Ringworld (CT type)

[Garyius2003]

Even if the Hivers make everyone from the horses to the Sols support the mission, we are looking at 20-40 years to make the walls and 100-500 years for the first hab zone, expanding every 50-100 years from there.

A huge huge amount of property, but still...

 

[rancke]

Here's a couple of ideas for smaller ringworlds. Note that I have no idea if either of them would work nor what sort of ringworld dimensions that would result.

1) A ringworld with an artificial miniature sun in the middle. The Ancients slapped together a bunch of hydrogen and set it on fire. Would such a construct (the sun, not the ringworld) work and last for several million years?

2) A ringworld around a brown dwarf. Would a brown dwarf provide the necessary energy?

What I like about the second version is that you could drop such a ringworld in any empty hex in Charted Space and it could have remained undetected until the Classic Era (and the PCs) came along.


Hans

 

[Xerxeskingofking]

Here's a couple of ideas for smaller ringworlds. Note that I have no idea if either of them would work nor what sort of ringworld dimensions that would result.

1) A ringworld with an artificial miniature sun in the middle. The Ancients slapped together a bunch of hydrogen and set it on fire. Would such a construct (the sun, not the ringworld) work and last for several million years?

2) A ringworld around a brown dwarf. Would a brown dwarf provide the necessary energy?

What I like about the second version is that you could drop such a ringworld in any empty hex in Charted Space and it could have remained undetected until the Classic Era (and the PCs) came along.

Hans

I'm not a astrophysicist, but i think it might work. Close enough to workable for most sci-fi, at any rate.

The artifical star would need to be a full sized star in order to substain fusion, unless some form of ancient S.A.T* is constantly artfically increasing the pressure to keep the reaction going (remeber, the easist way for humans to create a fusion reaction is with a nuclear bomb.)
it also says:

likewise, although an object with mass above approximately 0.013 solar masses will be able to fuse deuterium for a time, this source of energy will be exhausted in approximately 10^6 to 10^8 years

our sun is roughly 1000 times the size of jupiter, so a stellar mass of about 150-200 jupiter masses would do the trick.


A Brown dwarf would make a suitable anchor for the ring, and in my quick reading on wiki, they can undergo lithium and Deuterium fusion, which means the could give off a at least some heat and light. at any rate, they give off enough that we've see one of them from 400 Parsecs away.

apprantly, current models and obervations suggest about 1 brown dwarf pre 6 full stars.

*S.A.T. = Sufficently Advanced Techology, in the Clarks Third Law sense.

 

[aramis]

And there is nothing in the A12 entry (at least in what Aramis quoted) that says there are no side walls (or even just sections missing).

And even if there weren't, there are many worlds in the Imperium with little or no atmosphere but a large population.

You could build a lot of large domed habitats with extensive hydroculture gardens for food, etc... which won't require nearly as much in the way of resources as making the whole ringworld a fully functional habitat.

It does say it lacks atmosphere - you'd be building as if in vacuum no matter whether there are side walls or not.

To cover the bloody thing to a measurable pressure, you'd be bringing in a Uranus sized body's worth of atmosphere.

 

[rancke]

It does say it lacks atmosphere - you'd be building as if in vacuum no matter whether there are side walls or not.

To cover the bloody thing to a measurable pressure, you'd be bringing in a Uranus sized body's worth of atmosphere.

Immature clone's play for an Ancient, but not feasable at TL15.


Hans

 

[aramis]

Here's a couple of ideas for smaller ringworlds. Note that I have no idea if either of them would work nor what sort of ringworld dimensions that would result.

1) A ringworld with an artificial miniature sun in the middle. The Ancients slapped together a bunch of hydrogen and set it on fire. Would such a construct (the sun, not the ringworld) work and last for several million years?

2) A ringworld around a brown dwarf. Would a brown dwarf provide the necessary energy?

What I like about the second ve)rsion is that you could drop such a ringworld in any empty hex in Charted Space and it could have remained undetected until the Classic Era (and the PCs) came along.


Hans

Minimum for proper ignition without technological intervention is about 75 Jupiter Masses (or about 0.075 Solar Masses). For deuterium-only, about 13 (according to Fraser Cain on Universe Today).

Maintaining an artificially started reaction should be doable at somewhat less on both scores... but it's still going to be in the double-digit Jupiter masses And then, you have to have the ignition start deep enough to not simply blow a shell off - which would be a trick all its own.

 

[rancke]

Maintaining an artificially started reaction should be doable at somewhat less on both scores... but it's still going to be in the double-digit Jupiter masses And then, you have to have the ignition start deep enough to not simply blow a shell off - which would be a trick all its own.

