Halo Science - Ringworlds and Plasma Weapons

The book Halo Effect is an intriguing title that takes a look Bungie's best-selling Halo titles from a number of different angles. Each chapter includes coverage of specific elements; included are descriptions of pro events, a bit on the development process, and the making of the Red vs. Blue series. One of the most interesting chapters takes a look at the science behind the Halo world, talking about the physics and logic behind ringworlds and the hi-tech weaponry seen in the game. Thanks in part to a mini-review of the book on the GameSetWatch site, Gamasutra has been allowed to reprint the entire 'science of Halo' chapter on their website. "A 5,000 kilometer radius would yield a circumference of roughly 31,400 kilometers. If we assume a width-to-radius ratio similar to that of Niven's Ringworld, they would be approximately 5.37 kilometers wide. They are significantly wider, though, at 320 kilometers. The Halos, then, would have a surface area of 10 million square kilometers - slightly larger than the surface area of Canada, and approximately 2 percent of the surface area of Earth. Of course, since we know that there are lakes, seas, and rivers on the Halos, the livable surface area would be fractionally less." Update: 05/02 18:30 GMT by Z : The initial version of the article posted was from pre-production and contained some errors. They've been fixed in the article and now here in the post as well.

decimal point

[PresidentEnder]

I assume that there is a missing decimal point in the summary, since those figures give a much larger surface area.

Re:

[Chris Burke]

Has to be, since I'm pretty sure Niven's ring didn't have a width/radius ratio of 10, since that would have made the ringworld 930 million miles wide, a veritable ringtube where the ends would be frozen and uninhabitable. I don't have the book handy, but I'm pretty sure the ring was actually fairly narrow, perhaps only a few thousand miles wide on a ring over five hundred million miles around.

Re:

[ATestR]

Niven's Ringworld was 1 million km wide (although the units may have been miles). Assuming that the units were in km, to have the same proportions as the Ringworld, the Halo world would have to be approximately 5/150 times this, or 33,333 km wide.

Re:decimal point

[gobbo]

Has to be, since I'm pretty sure Niven's ring didn't have a width/radius ratio of 10, since that would have made the ringworld 930 million miles wide, a veritable ringtube where the ends would be frozen and uninhabitable. I don't have the book handy, but I'm pretty sure the ring was actually fairly narrow, perhaps only a few thousand miles wide on a ring over five hundred million miles around.

Niven's Ringworld is one million miles across the ribbon, the rim walls holding in the atmosphere are 1000 miles high, and its circumference is 600 million miles around. For those who use a more sensible and thus cowardly* base 10 measurement system: 1,609,344 km wide, rim walls 1,609 km high, and 965,606,400 km in circumference. That yields a radius (AU) of 153,681,031 km. The radius/width ratio is thus about 154:1, so your instincts are correct, even if the calculation is a bit off.

Added bonus: the surface area works out to 1.6×10^15 sq.km--about 3 million Earths; wrap your head around that! Halo's 10,000 km diameter is relatively tiny.

(* Profuse apologies: impugning the valour of anything French, including metrics, on american-run sites is, seemingly, de rigueur.)

Re:

[ReverendLoki]

(* Profuse apologies: impugning the valour of anything French, including metrics, on american-run sites is, seemingly, de rigueur.)

Actually, it's more directed towards anything uniquely, or at least characteristically French. Since the metric system is much more widely used than in just France. So, Metric gets a pass on being classified as one of those "French things" to be mocked. No, we mock the metric system as one of those "European things", which operates on a different scale altogether - fewer

Re:

[Trails]

Canada uses it too! Does this mean it gets mocked less? ... why is everyone laughing?

Re:

[Blackhalo]

"Canada uses it too! Does this mean it gets mocked less? ... why is everyone laughing?" Canadians are clearly worthy of quality mockery in thier own right, with the added incentive of the French Canadians. Plus since Canada is in North America they are literaly Americans resulting in mockery incentive that is off scale.

