In his book "Entering Space", Robert Zubrin devotes a third of a chapter to a concept that I find hard to beleive even by my standerds. He writes about ring-worlds on a "super-massive" scale. We're all familier with the concept. Build a ring in space and spin it. If you spin it at the write speed you make create artificial gravity equal to that of Earth. This concept has received even more attenion because of the Sci-Fi shooter game, Halo. In the game you are a super soldier that is stranded on a giant ring-world called Halo. But Zubrin's ring-world makes Halo's look very, very, very, very, very small. He proposes a ring 300 ft thick, 10,000 kms wide, and goes all the way around the sun at 1 AU. The rings "walls" would be 50 kms high to keep in the atmosherpe. The whole thing would be spun to create 1 g gravity on the surface. It would have a surface area of 9.42 trillion square kms. About the surface area of 18,440 Earths. All this, says Zubrin, would weigh only 1 Venus mass. This does have some draw-backs though. A asteroid could in theory punch a hole strait through it. Plus, how could you ever build it? Zubrin says that nanorobots could do the job. Don't ask me how. Do you think something this plain BIG could ever be built?

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I am moving this to Questions. This is not an alternative Theory.

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The Nevin books about 'Ringworld' include some discussion about this.
There are a number of problems, but the biggest has to do with the energy required move a planetary mass to it's orbit, and then to spin it up.

Personally, if I were going to have something like that built, I'd build it around a smaller star that will have a nearly constant luminosity for much longer, say an M5 red dwarf, and build the ring much closer to the star.

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I read the book "Ringworld" by Larry Niven many, many years ago but it has stuck in my memory & I occasionally remember something about it. I don´t think I have ever read it more than once but the concept is truly astounding - build a ring of material around a star at the habitable distance & you will not only increase the inhabitable area of a planet , you will also be able to take advantage of a lot more of the star´s energy as well.

I seem to remember that a huge mountain was actually found on Ringworld & they concluded that it was probably caused by the collision of an asteroid that passed clean through the ring!

I also remember there was a Startrek episode where they discover a "Dyson´s world, i.e. a ringworld elevated to its maximum expression - a sphere that totally encloses a star within itself!

At the end of Larry Niven´s book they search for the builders of Ringworld by looking for a Dyson world - & they believe they found its location!

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Interesting concept. If our race survives long enough to colonize a few stars, then this sort of thing will be inevitable. The main problem, of course is getting the raw materials to the right orbit, a daunting task indeed. With enough rockets attatched to a bunch of asteroids, it may be possible to get them there eventually. IF we are lucky there will be a system with an asteroid belt at the right orbit already.
I think construction will be much less a problem since it will likely be entirely automated and the necessary energy for contrusction would be provided by the star. I agree that the right star would be a very stable and long lived one. It also should be much smaller such that a smaller ring can be made closer to the star. To avoid orbital debris as much as possible, I would place it perpendicular to the planetary plane, an orbit that would avoid most hazardous orbiting bodies. Being able to spin the structure would not be much of a problem sine the necessaey energy would be collected from the star itself.

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The only problem with this type of world is that it is unstable. Gradually, the pull of gravity from the other planets in the system (and if there are no planets, from other stars, but on a much slower scale) will cause the ring to go off center. The closer edge will be pulled harder than the far edge and eventually it come into contact with the star (!!).

If you built a bunch of rockets on it (probably up in the billions range), you could probably counteract any inbalances.

About asteroids and comets, it shouldn't be too difficult to move them around, given that they would have already moved them around to make this. They could be used to patch things up.

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If we ever get out of this solar system, then this will happen. It'll start first with a ring around a planet. You put communication antenna on the inside and solar panels on the outside, with space for people inside the structure. Eventually, you'll clear out several star systems worth of metal to make the Ring World, and eventually a few hundred star systems to make a Dyson Sphere. I think the Dyson Sphere would have to be the most meticulously planned. Since you're enclosing a star entirely inside a sphere, you'd want to make sure it was an incredibly calm and stable star. Any major flares or coronal mass ejections would make for a bad day for the residents on the interior of the sphere.

And I like the idea of making the Ring World perpendicular to the orbital plane of the star, but would that work? If you built it perpendicular to the star's spin axis, would there be any gravitational shear that would throw the orbit off?

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if u like the ringworld idea then you'll love the dyson sphere.
take all the material in a solar system and make shell around the star.
google dyson sphere for more detailed info.

Ringworlds are a nifty idea, but I don't think they'll ever be made. They're simply not practical.

If I remember right, the amount of material necessary to construct one of these would be the equivalent to one or two of our solar systems. The energy required to gather and process that material, manufacture parts and move them into place would be staggering.

A Dyson sphere is even worse.

The only justification I can come up with for such a massive project would be if we were unable to find any other habitable worlds within our galaxy, and Earth was no longer viable for humanity to remain on.

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I really like this topic and I would like to add my take on it.

