Ringworld setting: A world without spaceships

[Tom Kalbfus]

One idea is to use the traveler rules to simulate characters exploring a megastructure such as a ringworld or a Niven Ring, this is a subsetting to my wormholes campaign, the PCs arrive in a spaceship, and use the vehicle rules to explore the surface of this megastructure, with a surface area equivalent to millions of Earths, this amounts to its own separate setting. I was wondering if you think this could be an engaging setting as your standard space opera where you explore different planets. this ringworld is separated by about 3.8 light years from the nearest wormhole opening, and their are no FTL drives, so everybody is travelling around in a slower than light spaceship. It just so happens that this ringworld is in our own solar system in the year 11,800 AD, the nearest wormhole is in the Barnard system at that distance, and that wormhole brought character in from the year 2491 AD, from the old Solar System prior to this ringworld's construction. the ringworld is 1 AU in radius around our own Sun, was a width of 1 million miles, and rotates once every 9 days for gravity, a shadow ring filters the sunlight reaching the ringworld in places blocking all of it for night, and in others filtering out only some, producing day and night, colder climate zones closer to the ringworld's edges and seasonal cycles simulating climate on a planet's surface. the rings inhabitants include humans and aliens, familiar and unfamiliar ecologies, and weird and alien technologies. There are patrons interested in obtaining knowledge about this place, but the lack of wormhole connections to this system means that it does not upset the local interstellar political balance. The ringworld's technological inhabitants mostly don't travel in space, those that do are mostly traveling to other parts of the ringworld, and they are unaware of the wormhole network and tend to thing of the Ringworld as their entire universe.

 

[Reynard]

So, some super advanced race removed humanity from Earth for a while then deconstructed the entire solar system except for the sun to build a ring fully terraformed for various alien races including the reseeded humans in a period somewhere in the range of 10,000 years then left (maybe). Earthring is isolated from other systems except for generational STL travel. No need for spaceships because there's nothing but the ring and the sun. It's.... a zoo of interplanetary proportions where anything is possible by boat or plane. Be interesting if humans wake up one day and go about their lives until they begin to realize they have no memory of their past.

Cool.

I still have my Chaosium boxed Ringworld RPG set.

How did the ship get to Bernard's Star without FTL or was there a generational colony there? How could a wormhole bring in a ship from the old Solar System if it has no wormhole? Once again, is Bernard's Star a colony and one of its wormholes glitched to send them through both time and space?

 

[Tom Kalbfus]

A wormhole is also a time machine, each one connects two points in space and time. the original wormhole network was not built by humans, but by aliens one billion years ago, due to slightly different gravitational potential, a time difference built up between the two ends of the wormhole connecting the Sol System with Barnard's star which amounted to 9,309 years. the Sol end of the wormhole is in 2491 AD, the Barnard's Star end of it is in 11,800 AD. Humans discovered this ancient wormhole network, and used it to colonize different stars, this one going to Barnard's star goes furthest into the future, and at this point in time Barnard's Star also happens to be at its closest to the Sun, a distance of 3.8 light years. The people who colonized the planet Forseti orbiting this star at first did not realize this, they were surprised when they found a thin breathable atmosphere on its surface, the life on its surface was biologically compatible with humans, and upon closer examination they found that it was DNA based, and also geological records indicated that this world's environment was much different 10,000 years ago, someone terraformed this planet.

Hex AO BJ
Forseti:
Starport E - Frontier installation; Diameter 7 - 6,860 miles (11,038 km); Atmosphere 5 - Thin; Water surface 9 - 92%; Population 2 - 214 humans; Government 0 - No government structure; Law level 0 - No prohibitions; Tech Level 5 - Industrial age; Distance from primary 0.54 AU; Primary type M0-9 IV, V, VI; Distance of wormhole from primary 50 AU;
http://www.solstation.com/stars/barnards.htm

A population of 214 humans settled on this planet, and one of them happened to train his telescope back on the Solar System in this time period and they found this:

