Lt. Commander
Join Date: Dec 2007
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# 11
05-31-2012, 09:54 AM
as I said a Moving one Eats the sphere (incidentally Stars do swallow planets eventually as well in some cases)
Lt. Commander
Join Date: Dec 2007
Posts: 120
# 12
05-31-2012, 10:39 AM
Lt. Commander
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# 13
05-31-2012, 10:59 AM
That might not have been the first Dyson sphere. There is also the race from the Corbomite Maneruver, who had a spherical ship large enough to potentially be a dyson.
Lt. Commander
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# 14
05-31-2012, 11:19 AM
Quote:
Originally Posted by bluegeek View Post
The "shell" encapsulating the star has to have a diameter roughly that of the orbit of an M class planet to be inhabitable. The star's gravitational pull would act on the entire sphere at that distance and theoretically carry it along for the ride as it moves in its' orbit of the galaxy. The star would not "eat" the sphere any more than it would "eat" a planet in orbit around it. Effectively, the entire sphere would be in orbit around the star and would need to have some kind of spin around the star. Dyson's Spheres shouldn't be able to affect the star they encapsulate and would not be able to navigate independently. They're basically astronomically large space stations/habitats.
Pretty much. We sort of lack the engineering to check to see if it works, but I'd say Freeman Dyson did his homework and knows of what he speaks.

Quote:
Originally Posted by bluegeek View Post
No argument about totally impractical. It's just a theory and probably not possible to construct one. But it's a cool idea even if the engineering of a Dyson's Sphere (or a Ringworld) is beyond our technology. It was neat to see one in TNG. TNG even got the main drawback of a Dyson's Sphere right: any solar instability would make it uninhabitable if not destroy it.
Not just being subjected to the whims of solar instability, a Dyson sphere's engineering alone is a nightmare! Consider that at the equator of a Dyson sphere that is one AU in diameter, to get approximately one gravity of "downward"/"outward" acceleration the sphere would need to be rotating at (unless my calculations are wrong) about 1220 kilometers per second. There are serious engineering feats required to accelerate something to that speed, let alone deal with the centrifugal stresses!* Even Larry Niven had to resort to magitech "scrith" to make the base materiel of his Ringworld; I don't imagine the base layers of a Culture plate (from Ian M. Banks's novels) is any less magitech.

Now add in the fact that simple entropy, solar flares/CMEs, and even subtle gravitational changes will cause the orbit to "wobble;" there's no such thing as a perfectly circular orbit or a perfectly stable orbit. Now you have a sphere spinning at over four million km/h, and it's wobbling like a top spun by a three-year-old Q. This is why MIT students marched through WorldCon once, chanting "The Ringworld is unstable! The Ringworld is unstable!"


* - On the other hand, at that point interstellar travel becomes almost-but-not-quote trivial. Simply stick your ship on the outside of the sphere, wait for the right moment, then let it go. It will proceed at 0.004c on the same direction. It may take a millenium for it to get to the next star system, but that's better than many tens of thousands of years, you can still accelerate the sucker with an onboard reaction engine or a laser sail, and if you're building a Dyson sphere, you're playing the long game anyway. On the gripping hand, if you're building a Dyson sphere, cheap and fast interstellar travel is probably the least of the magitech in your bag.
Lt. Commander
Join Date: Dec 2007
Posts: 120
# 15
05-31-2012, 11:26 AM
Quote:
Originally Posted by bluegeek View Post
I think perhaps you're missing the idea of what a Dyson's Sphere is.

The "shell" encapsulating the star has to have a diameter roughly that of the orbit of an M class planet to be inhabitable. The star's gravitational pull would act on the entire sphere at that distance and theoretically carry it along for the ride as it moves in its' orbit of the galaxy. The star would not "eat" the sphere any more than it would "eat" a planet in orbit around it. Effectively, the entire sphere would be in orbit around the star and would need to have some kind of spin around the star. Dyson's Spheres shouldn't be able to affect the star they encapsulate and would not be able to navigate independently. They're basically astronomically large space stations/habitats.