First of all is this possible? Absplutly.......

building the architectorial struture to withstand the gravitational pull from the star is theoretically possible.

finding the material to build such an object.. easy the one thing there is not a shortage of in this universe is matter. There is alot of it and too much for the human brain to comprehend.

The thing is this such a structure is not proctical for colonizing for normal life and use. The gamma radiation comming from even a K or M type star (the most stable, long lasting, and most predictable types of star) would be too much at the distance 1,2,4,5,6 au's. The only practical use for such an object is for energy resource. If we build on of these things is to put a buncn of solar panels around it and gather energy for free.

Reallistically if we want to build one of these things to live and create a civilization we would build it aruond a so called "failed star" or "super planet"

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You arent thinking like a type III civilian. With the energy of a sun at our disposal who knows what sort or technology we would have.

Its funny, we found the next step towards this with nuclear reactors but unfortunately had little time to master it before everyone got to scared. Man would it suck if we this is delay too long and we end up gettin smashed by an oversized rock-popsicle.

Here is my own ringworld, Ouaddai;
http://www.orionsarm.com/worlds/Ouaddai.html

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The Millennial Project by Marshall Savage is an entertaining though far fetched speculation (well documented) about how to collonize the galaxy in 1000 years. Recommended for the immagination.

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Is there a link to this? it sounds fascinating

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I like your image of the ringworld, Ouaddai, eburacum45. I also went along & visited the website you posted a link to. It looks like a very well thought out community & I think I shall probably be returning &, who knows, I may contribute something!

Did you make up the image yourself?

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In the game freelancer there is a massive sphere world built around a star. It looks pretty cool.


As for the problem with astroids and stuff, If we were advanced enough to build somthing like this, then i'm sure getting rid of astroids would be easy. The ring could be lined with somekind of missle intercept system which could blow up any astroids.

Also there would also be millions of ships leftover which were used to moved building materials, they could be used move astroids out of the way.

We would have enough resorces in our solar system to make one, or even more then one ring world, which could rotate around diffrent axies. That would solve our overpopulation problems for ever.

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You say that the gamma radiation would be too much. But Earth is only 1AU away and it deals with the radation allright, I'm sure some kind of shield could be built to prevent dangrous rays getting in.

But building a ring around a star to expend way to much energy.

Much more releastic would be to build a ring around a planet, not around Earth because it would mess up all the tides, around Mars would be a good idea, and resorces could be taken from the astroid field.

I think this will have to happen in the distant future, Earth already has two many people for it reasorces, and the only other planet suitible of life is Mars, At the rate in which the population is growing on Earth, it wouldn't take that long for Mars to fill up. Then we need more room.

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One problem that pops up is the temperature difference between the inside of the ring compared to the outside of the ring..

Secondly, I picture tidal forces breaking it up and comets having fun bashing into it.

Then, we calculate the center of mass that the star and ring world must rotate about and we get quite a wobble. Ring world turns into lasso world..

Solar flares would really have a ball busting it up..Almost like a rifleperson at a shooting gallery.

But...why knock it...After all, maybe that is how the solar system formed. The Sun,
in its early stages, may have sent out strong gravitational waves into surrounding
planetesimals that could have caused certain materials to settle at precise distances from the star, forming rings like Saturn has.

They would have broken up quickly due to some reasons above and probably a few more that Tim Thompson could add...

This one isn't quite as corny as the one I cooked up years ago.

I had Uranus being the first planet to form, holding bigger rings than it has now.
As its ring system started to collapse, the rotation of the planet would throw material toward the Sun and away from the Sun during 2 seasons of the year,
when the poles are parallel to the star..Comets would get flung in both directions,
starting them into the habits they now possess. Matter dragged inbound toward the star would also help form the inner planets with the gaseous ones forming near Uranus...

Then, during the other two seasons I had Uranus tossing the rest out into the Kuiper belt, giving it the mass it now has, while maintaining a ring around the solar system...

I'm almost dead sure this doesn't hold water but it's neat to bring up things like this anyway.

blueshift

I like your image of the ringworld, Ouaddai, eburacum45. I also went along & visited the website you posted a link to. It looks like a very well thought out community & I think I shall probably be returning &, who knows, I may contribute something!

Did you make up the image yourself? [/b][/quote]
Yes, I did, actually; it uses a variety of techniques, including Microsoft Word!

but I hope to do better soon, and you might even be able to land on the ring eventually.

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Zubrin needs to get the systems for his habitat test working properly before he starts talking about projects of this size.

Also, considering how no one(so far) in the Forum(per my suggestions)has switched even a single incandescent light bulb out to an energy-efficient compact flourescent light bulb, and how the 3rd World Telescope Project is languishing at $17 in funding, I doubt that anything of this magnitude will ever happen.

However, in the spirit of fun...re-The asteroids will probably be needed for building material for the ring anyway, so that will solve 2 problems at once...remember the words "dual-use" folks!

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