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Honestly, bulding a dyson sphere???

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Post Wed Jul 09, 2003 4:19 am

Therein lies the problem. You have an extremely massive sphere (massive enough to generate considerable gravity on its outer surface), which while has no net gravitation effect on anything on the inside, everything on the outside, (Including The Material The Sphere Is Made Of!) will still be attracted to it as if all the mass is concentrated at the center of the hollow sphere.

Unless that planet-orbit-sized dyson sphere is built VERY strong to support the gazillions of tonnes of mass it must have, it will STILL collapse towards its center. We are talking about materials with a few gazillion times the tensile strength of today's structural steel.

Or let's for a moment assume that it's not structural strength keeping the sphere from imploding but some sort of active system that requires energy input (say with some sort of heated gas in the interior to provide outward pressure to keep it from collapsing). The energy usage would be so massive so as to defeat the purpose of building the dyson sphere in the first place (collecting all the energy from the sun it is enclosing).

I remain unconvinced.

Post Wed Jul 09, 2003 12:21 pm

the sun throws out enought matter and energy(aka solar wind) to allow anything with a sail to reach nearly half the speed of light, a small sail would allow a geostationary orbit around the sun due to a fine balance between the suns gravity and the mass it expells. the dyson sphere (all around the sun) would catch ALL of the matter which will create a huge force pushing outwards. this would help compensate for some of the gravity, thus leaving the structure intact. this would also build up a certain presure further aiding the structural intergity.
also a massive factor to have in mind is exactly how large is the sphere? i read over at another tread that it would encompase the entire solar system. this would defeat the purpouse of the sphere as the planets would absorb quite a bit of energy, the best place would be just below the smallest orbit, or smaller still depending on the actual material its made of... such a small sphere wouldnt need much structural support due to the solar wind metioned above

Post Wed Jul 09, 2003 10:53 pm

Well, that solar sail thing is still theoretical. Keep in mind also that the density of the light and solar wind particle flux decreases at a cubic function of distance from the star. If you take Sol for example, its light has the intensity of a 20-watt bulb by the time you reach Pluto. Accelerating even a small a solar sail to 1/2c in the distance from Earth to Pluto? No way.

Also, solar sails are supposed to be made of the lightest, flimsiest, least dense material. You can't do that with a dyson sphere if you want to build a world on its surface.

Post Thu Jul 10, 2003 1:53 pm

due notice that the game happens a couple centuries (not sure how long a time, just a long time) from now... by then we have allot of really cool space stuff which can do alot of things that we cannot even begin to imagine. the teoretical basis exists to build a dyson sphere. with our present technology and resources we cant build it, but by the time we travel to far away star systems like we now travel to a cornershop, we might be able to...

Post Thu Jul 10, 2003 2:49 pm

To quote a famous saying, 'Who cares?'

Cardamine rules!!

Post Fri Jul 11, 2003 12:53 am

to Aceaz: We do.

to Dexter: Well, actually all this time I've been expounding on why the theoretical basis for a dyson sphere is not sound at all. As far as I'm concerned, there is really no reason to build a dyson sphere. If a spacefaring race is at the technological level where building a dyson sphere is possible, there really isn't any reason to-- Why go to the effort and expense of building a whole sphere around a star system when they can just travel to other star systems and settle other habitable planets or terraform inhospitable worlds? That sounds much more economical to me.

Post Fri Jul 11, 2003 6:27 am

"there is really no reason to build a dyson sphere. If a spacefaring race is at the technological level where building a dyson sphere is possible, there really isn't any reason to-- Why go to the effort and expense of building a whole sphere around a star system when they can just travel to other star systems and settle other habitable planets or terraform inhospitable worlds?"


i was just about to say that... lol

- saw -

my other signature is a ferrari

Post Fri Jul 11, 2003 12:37 pm

Maybe their reason for building a dyson sphere was to piss us off, you know, make it a big arse task to finish the game, just a possibility but i think it makes more sense, ay...lol

Corsair - "Im gonna use whats left of you to grease my ship..."

Post Fri Jul 11, 2003 1:32 pm

I completely agree with Chandeskra thingly limit (is that right?). If you can make one, you dont need to . Though in the future they might be made just for fun!! Think about it....a thousand years ago you couldnt fly, now people are flying homemade planes across the atlantic. Just imagine with supertechnology where you COULD build one but you didnt need to. People would inevitably try even if you didnt need to. I think it would be done one day just because its such an outrageous idea and people or aliens or whatever they are would do it for a laugh.....I might trya nd make one around a fire and see what happens....

Post Fri Jul 11, 2003 2:28 pm

100 years ago we couldnt fly 2 feet of the ground
in less that a century we flew to the moon

Post Sat Jul 12, 2003 2:36 am

Just a comment or two...