No argument about totally impractical. It's just a theory and probably not possible to construct one. But it's a cool idea even if the engineering of a Dyson's Sphere (or a Ringworld) is beyond our technology. It was neat to see one in TNG. TNG even got the main drawback of a Dyson's Sphere right: any solar instability would make it uninhabitable if not destroy it.
Actually because the stars gravity is acting equally on every part of the sphere,so the net effect is it cancels itself out. The only way to move the whole lot would be to have the sphere move and take the sun with it.

That said it wouldn't be hard for whoever built the thing to do. A fairly decent scientist and one of the book authours sat down and wrote a book about a trip back there, in it is laid out what woulkd be required to build it. Every dust mkote, asteroids, comet, planet, and star for 500 light years in every direction. The result totals around 10,000 star systems simply hoovered up and carted off to build it. Let me repeat that, 10,000 stars, and everything in their solar systems, and everything in the gulfs between them.

Anyone who can do that can bassiclly flip their finger at the laws of physics as we know them, and rub out any race upto and including our new gateway using "freinds" and not even notice they done it.

EDIT: The originol dyson sphere wasn't a sphere at all, it was millions of solar power sats arranged in orbits that formed a spehere around the tar, allowing all it's radiant energy to be captured for power beaming. It was a means to capture all the stars radiant energy, living area's or a single solid structure where never part of the equation.

The TNG sphere gets a free pass on gravity BTW. Besides the obvious option of artificial gravity generators, the nuetronium skin if of the right thickness and distance from the inner surface would create asurface pull fo exactly 1G. No need to spin it then.
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# 16
05-31-2012, 02:38 PM
For people who aren't really getting the scale of such a thing, think of it this way. Your ship is parked next to ESD. Past that, where the Earth would normally be, is the outer surface of a Dyson sphere. It looks like a wall that stretches as far as you can see, filling nearly 180 of your field of view.

No. You're not getting one.
Lt. Commander
Join Date: Dec 2007
Posts: 120
# 17
05-31-2012, 03:58 PM
Maybe they meant Borg? :p
Lt. Commander
Join Date: Dec 2007
Posts: 120
# 18
05-31-2012, 06:26 PM
Quote:
Originally Posted by sollvax
only if you can move a critical mass point (which science says you can't)
Actually dyson spheres are totally impractical and one of the daftest ideas in scifi

you see Stars Move
and as a star has massive gravity eventually it would EAT the sphere


Ummm... No, science most certainly does not say you can't move a critical mass point... Because stars are in constant motion, even our own at this very instant, and the motion of innumerable stars in the universe are constantly perturbed by other stars, and gravitational effects...

Even Newtonian models could have noted that... Much less a relativistic model...

As for the star at the center of the dyson sphere consuming the sphere itself, no, it wouldn't consume the sphere if it were in a sufficiently large enough distance from the star itself that it would have an otherwise stable orbit were it something akin to a planet. That being said finding such a balance in all three axes, X/Y/Z, with such a profoundly large mass as a dyson sphere would be (very easily arguably many times the masses of the star it encircles) then the star itself would then in effect be gravitationally locked to the sphere rather than the other way around.

One could not easily move it however, as the gravitational "wake" if you will, would not provide for much constrictive force should the sphere attempt any significant acceleration along another path than the inertia of the sphere and star within it were already accustomed to following.



Anyway, for as profoundly complex and difficult as a dyson sphere would be to make, any beings capable of making one, would find that overcoming the issues of motility in it would seem a paltry afterthought.
Lt. Commander
Join Date: Dec 2007
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# 19
05-31-2012, 07:09 PM
Quote:
Originally Posted by APhantasm72 View Post
I think this is akin to an April Fools joke. A Dyson Sphere is not a ship, and is stationary due to the star at the center of it. And on top of that is so big, think the diameter of the Earth's Orbit around the sun. There is just no way to make such a huge thing an actual ship.
Have you read the Troy Rising series by John Ringo? Really interesting series. Starts with Live free or Die then goes to Citadel and the final one so far is The Hot Gate. My point though is that there actually IS a way to get something that big (or nearly) to move. It's called an Orion Drive. Read the series and you'll understand.
Lt. Commander
Join Date: Dec 2007
Posts: 120
# 20
05-31-2012, 11:44 PM
A Dyson Sphere or even a Borg Dyson Sphere would make for an interesting STF.
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