I'm going to assume that the Ancients did it, so that part is just a handwave. What's needed is an artificial sun that will burn without Ancient supervision for several million years once ignited. And I assume that double digit Jupiter masses will still be a lot smaller than even the smallest natural star. I've no idea how much smaller, though. What would be the dimensions of such a ringworld?


Hans

 

[Blue Ghost]

Some thoughts;

One of my biggest beefs with Ringworld or like concepts is getting rid of heat. The reason life works on earth is because the earth spins. This function does two things; it turns the hot side away from the heat source so that it can cool down and dump heat into space, and also generates the magnetic field that protects us from other radiation.

How do you do that with a ringworld?

Just me.

 

[inexorabletash]

I think it's been shown that a Ringworld is inferior to a Culture-style Orbital. Orbitals give you a huge surface are without requiring as much material, unobtabium, or active stabilization.

You'd only build a Ringworld if you were bored, crazy, or trying to solve those problems for lulz.

 

[aramis]

I'm going to assume that the Ancients did it, so that part is just a handwave. What's needed is an artificial sun that will burn without Ancient supervision for several million years once ignited. And I assume that double digit Jupiter masses will still be a lot smaller than even the smallest natural star. I've no idea how much smaller, though. What would be the dimensions of such a ringworld?


Hans

No, it won't. 75 Jupiter masses is the lowest that can sustain long term protium fusion. I've seen someone do the numbers for jupiter - it will flashover, once, taking a decade, then fizzle, if it will even get that much. Literally, the fusion shockwave will blow the fuel away, because the energy release is fast enough that it increases the core pressure too much. Between 13 and 75, you've got deuterium fusing, but not protium.

You might be able to get a dim purple glow below 13 Jupiter masses (even as low as 1 Jupiter mass, if young enough)... but not useful sustained fusion fast enough to provide visible light as we understand it long term.

Keep in mind that Jupiter is still radiating heat from its own formation.

 

[Blue Ghost]

Some quick notes, when we discussed ringworlds back in 2004 or thereabouts (and before then), I did have plans to create a sourcebook for one, and a few other materials.

But, another poster was fairly mercenary about the content and concepts I was proposing. Oh well. Then HALO came out, and the rest is history.

My short reply on Ringworlds is that regardless of our understanding of science and engineering, they are doable in Traveller, but you have to do the handwave thing as per the rules for jump drive, hyperspace, grav science and a host of other things. I know that's what I had planned, and I had no compunction about writing up a Ringworld or two or three or more.

The feasability of one in the canon 3I or its neighbors, I think, is up for debate. If you can build an arcology or network thereof, gravitic palaces, starships et al, then I think Ringworlds aren't too far off regardless of the rules. Just employ a crap-load of robots to get to work on the thing, and use every rock you come across for material. The inner hot worlds and mini gas giants in the outer orbits are perfect for this kind of thing. Rogue worlds can provide material too.

But, like the other guy said, what exactly are you trying to achieve with the construct? To me an orbital ring makes sense for easy access to commerce and transportation of goods. But what good is a Ringworld? I'm sure there's lots of reasons....someone list them...I need to sleep.

 

[whulorigan]

And I assume that double digit Jupiter masses will still be a lot smaller than even the smallest natural star. I've no idea how much smaller, though.

Brown Dwarfs are roughly Jupiter-size to some what larger than Jupiter over their mass-range (~13-75 M_J), but don't tend to increase in diameter significantly with increasing mass. This is because increasing mass produces higher gravity that in turn compresses the material.

The Gas Giant Table on p.437 of the T5 Core Book notes that all Brown Dwarfs are Size=Q (60,000 miles diameter), though this is smaller than Jupiter. I am not sure if this is an errata item or not.

 

[whulorigan]

One of my biggest beefs with Ringworld or like concepts is getting rid of heat. The reason life works on earth is because the earth spins. This function does two things; it turns the hot side away from the heat source so that it can cool down and dump heat into space, and also generates the magnetic field that protects us from other radiation.

How do you do that with a ringworld?

Niven's Ringworld had an inner-ring of intermittent "shadow-squares" that orbited at a slightly different rotation rate in order to produce artificial periods of day and night on the Ringworld surface, so radiation could occur somewhat during those periods. But also remember that the entire outer-surface of a ringworld is always pointed away from the central star, and thus could be used as a radiator surface.

Also, could the temperature gradient between the inner and outer surface be used to produce power and/or power a system that generates a magnetic field?

I also seem to recall that Niven's idea was that the Scrith-material that the ring was made from was also a superconducting material that produced a magnetic field for the ring as it rotated.