Mod Parent Up, Please

[MikeyTheK]

1) You didn't include a disclaimer, so you now owe me a new monitor and keyboard. "cheese-eating surrender-monkey" is priceless. (golfclap/)

2) The signature is great, too. Well done. I have no mod points today or I'd give you one. The only question would be for funny or underrated. Watch - now I'll have them for the next four days running.

Re:

[MikeyTheK]

Ugh. I hate it when Slashdot eats fake tags. Let's try the first one again with parens instead of brackets: 1) You didn't include a disclaimer (WARNING: Swallow liquid contents in mouth before continuing to read/), so you now owe me a new monitor and keyboard. "cheese-eating surrender-monkey" is priceless. (golfclap/)

Re:

[gobbo]

Actually, it's more directed towards anything uniquely, or at least characteristically French. Since the metric system is much more widely used than in just France. So, Metric gets a pass on being classified as one of those "French things" to be mocked. No, we mock the metric system as one of those "European things", which operates on a different scale altogether - fewer cheese-eating surrender-monkey references, for one.

Ah well, wit is wasted on the young, and America chooses to be perennially young. I was referring, of course, to the origins [colostate.edu] of the metric system.

Re:

[ReverendLoki]

Ah well, wit is wasted on the young, and America chooses to be perennially young. I was referring, of course, to the origins of the metric system.

Actually, I was quite aware of it. In fact, I was also considering the use of the French language as another example akin to the metric system (really, it isn't the language that gets mocked, but rather the particular dialect one finds in France). I was all set to go on about how the French Canadians and the Cajuns down south both get mocked for their language

Re:

[Hal_Porter]

Ah well, wit is wasted on the young, and America chooses to be perennially young.

You know when making Francophile arguments to les neocons internets it's de rigueur to describe American culture as jejeune. The English phrase "perennially young" lacks a certain je ne sais quois.

Re:

[gobbo]

bwahaha! touché!

Re:Ringtube?!?

[Trails]

Ringtube!?! No, since you've dropped the functional component of the word (i.e. "world", what purpose it serves), and compounded two shape descriptors, ring and tube.

The correct term is Tubeworld. Despite the environmental problems you point out, this is clearly superior to aringworld, since it would be its own internet.

Re:

[NeilTheStupidHead]

But with only one tube, the bandwidth would be terrible.

Re:

[Trails]

Dude, it's 2 AU's across! That's a LOT of pr0n.

Re:

[The Great Pretender]

Tubeworld? Is this where the Ambiguously Gay Duo come from?

Re:

[Indiana Joe]

"The correct term is Tubeworld. Despite the environmental problems you point out, this is clearly superior to a ringworld, since it would be its own internet."

Talk about a fat pipe...

Re:

[RagnarokGod]

would not the correct term be a tokenring world?

Re:

[LiquidCoooled]

I thought the same, a circumference of 31,400 kilometers and a width of approximately 53,700 kilometers.
That would be a fucking thick tube.

The whole thing has a radius of about 5000km.

Maybe Ted Stevens was right?

Re:decimal point

[bhima]

From the back of Ringworld (1970 printing)

A ring 93 million miles in radius (on earth obit)
600 million miles long
One million miles wide
thickness of of about 1000 meters
walls on the edge 1000 miles high

Rotation on axis 770 miles per second

But I'm sure those or just generalities

Re:

[AvitarX]

"Rotation on axis 770 miles per second"

That doesn't even make sense.

Re:

[Silverlancer]

Yes it does. Its the speed needed to keep 1G of "gravity" from the centripetal force.

Re:

[AvitarX]

Maybe I am too stupid to understand, but wouldn't rotation on axis be measured as RPM, or deg/sec or rad/sec?

In fact the linear speed when on the actual axis would be 0 miles per second.

I assume 770 miles/sec is the linear speed when on the ring 93 million miles away from the axis.

I am eager to be corrected on this though.

Re:

[gstoddart]

I assume that there is a missing decimal point in the summary, since those figures give a much larger surface area.

Indeed. That, and a radius of 5000kms from our Sun would put you squarely in an area of space you wouldn't want to spend much time in.

The ringworld in Niven's book was utterly huge.

Cheers

Re:decimal point

[toolie]

That, and a radius of 5000kms from our Sun would put you squarely in an area of space you wouldn't want to spend much time in.

