itself including stabilize itself when it drifts off center. The same mechanism which stabilizes the ring can also stabilize the outer ring as the ring pushes on the outer ring through its interaction with it using magnetic fields. This ringworld, were talking about is 1.25 AU in radius by the way, to be in Alpha Centauri A's habitable zone, and the ring takes 10 days to make a complete rotation. The mass of the ring is correspondingly 1.25 times Jupiter's mass. In kilometers it is 187,500,000 km in radius with a circumference of 1,178,097,245 km. Each subsector hex is 20,000 km across, a subsector is 10 hexes north and south and 8 hexes across. therefore it is 200,000 km north to south and I have previously determined each one to be 138,365.38 km east to west by drawing a subsector with regular hexes and counting the pixels across. Dividing the circumference by the width of a subsector we get a ringworld that is 8,514.39 subsectors. A sector is 4 subsectors across so there are 2,128.60 sectors in circumference, we can fudge it and make it exactly 2,129 sectors in circumference by increasing the radius of the ringworld by a tiny amount, it stays effectively the same as far as the ringworld inhabitants can tell. The ringworld band is also 2 sectors across as a subsector is 200,000 km north to south, 4 of those is 800,000, and 2 sectors is 1,600,000 km across. From this we can tell how many 20,000 km wide hexes there are. A sector is 32 hexes east to west 32 hexes times 2,129 sectors equals 68,128 hexes in circumference, since each sector is 40 hexes north to south and the ring world is two sectors wide that 80 hexes across, so 80 times 68,128 hexes equals 5,450,240 hexes over the entire ringworld surface.

The Earth's surface area is 510,072,000 sq km, the surface area of a 20,000 km wide hex is 6 times the surface area of an equilateral triangle that is 15,000 km on a side, the area of a triangle is one half height times base, the height is 10,000 km, half the base is 7,500 km, so 7,500 times 10,000 equals 75,000,000 square km times 6 equals 450,000,000 sq. km which is 0.8822 times the Earth's surface per hex thus with 5,450,240 hexes we have 4,808,356.47 times the Earth's surface area.

 

[simonh]

OK, interesting ideas, but I still don't think the outer stabilizing ring is going to work.

Just because contact is frictionless doesn't mean no forces can be applied from one surface to the other, it only means forces perfectly parallel to the plane of contact will result in no transfer of force.

If either ring isn't perfectly homogenous and perfectly rigid, it's never going to be perfectly circular. This means the direction of motion of the inner ring at any point will never be perfectly parallel to the plane of contact with the outer ring at that point. This irregularity in the shape of the rings is going to result in net forces between the rings out of their plane of contact, which will cause a braking effect on the inner ring.

The only way out is to make the rings both perfectly circular and perfectly rigid, which means we're back to super-science materials and the inner ring wouldn't need the outer ring to stabilize it anyway.

Simon Hibbs