 

[rancke]

The feasability of one in the canon 3I or its neighbors, I think, is up for debate. If you can build an arcology or network thereof, gravitic palaces, starships et al, then I think Ringworlds aren't too far off regardless of the rules. Just employ a crap-load of robots to get to work on the thing, and use every rock you come across for material. The inner hot worlds and mini gas giants in the outer orbits are perfect for this kind of thing. Rogue worlds can provide material too.

A crap-load of robots would cost a butt-load of money. The Traveller paradigm does not accomodate von Neumann machines (not at TL15 anyway). So each and every robot has to be bought and paid for, gets worn out and has to be repaired occasionally and eventually replaced. Building a ringworld at TL15 would cost a LOT. Far more than practical. Or so I suspect. I admit I can't prove it.


Hans

 

[Vladika]

A crap-load of robots would cost a butt-load of money. The Traveller paradigm does not accomodate von Neumann machines (not at TL15 anyway). So each and every robot has to be bought and paid for, gets worn out and has to be repaired occasionally and eventually replaced. Building a ringworld at TL15 would cost a LOT. Far more than practical. Or so I suspect. I admit I can't prove it.


Hans

Hans, this one I don't think you have to prove. It's so self evident as to be inarguable.

That being said... watch the arguing begin.

 

[aramis]

A crap-load of robots would cost a butt-load of money. The Traveller paradigm does not accomodate von Neumann machines (not at TL15 anyway). So each and every robot has to be bought and paid for, gets worn out and has to be repaired occasionally and eventually replaced. Building a ringworld at TL15 would cost a LOT. Far more than practical. Or so I suspect. I admit I can't prove it.


Hans

It's unlikely at TL15 - we know the properties of superdense well enough to know it's not scrith.

We also know that most ancients constructions are TL 17-22. We also know that the ancients used extensive automation. While not technically Von Neuman gray goo , one can build autofactories that produce robots and parts for more autofactories to build the workforce needed.

Also, we know at least one Ancient is still active - the Droyne are, far better than the Pak of Niven, able to plan and execute long term projects.

 

[Blue Ghost]

*checks flame thrower, tops off with napalm*

I think it's a case of Your Traveller Universe May Vary. I don't think hemming and hawing over how the construct was built in terms of the reality of the game's Official Universe is pertinent to the notion of including one or more in the 3I or elsewhere. Construction techniques with gravitics, to my mind, makes lots of things possible that could never be accomplished with hammer and nails.

I think the only limitation is finding enough matter to make your object feasible. You might have to plunder a couple of other solar systems to get the ringworld you envision, but using gravitics, I think, would just make constructing one of these things a matter of laying down survey points (in space), fabricating pieces with the proper shape or bend, and then dropping or moving them into position.

Personally, I don't see the big deal in making one. I think mister Miller and others have stated that a world's/system's typical TL maybe X, but it maybe X + Y in certain areas, and X - Z in others, allowing some leaps in science in technology, while lagging in others.

Meh....I'm going to write one up anyway like I should have ten years ago when we discussed this topic.

 

[aramis]

*checks flame thrower, tops off with napalm*

I think it's a case of Your Traveller Universe May Vary. I don't think hemming and hawing over how the construct was built in terms of the reality of the game's Official Universe is pertinent to the notion of including one or more in the 3I or elsewhere. Construction techniques with gravitics, to my mind, makes lots of things possible that could never be accomplished with hammer and nails.

I think the only limitation is finding enough matter to make your object feasible. You might have to plunder a couple of other solar systems to get the ringworld you envision, but using gravitics, I think, would just make constructing one of these things a matter of laying down survey points (in space), fabricating pieces with the proper shape or bend, and then dropping or moving them into position.

Personally, I don't see the big deal in making one. I think mister Miller and others have stated that a world's/system's typical TL maybe X, but it maybe X + Y in certain areas, and X - Z in others, allowing some leaps in science in technology, while lagging in others.

Meh....I'm going to write one up anyway like I should have ten years ago when we discussed this topic.

A couple? At least three systems with as much rock as our own for a reasonable starting point - a 0.1km thick ring of the dimensions in A12 (FAR less thickness than Niven's ringworld) has at least 10% the mass of Jupiter. Earth, the largest rocky body in the system, is about 1% of Jupiter's mass - as is venus; Mars, Mercury, and the asteroid belt together might comprise another earth mass. The KBO's and satellites together might add another half-earth mass. If the mass ratios between gas and rock are similar in other systems, then it might only be two with brown dwarfs and lots of rocky moons as big as mars.

And that's without walls.

 

[Blue Ghost]

*I should be sleeping*

What're you trying to say? :CoW:

 

[aramis]

*I should be sleeping*

What're you trying to say? :CoW:

Harvesting enough metals to make it is likely to be dozens of systems.

Or is going to be conversion of matter on an atomic level at mindboggling scales.

Or both.