Newark?

Re:

[gstoddart]

That, and a radius of 5000kms from our Sun would put you squarely in an area of space you wouldn't want to spend much time in.

Newark?

Well, I've only ever been in the airport, but I think you're probably correct from what I saw.

Cheers

Re:

[Fulcrum of Evil]

No it wouldn't - you don't have to have this thing orbitting the sun on axis. It's much easier to build them in orbit around a planet the right distance out, and much easier to move them around afterwards. Banks got this right.

Bad Calculations

[rherbert]

"A 5,000 kilometer radius would yield a circumference of roughly 31,400 kilometers. If we assume a width-to-radius ratio similar to that of Niven's ringworld, we get a width of approximately 53,700 kilometers. The Halos, then, would have a surface area of 1.68 million square kilometers."

A width of 53k kilometers and a radius of 5k would be a very long cylinder. Given the other numbers, 1,680,000 km^2 / 31,400 km gives a width of 53.5 km, which is much more reasonable and ring-shaped.

Go to the original

[linzeal]

Why bother with the mediocre writing of game novel hacks when you can go straight to Niven [amazon.com]?

Re:

[Blakey Rat]

The Halo is not the only science fiction element in the Halo universe, you know. It's just the one it's named after. It also has a pretty unique AI concept (pioneered from the Marathon games, I believe) as well as an interesting alien civilization consisting of different races with a strange and pretty complex social dynamic but all seem to work (more or less) together despite that. Then there's the Flood, which is some sort of super-evolved virus or bacteria.

If you read the novels, they also shove in a bun

Re:Go to the original

[locokamil]

Agreed. I read the novels before I played the games, and I was surprised by how convincing the sci-fi actually was. Characterization was off, but the science was good, and all four books described an appealing future with _relatable_ human technologies, i.e. the technology was advanced, but not so far advanced that I found it implausible.

GP is a tool, make no mistake. The Halo books are solid sci-fi in their own right.

Re:

[Ryan Amos]

Marathon was a great series. You were essentially the pawn in a war between 3 competing AIs. The worst part of the games was the inability to jump. They released level editors that let you fuck with the levels in any way you wanted though so it was all good.

And the dual auto-reloading sawed off shotguns in Marathon 2 have got to be the most kick-ass weapons I've ever played with. They had a great rhythm to them while also having the ability to shred armies of enemies if you got them in a hallway.

Re:

[julesh]

Because while Niven's Ringworld is widely considered as an impossible structure due to the extraordinary structural strength requirements it places on his "scrith", something somewhat Halo-like could actually be built by a civilization not incalculably more advanced than our own. Therefore, its details make a more interesting thought exercise than Ringworld's do.

but...

[Archades54]

the inhabitants would be angsty aggressive teenagers, so we need to tugboat the ring into a the sun.

maybe the pale folk would finally see some sun

Sorry Niven;

[B5_geek]

The Ringworld is unstable!

Sorry I just couldn't resist.

Ringworld is simply a must-read for anybody who considers themselves a geek. Thank God it won't ever be made into a movie.

Re:

[irby0]

Snippet from http://www.mania.com/41212.html [mania.com] :
"Based on Larry Niven's RINGWORLD series of novels, a four-hour mini-series is in development. In the future four explorers crash on an artificial structure in deep space, a mammoth ring that circles a distant star."

I've been waiting for years- I guess we'll see if it ever comes to fruition.

Re:

[redtape]

From the article on the site:
Date: Tuesday, April 6, 2004

So, they obviously are taking their time about it...

Iain Banks Orbitals

[argent]

Halo is more like Iain Banks "Orbitals" than Niven's Ringworld.

I haven't played Halo, but from what I've seen on the net I suspect the GCU Grey Area might be poking around there some time...

Re:

[simm1701]

I rather like the character of "Meatfucker" - and the Culture novel universe in general - its certainly a future I can relate to and would be very happy living in - without it being too shiny happy optimistic about the way things will turn out

Re:

[argent]

its certainly a future I can relate to and would be very happy living in - without it being too shiny happy optimistic about the way things will turn out

You quite sure it's a future you'd be happy living in? Have you read State of the Art? :)

Re:

[simm1701]

Yep - its a completely fucked up universe but I think it would suit me.