The mass of the sphere will scale with r^2, as will g, so regardless of the radius, the force exerted on the sphere by itself will remain constant. Radiation pressure will be irrelevant... you are not producing a closed system, and the radiation pressure in either direction will be equal.

It would collapse, with any kind of concievable technology, but having said that, the major construction problem would be construction, before it supoprts its own weight. If you had all of the mass near its final position, then you'd have to be pushing outwards pretty damn hard to keep it all in place.

Of course, you could produce an orbiting 'sphere' made up of lots of little rings, which would obviously be in freefall. Then you could stand inside, as in the multitude of sci-fi ring concepts. The only difference being you have a ****load of them.

Post Sat Jul 12, 2003 11:10 am

To , pretty much everyone:
the point of a dyson sphere is to collect ALL the energy the star produces, it has been proposed that this energy is needed to keep the hypergate system running.there is no power source like it (exept if you do a similar thing to a black hole). there is your reason. since it is already there, it might then(only then) be used to put people on it
To athlondies:
the sphere IS a closed system but it should only encompase the star itself, anything more would be a waste of resources.
the mass would go up with r^3 not r^2 since it is a sphere not a ring. g is propotional to mass directly (going up as the mass increases). but changes (reduces) with the square of the distance from the center of the mass.
it would be possible to build loads of geostationary satalites around the star (which we can do now so any nomad like civilisation will do it much better) and slowly start to group them into o full shell.
the 'radiation pressure' would obviously be pushing in each direction equally but you are thinking in the wrong type of coordinates (some high end math concepts coming up), look at it with polar coords, you will see that the force will be equal for any value of theta but in the oposite direction of the force exerted by gravity, thus canceling it out to some extent. also there would be the solar wind, which is simply mass pushing outwards in all directions further helping the structure. another factor that would help is the material it is all made of. some space-age alloy that is very light but very strong would keep the whole thing in tact
did i miss anything?

Post Sat Jul 12, 2003 11:10 pm

Its a hollow sphere, not a solid one, so the mass scales with r^2. Solar wind would push outwards, very mildly, but would result in greater radiation pressure on the outward side as it heats up the sphere. Geostationary satellites can only be constructed around the equator, so you could only produce a ring.

Maybe they just had a whim- we fancy building a dyson shpere, cause we bet no-one else has. Hah. Bitches. We 4r3 w1nn4rs. etc.
Im sure there have to be better ways of powering a big system than building a dyson sphere- for one, just build lots of non-contiguous satellites/rings that will be around as efficient (well... not quite) and wont have to support themselves.

Post Sun Jul 13, 2003 5:13 am

Comrades, we are forgetting that the only reason we do not fall into the sun is because we are going fast enough sideways to keep missing it. If such a ring was constructed, it would have to spin fast enough proportional to its mass to maintain a constant distance from the sun. Too fast and it would break apart and fly outwards, too slow and it would crush itself and fall into said sun.

True, the net force inside a sphere is zero, that is, zero net force from the SPHERE ITSELF. With an absence of force to keep anything on its inner surface, everything would once again fall into the sun, the only sorce of gravity.

So, the only way to counter this would be for the sphere to spin, but spin in what direction? Only a small band (or two small bands) along the latitudinal axis of the spin would maintain sufficient speed to compensate for said sun's gravity, and all of the rest would be going too fast or too slow (and the poles would not be moving at all) and would consquently fall to pieces.

In effect, it is not possible to build a sphere around a star. Good thing this is just a game, eh comrades?

High Treason! Now there is a two ended club. It all depends on which end you have hold of.

Post Sun Jul 13, 2003 7:06 am

A spinning hollow sphere will collapse for sure. Even solid spheres like earth deform (flatten at the poles and bulge out at the equator) due to its spin.

As far as the gravitational forces and mass of a theoretical dyson sphere goes... Its mass will scale with two things: The first would be how thick the dyson sphere is: (outer radius)^3 - (inner radius)^3. THe second would be the density of the material it is constructed from. The gravitational force acting on itself will NOT depend only on the radius of the sphere, but the density also.

I've said it before and I will say it again: The structural strength for something like this would be IMMENSE. There is one general rule of thumb in architecture: the strength of the structural material generally needs to increase in proportion to the size of the structure. Sure, one can make superstrong lightweight space-age alloys for little things like space ships and space stations, but for a structure as HUGE as a dyson sphere the material will have to be correspondingly stronger-- A few gazillion times stronger.

That hypergate thing is kind of puzzling as well. If everyone in the FL universe can get around fine with jumpgates and jumpholes, why does anyone need a hypergate that needs a dyson sphere to power it? Why even go to the trouble of building a hypergate that will be used like maybe once every few thousand years and go to the trouble, expense and effort of building a whole dyson sphere to power it? One would think an advanced civilization with superior intellect would be a bit less impetuous and not prone to profligate, wasteful projects that serve little purpose..

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