The ringworld was easy to see, with a bandwidth of one million miles, it was quite visible even under the glare of the Sun. Forseti orbited Barnard's star in a tidally locked by noncircular orbit, that means Forseti tracked the Sun with its rotation as it orbited, but because it orbited slower when it was further away and faster when it got closer, that means from a certain position on the planet's day/night terminator, the Sun appears to bob up and down, above and below the horizon, this is the place the humans chose to colonize because they had periods of night as well as day, during night time, an amature astronomer trained his telescope on Sol and got that picture. When word got back to Earth's government, they restricted access to this system, lest their adversaries on Sigma Draconis find out about it. the Earth is recovering from a nuclear war that occured almost 500 years ago, and some people figured that this ringworld could contain some useful technology, which they also don't want to see falling into the hands of Sigma Draconis, or the "Draconians" as they are called. Draconia around Sigma Draconis was settled by humans several centuries ago by a slower than light starship from Earth, their world is also futureward of Earth, not as much as the Ringworld, but they have a longer history since that nuclear war than the Earth has, and they have expressed an interest on conquering Earth, to prevent that from happening, the Earth government has sent a slower than light starship, powered by a black hole, to the Ringworld star system, it appears likely that this ringworld was built by humans, and they want to check it out to see if there is any technology there that they might use to fend of the Draconians and their imperial designs on the Sol System.

 

[Hakkonen]

I think the propulsion systems should be kept as real and as close to real physics as possible

...but you're fine with having a megastructure that cannot be built with any known material. OK.

 

[Reynard]

In Mongoose Traveller, real physics is reaction drive engines with high fuel needs or a solar sail up until some physics nerds hit on gravitics and exotic particle science. That's when 'real' takes a new path. Remember when the very advanced romans couldn't conceive of rocketry?

 

[Tom Kalbfus]

I think the propulsion systems should be kept as real and as close to real physics as possible

...but you're fine with having a megastructure that cannot be built with any known material. OK.

Oh, but it can be.
https://youtu.be/yk-Ivm9MhYs
A ringworld can be made with two components, a spinning ring and a stationary ring plus the star's gravity.

According to Universe Today, the surface gravity of the sun is 27.94 g, about 27.9 times stronger than the surface gravity of the Earth. The more mass an object has, the larger its gravitational pull.

Radius: 432,376 miles (695,842 km)

And gravity obeys the inverse square law with distance, convert one astronomical unit into Solar radii. An Astronomical Unit is 93,000,000 miles, divide 432,376 by this number and we get
0.0046492043 and now square it and we get 0.0000216151006 and we multiply this number by the surface gravity of the Sun which is 27.94 g and we get 0.000603925911 g, we take the reciprical of that number to get 1655.83225 and that is how many times the mass of the spinning ring the stationary ring needs to be the mass of the ringworld is 2 * 10^27 kg, the mass of the Sun is 1.989 * 10^30 kg which is approximately 2 * 10^30 kg. if we added a solar mass to the stationary ring, this would double the gravity in the system, as that ring would not only have weight under the Sun's gravity but would have gravity of its own. Doubling the Sun's gravity would get us to 0.00120785182 g, the reciprical is 827.916126, that would be how many times the mass of the ringworld, the stationary ring would be, we can increase the mass of the spinning ring to 2.41570363 * 10^27 kg. The star Sirius is 8.6 light years from the Sun, and curiously, Sirius has twice the mass of our Sun. We could use a technique called starlifting to mine out half the material of Sirius leaving just one Solar Mass behind, if we accelerated than mass to 1% of the Speed of light using the star power of Sirus to create a giant laser to push it, then it would take 860 years to transport that material to our Solar System, and use the energy of our Sun to slow it down. the next thing to do is build a hollow tube and fill it with mostly hydrogen, and use the solid portion of the Sirius material to make walls to hold it in. the stationary ring starts out in orbit around the Sun, while the ring to be spun up will push against that stationary ring to spin itself up.

 

[Hakkonen]

Two things. Well, three.