I'll freely admit I'd certainly prefer being part of the Culture or the Ulterior - but within those parts I could be quite content

Re:

[argent]

Yep - its a completely fucked up universe but I think it would suit me.

Ah, you haven't read The State of the Art then.

The Culture novels are not set in the future.

Re:

[Fulcrum of Evil]

This should be clear to anyone who's read Consider Phlebas. Also note that, in interviews, Banks has said that the Culture isn't necessarily Human (almost certainly not) and that Humans may not be capable of the change.

Re:

[simm1701]

Ah now I get your reference - true that it is set now but they would just ignore this planet as unbeleivably strange and primitive - though thats a fairly standard twist for science fiction in general

Re:

[argent]

Earth isn't being ignored. It is the untouched control in the Culture's experiment.

Yeh, bastards... why the hell did they have to pick us as the control? It's the opposite of the anthropic principle, anyone would think it was a cosmic plot device to explain why we haven't been...

Oh, yeh... :)

Re:

[szyzyg]

There are quite a few links between Iain M Banks work and the Halo series - and I absolutely recommend anyone who's not read his work to check it out. Larry Niven was certainly first with the ringworld design, but the orbitals are more directly related to the game environment.

Someone has put together a nice list of similarities between the games and the books.

http://marathon.bungie.org/story/halo_culture.html [bungie.org]

Re:

[argent]

Oooh, VERY interesting.

The Halo ships seem a bit boring compared to the Culture ones, though.

Re:

[julesh]

Have to ask: are you the 'szyzyg' I used to know on mono?

Re:

[orkysoft]

But 1.68 million square kilometers? That's a toy compared to an Orbital! At least, that's what Hub says...

Ringworlds have a lot of problems

[SirBruce]

Unfortunately, there are numerous technical problems that make Ringworlds problematic, as Niven tried to address in later books. The Ring requires active stabilization, day and night cycles can only be crudely simulated, etc. Perhaps the biggest problem is that the structural material itself would have to have the tensile strength of the strong nuclear force just to hold together...

Dyson Spheres actually make a lot more sense than Ringworlds. Any civilization capable of making a Ringworld would most likely be able to make a Dyson Sphere.

Re:

[Anonymous Coward]

A solid Dyson sphere is just as unstable as a ring, for the exact same reason. Day and night cycles are even more difficult to simulate. And the structural issues are just as insurmountable.

Probably the answer is to abandon a solid surface, but that works as well for a ring as a sphere.

Re:

[SirBruce]

I didn't realize a dyson sphere would be unstable, but you're right. As for a shell, I think the structural issues are not as bad as for a ring, but it's been a long time since we did the math in physics class...

Re:Ringworlds have a lot of problems

[HiThere]

Dyson spheres are also unstable, though not drastically so. And, practically speaking, you need a pair of them, concentric (you hold the atmosphere between them. There really WOULD be pillars holding up the sky! And etherial spheres (well, at least one of them). Keeping the sun in the center, however, looks to be a bit tricky, but fortunately the net gravitational instability should be quite small even if the sun is slightly off center (you can't assume that mass is actually symmetrically distributed, only approximately).

Note that as you don't spin a Dyson Sphere, net gravity is very low. About half that of the Sun's from the distance of the Earth. This makes ponds, lakes & seas possible (if not probable, and probably temporary), but quite dangerous. Rivers, however, are not going to occur.

Re:

[CogDissident]

Why couldn't you spin a dyson sphere?

You could stabilize it with a large number of low yeild thrusters placed on the outside of the sphere, keeping the sun at the center without needing to have any physical contact with it. These thrusters could also be used to spin the sphere, causing a centrifugal force that pushes outward from the sun, needing no cealing whatsoever (assuming you were at least earth's distance from the sun away, at all points), because things would fall away from the central gravity of

Re:

[eht]

Then you end up with all practicality a ringworld as you wouldn't be able to do anything at the poles. So get rid of that wasted space and just make a ring. A sphere would either require two layers and have very low simulated gravity, or some kind of gravity generation device, which if it ever failed, could be disastrous, and many localized ones over something the size of a Dyson sphere would be a nightmare to maintain, along with a need to make portals if you actually wanted to leave the thing.