The first two are SENTENCES and PARAGRAPHS. Walls of text are not reader-friendly.

convert one astronomical unit into Solar radii. An Astronomical Unit is 93,000,000 miles, divide 432,376 by this number and we get 0.0046492043

The third is that you desperately need to check your math. To convert AU into solar radii, you divide an AU by a solar radius, not the other way around. One AU is equal to (93,000,000/432,376) = 215.09 solar radii, not (432,376/93,000,000) = 0.005 radii.

 

[Tom Kalbfus]

Two things. Well, three.

The first two are SENTENCES and PARAGRAPHS. Walls of text are not reader-friendly.

convert one astronomical unit into Solar radii. An Astronomical Unit is 93,000,000 miles, divide 432,376 by this number and we get 0.0046492043

The third is that you desperately need to check your math. To convert AU into solar radii, you divide an AU by a solar radius, not the other way around. One AU is equal to (93,000,000/432,376) = 215.09 solar radii, not (432,376/93,000,000) = 0.005 radii.

Maybe your screen is smaller than mine, to me it looks like a reasonable sized paragraph, but if your screen is smaller it looks like a wall of text, maybe you are using an I-Phone or an I-Pad to read what I typed, I have a lap top that is 18 inches wide, that means the sentences I write don't wrap around as many times on my laptop as it would in an I-Phone, sorry if that inconvenienced you. I will try to think about how this would look on a smaller screen, but sometimes my train of thought runs away with me, so I hope you under stand. What I wrote looks like a reasonably sized paragraph on the screen I wrote it on.

The reason I divided the Sun's radius by an AU is because gravity diminishes by the inverse square of the distance, and inverse square means the smaller number goes on top, so I divided the Sun's radius in miles, since I'm an American, by an astronomical unit in miles, they I squared that fraction and multiplied than number by the Sun's surface gravity, and By that means I determined the Solar gravity at 1 AU from the Sun, turns out that if I use the number Larry Niven gave for the mass of his ringworld, it is one thousandth the mass of the Sun itself, if you have a stationary ring at about the mass of the Sun, the gravitational pull between that ring and the Sun will be about equal to the centrifugal force experienced by the ringworld as it spins, this is not taking into account the tensile strength of the stationary ring, only its weight under the Sun's gravity and its own gravity at 1 AU separation.

If the stationary ring was made of carbon nanotubes, probably we can get away with some that was less massive than our Sun, I'm not sure how much mass of carbon nanotubes we will need by that is something. Turns out that there is an object in the Sirius system that is made of mostly carbon, that would be the white dwarf in the system Sirius B, Sirius B has the mass of our Sun, and it is about the size of our Earth and it is made out of carbon because it is a dead degenerate star which has fused all its hydrogen into helium and then fused that helium into carbon, and since it is not massive enough to fuse carbon into heavier elements, it has stopped at carbon and cooled down into a highly dense and hot cinder of a star, it is very difficult to mine a white dwarf of its material, unless you blow it up, and you do that by adding just enough mass to cause it to collapse into a pulsar after going supernova. Sirius B is a fairly close star to our Sun, and the effects of a nearby supernova would not be pleasant!

 

[Tom Kalbfus]

I had another idea:

Central Park in New York covers 843 acres. Central Park is located within the Manhattan borough of New York City, stretching 2 1/2 miles in length between 59th Street and 110th Street and a half-mile in width between Fifth Avenue and Central Park West.

Half a mile is more than half a kilometer. What if we were to imagine a gate forming in Central Park, a half buried circle 500 meters wide at the mid-point of Central Park in New York City, a person who steps through that ring ends up on the floor of the ringworld in the year 11,800 AD, this gate allows for two way traffic, and no one knows precisely how it works, it just appeared at midnight on January 1, 2019, and no one can quite explain it, but people can exploit it. the gate maps to this Map:

and to this map of Manhattan on the ringworld floor.

this way we can get a tech 7-8 society to explore this world using vehicles generated from the Vehicles book, and encounter all sorts of interesting things along the way.