Re:Ringworlds have a lot of problems

[ip_vjl]

When I read Ringworld, I wondered why you wouldn't build something that combined both a ringworld and a Dyson sphere. Let's say the ringworld followed Niven's dimensions. At 1 million miles wide, it only occupies about 1% of the 'latitude' of the orbital sphere. All the solar energy directed elsewhere is wasted.

It seems it would be good to build a smaller sphere that can collect this energy. If you built it at an inner orbit (like Mercury's orbital distance) you wouldn't need as much material. You would leave out a section of the middle that corresponds to the location of the 'ring plane' to allow the energy there to make its way to the ring. Both halves of the sphere could still be connected, but instead of solid sphere, it would be alternating solid/empty to provide the function of the shadow squares. You may want to perforate it in other areas as well to allow solar pressure to escape.

Exactly what materials you'd use, I don't know ... but if you have the resources to build the ringworld to begin with, this shouldn't be a stretch.

Re:

[LiquidCoooled]

assuming the Star chosen is approximately similar to our Sun, if you produce a ring much closer everything would fry.

Re:

[ip_vjl]

The ring wouldn't be closer. The ring would be like Niven's, out at Earth distance.

The *sphere* would be at a much closer distance to the sun so that you wouldn't need as much material to construct it. Its only purpose would be to collect energy. You would just leave the center with 'cutout' sections to allow energy to continue to travel out to the ring at its further distance.

Re:

[Headw1nd]

It might be a better idea to choose a smaller star than the sun, firstly to save on materials, secondly to have lower spin rate, and thirdly to have as long lasting a star as possible. I mean after all, if you're going to build a ringworld, you want to build it to last.

Re:

[RagnarokGod]

and allowing for keeping everyone happy in the "habitable" - life-supporting temperature - liquid water zone?

Re:

[Grishnakh]

Maybe I'm missing something, but why would a sphere have low gravity? Couldn't you just add mass to the shell to increase gravity?

As for the poles, wouldn't it be better to keep those covered so that you can harness the solar power (rather than using them for habitats)? After all, the definition of a type II civilization is that they're able to use the entire power output of a star. You can't do that if you let most of the solar radiation escape.

Re:

[cswiger]

Maybe I'm missing something, but why would a sphere have low gravity?
Couldn't you just add mass to the shell to increase gravity?

Oddly enough, no. :-)

Extra mass farther away from you than the center of gravity doesn't count-- if you dug a very deep tunnel towards the center of the earth, you'd find yourself weighing less the deeper you got.

Re:

[Grishnakh]

Ok, I'm still confused. I've read a little about Dyson Spheres and ringworlds, and I thought that in a full-size Dyson sphere, the gravity was generated simply by the mass of the sphere itself. The mass wouldn't be farther from the center of gravity; a human standing on the inside surface would be 1 AU from the star inside (presumably the size of our Sun), and the sphere itself would be quite thick, so that at any point on the interior of the sphere, there would be a large amount of mass underneath a pers

Re:

[king-manic]

Gravity is affected by mass linearly but radius exponentially. so At 1AU you'd have negigible gravity compared to earths gravity.

Re:

[Grishnakh]

So you're telling me that if you have a shell, 1 AU in diameter around the sun, and that is as thick as the earth, that there won't be any gravity on the inside?

That doesn't sound right to me at all.

Re:

[king-manic]

If it's as thick as the earth then yes it would have the gravity of the earth. But thats a massive amount of material. thousands of times more then in this solar system. Although the contruct would have earth like gravity, it would require so much material it would require thousands of star systems to create.

Re:

[Headw1nd]

actually, yes.

The trick is that the gravity of the mass under your feet is exactly counterbalanced by the gravity of the rest of the shell, the majority of which is above you. It's farther away, true, but the fact is there's so much more of it balances out the equation.

Now on the outside of the shell, gravity would work in a more expected fashion.

Re:

[Grishnakh]

Ok, this makes sense then.

If a civilization can create a 1AU-diameter ring around a star, finding enough material to make it that thick doesn't seem like a big challenge. Maybe this is a good reason for a ringworld instead of a Dyson sphere: it wouldn't require quite as much material.

Of course, a civilization that advanced could probably just make artificial gravity generators.

Re:

[king-manic]

Of course, a civilization that advanced could probably just make artificial gravity generators.

If it's possible. It may not. It's a huge object requiring a lot of fantastic technologies. But a shell less then earth thick and earth density of the earth would result in lower gravity. If it had a great deal more dendity it may need less overall mass. For instance if they had some way to use stable degenerate matter they wouldn't have to have it the thickness of earth and less mass as well.

Re:Ringworlds have a lot of problems

[CogDissident]

Assuming you have enough thrusters, and a good controll program, you could easilly compensate for up to 50-90% of the total thrusters being offline at a time, allowing you to do repairs at your leasure. And a dyson sphere DOESNT HAVE poles, none, its uniformally the same temperature the whole sphere over (minus whatever height differences, as peaks would be a bit colder due to less atmosphere or the bottoms of the oceans which could be a bit colder).

If you spin a dyson sphere, you dont have to simulate gravity, at all, and if the spinning mechanism failed, you would have a LOT of time to deal with it, as it would take a while for something spinning that fast to spin down to a point where people start falling off the surface. Assuming the loss of spin comes from too few functioning thrusters, then you would have an even slower spin-down because the tursters would compensate for the loss, at least a little.

Portals are a staple of most dyson spheres, but with something that big, the odds of having to leave very often are rather unlikely. Even if you did need to leave, reinforced circular portals would be good,it wouldnt compromise the strength of the sphere if it was curved at the same rate, and could be built as needed. Any single LARGE (drive a planet through it) portal could be difficult, but would not be impossible.

Re:

[ceoyoyo]

Poles aren't the cold part of a planet, they're the part where the spin axis comes out of the surface. So a spinning Dyson sphere does indeed have poles. And those poles have virtually zero gravity. In fact, there would only be a ring around the equator that would have full gravity (whatever you wished for that) and as you went north or south it would decrease. So the poles and temperate regions would be barren wastelands and you'd end up with essentially a ringworld. The only difference is that you'd

Re:

[Jerf]

If you spin a dyson sphere, you dont have to simulate gravity

But remember that in that case, the "gravity" is always perpendicular to the axis of the spin, so only people on the equator get gravity that is "down".

This results in only a single (relatively) thin strip at the equator being habitable, because all the air is down there. Then you wonder why you're building the rest of the sphere. Then you end up making just the ring, and making it stronger. And you're back to Ringworld. (Plus the Ring doesn't hav

Re:

[CogDissident]

I still think the sphere makes sense, because about 80% of it would still have gravity enough to support life, and the remaining 20% can be completely covered in solar panels to power the rest of the sphere, and whatever other energy needs you may have.

I say 80%, because even when your 9/10ths down the side of a spinning sphere, theres still enough centrifugal force to keep something there instead of falling inwards, the gravity might be 1/10th of earth normal, but thats liveable.

If you spun the equater

Re:

[dltaylor]

you missed a point: the "gravity" (centrifugal force) would not be perpendicular to the surface. midway between the "equator" and the "pole", it would be at a 45 degree angle to the floor.

you could, I suppose, build a "stepped sphere" ( like the hats in Devo's "Whip It" http://www.vh1.com/artists/az/devo/videos.jhtml/ [vh1.com] ), which is essentially a set of cylinders decreasing in radius from the equator to the poles, to solve the gravity problem. this results in the stellar light always arriving at the same ap

Re:

[CogDissident]

The stepped sphere idea is a good one, especially if you use a series of steps that are only a few miles wide. The reason you'd do that instead of immense steps is mostly because big steps would increase the amount of raw materials needed for construction significantly more than a series of small steps. Considering that a dyson sphere already requires several huge planets(jupiter and bigger) worth of materials to construct, an extra expendature of 50% more raw materials, which dont necessarilly need to be o

Re:

[krenshala]

But if you are 9/10ths of the way up/down from the equator to the pole, the direction of centrifugal force is NOT down. It is still perpendicular to the axis of rotation. Another way to look at why its not useful is a nice simple question: What degree of slope (or larger) makes a location unsuitable for use? 60 degrees? 30? I know hills with more than 15 or 20 degrees of slope have all kinds of warning signs for traffic to use caution, low gear, etc. That angle use usability would determine just how mu

Re:

[Sigma 7]

This results in only a single (relatively) thin strip at the equator being habitable, because all the air is down there. Then you wonder why you're building the rest of the sphere.

Energy collection. With ring worlds, you only get a small chunk of the sphere.

If a dyson sphere turns out to be an extra-wide ringworld, you can simply equip the uninhabitable terrain with solar panels to collect power. This clears up some space on the ringworld which can be used for other things. In addition, assuming that no energy is lost in transmission from the poles to the equator, you'd have much more power collected than simply using the ring itself.

Re:

[HiThere]

OTOH, if you chop off the ends to save the wasted space, you decrease the gravitational stability. A Dyson sphere is much less gravitationally unstable than a ringworld, because spherical shells of equally distributed mass have zero net internal gravitation. The instability of a Dyson sphere is caused because mass will NEVER be evenly distributed. And, of course, inertia. (A slow rotation would probably be advantageous for this reason...but not much, because you don't want to drag all of the air away fr

Re:

[sabre86]

It seems to me that a Dyson sphere would have a local gravitation field directed toward the surface. At small distances from the surface, this field should be approximately equal to that of the field produced by an infinite plate of finite thickness. Yeah, there's no net gravity field at the center, but unless the material the sphere is made from is massless, there will be a field near the surface. I should do the math, but I'm at work (at least, that's my excuse.)

--sabre86

Re:

[HiThere]

A single Dyson sphere wouldn't have enough gravity to hold an atmosphere, certainly not a breatheable one. So you live between two layers, and you build the layer closer to the sun transparent to allow for "natural lighting". Within the two layers there would, effectively, be no gravity. Beyond the outer layer..., yeah, there's gravity. Not much, but some. (Well, how much depends, of course, on how much mass the sphere contains, but you've got to remember that the center of gravity is at the sun's cent

Re:

[DerekLyons]

Note that as you don't spin a Dyson Sphere, net gravity is very low. About half that of the Sun's from the distance of the Earth. This makes ponds, lakes & seas possible (if not probable, and probably temporary), but quite dangerous. Rivers, however, are not going to occur.

If you have gravity enough to hold water in place - then you'll have water seeking it's own level, I.E. rivers.

Re:

[HiThere]

You don't spin it fast enough to hold water in place. The spin isn't for gravity, it's to ensure that the non-even distribution of mass doesn't cause stability problems. SLOW. This would probably result in 0.01g acceleration. Or less, you also don't want to strain the framework. You build it of something as close to saran-wrap as you dare! Materials for this much construction are EXPENSIVE!! in whatever currency you are using.

Think of it as a super-high-tech Space Station and you'll be close to correc

Re:

[julesh]

Dyson spheres have similar issues to ringworlds, i.e., if you're using rotation to provide psuedogravity you have stability issues (on a dyson sphere this manifests itself as the habitable area wandering over the surface of the sphere over time). If you're relying on mass, you're going to need a lot of it, much more mass than would be required for a similarly sized ringworld.

I think the answer is to forget the idea of having a star in the middle, which enables you to build substantially smaller. The ringw

What about the edges?

[Floritard]

I'm far too lazy to read the article, fanboys have all but ruined Halo for me, but does it mention anything about what happens on the edges of the Halo world? Would be really cool if they had a level in Halo near the edge. It's funny how they just kinda ignore that the game takes place on a world that actually has the pre-Columbus world-with-edges setup going on. What happens to the atmosphere (atmocylinder?) at the edge? If you're flying in an aircraft can you fly over the edge given enough momentum? How are the seas held back, etc?

Walls

[argent]

There are walls all along the rim, high enough to keep the atmosphere in.

Re:

[Floritard]

Actually I have to call bullshit on that one. The first game presents the ringworld quite clearly on the title screen and there is no evidence of there being any high walls. If you look you can actually see the oceans running all the way up to the edges of the ring. So the atmocylinder (is no one going to challenge that crappy portemanteau?) cannot be kept at bay with walls. Is this something stated in the Halo novels or what? Walls would have been cooler anyway. Massive fucking walls on the horizon.

Re:

[argent]

The first game presents the ringworld quite clearly on the title screen and there is no evidence of there being any high walls.

http://games.monstersatplay.com/assets/screenshots /halo/halo-016.jpg [monstersatplay.com]
http://games.monstersatplay.com/assets/screenshots /halo/halo-017.jpg [monstersatplay.com]
http://games.monstersatplay.com/assets/screenshots /halo/halo-024.jpg [monstersatplay.com]
http://games.monstersatplay.com/assets/screenshots /halo/halo-027.jpg [monstersatplay.com]

It sure looks like there are walls in these pictures. Don't forget that Halo is 53 kilometers across, so fair

Re:

[slycrel]

The halo books go into much more detail on this kind of thing, assuming you're interested enough you'd get your best answers from them.

Re:

[necro2607]

I seem to recall reading that there are 1-2km high walls on either side to "hold the atmosphere in", which may or may not be a very realistic concept...

Re:

[MikeyNg]

You use "Spill Mountains" on the edges. Basically, you make mountains 1,000 miles high on the rim to prevent spillage. (If you can build a ringworld, you can build mountains 1,000 miles high.) That's reasonably above a large portion of the atmosphere such that very little should spill out. By the way, you also use the mountains on the edge to put back soil that you naturally lose through erosion. :)

Re:

[Jake Dodgie]

They were called spill mountains, because sludge from the sea bottoms was pumped up through the edges and spilled down the internal sides of the atmosphere walls. A massive effort of recycling dirt.

Re:

[Devar]

I seem to recall that the traditional nomenclature of ringworlds is that the edges feature really big walls. Think of a cross-section of a ringworld like this:

[ * ]

With the brackets being the ring structure and the asterix being the central star. Because the ringworld spins, there's a centrifugal (or is it centripetal? IANAP) force keeping all the air/ocean/etc in. Like spinning a bucket full of water around.

not Niven... Banks

[tabby]

I'm tired of people making comparisions of the Halo 'installations' of Bungie's to the Ringworld of Niven.

Apart from basic shape they have nothing in common. The Halo's most apparant ancestor would be the orbitals ( http://en.wikipedia.org/wiki/Orbital_(The_Culture) [wikipedia.org] ) from Ian M Banks' "Culture " novels. It's rather apparant that Bungie drew much more inspiration from Banks' work than from Niven. http://www.marathon.org/story/halo_culture.html [marathon.org]

Another Smart Pop Book

[PhoenixOne]

Not to disrespect somebody's work, but the Smart Pop books I've read had a lot of silly high-school level logic and analysis.

The read much like transcripts of drunk chats with undergrad students. Not that this is always a bad thing. :)

Ah yes, Halo

[Trogre]

"Your destruction is the will of the Gods, and we are their instrument!"

I still remember the red alien speaking those words in the teaser trailer. Of course that was before the game got bastardized into an X-Box (*spits*) title.

Additionally I hope there's no one here who thinks Bungie invented the ringworld.

maths

[RagnarokGod]

since radius=5000 ergo diameter=10000, then would not circumference be 31415.926536? oops, forgot 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0



09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

Re:

[T-Bone-T]

There's a reason this was posted by an AC. Please note the "Coward" portion of the name and start modding this shit down.

Re:

[LionMage]

That's why these rings are spun on their axis (which passes through the center of gravity) to simulate gravity via centripetal acceleration. Some call that "centrifugal force," but my high school physics teacher insisted (as do many textbooks) that this is an erroneous term because the force is "fictitious" [nasa.gov]. (Yeah, being the smart-ass with the top grade in the class, I asked her how she explained the operation of a centrifuge -- especially one large enough to hold people, like certain carnival rides and t