A New Type of Dyson Sphere May Be Nearly Impossible to Detec

[Galadrion]

Hm. Ways of dealing with getting light/energy/et cetera on the outside of a Dyson Sphere...

Well, since we're already discussing building projects which are, in one way or another, beyond Imperial tech, why not line the inside surface of the sphere with photovoltaic panels, and then transmit the generated power to artificial lighting/heating facilities on the outside? Granted, they'd probably need to be more efficient and durable than anything we can make in that line, but we're already talking about a construction beyond what we can manage. Seems to me that this would be less of a stretch than building the thing it the first place would be.

Overall, I'd say that a project like this would be just within the limits of what the late Imperium could manage, technically, but that it would probably be economically infeasible. (To translate to gamerspeak: at TL 15, it could be done, but it would probably cost on the close order of the aggregate GWP of somewhere between a subsector and a sector for a century or so.) Give it two or three additional TLs, and you'd probably be able to bring the cost down to something a single system could support, in a building project taking something closer to a decade. The Ancients? Pfft. Grandfather'd probably drop off a few robotic work crews in an empty system and expect to come back in a few years to find the whole shebang up, running, and ready for him to issue new policy directives.

At a rough benchmark, I'd place a practical, functioning Dyson Sphere at around TL 18, but it would be the Hoover Dam or Moon Mission of it's time and place. A Ringworld would be similar. Rosettes... they'd probably be similar to initially build, but would need fairly close monitoring and adjustment at that level; setting up a stable rosette over geological or stellar timescales would probably add another TL to the requirements, since any other significant mass in the system is going to tend to destabilize things.

 

[Tom Kalbfus]

Hm. Ways of dealing with getting light/energy/et cetera on the outside of a Dyson Sphere...

Well, since we're already discussing building projects which are, in one way or another, beyond Imperial tech, why not line the inside surface of the sphere with photovoltaic panels, and then transmit the generated power to artificial lighting/heating facilities on the outside? Granted, they'd probably need to be more efficient and durable than anything we can make in that line, but we're already talking about a construction beyond what we can manage. Seems to me that this would be less of a stretch than building the thing it the first place would be.

Overall, I'd say that a project like this would be just within the limits of what the late Imperium could manage, technically, but that it would probably be economically infeasible. (To translate to gamerspeak: at TL 15, it could be done, but it would probably cost on the close order of the aggregate GWP of somewhere between a subsector and a sector for a century or so.) Give it two or three additional TLs, and you'd probably be able to bring the cost down to something a single system could support, in a building project taking something closer to a decade. The Ancients? Pfft. Grandfather'd probably drop off a few robotic work crews in an empty system and expect to come back in a few years to find the whole shebang up, running, and ready for him to issue new policy directives.

At a rough benchmark, I'd place a practical, functioning Dyson Sphere at around TL 18, but it would be the Hoover Dam or Moon Mission of it's time and place. A Ringworld would be similar. Rosettes... they'd probably be similar to initially build, but would need fairly close monitoring and adjustment at that level; setting up a stable rosette over geological or stellar timescales would probably add another TL to the requirements, since any other significant mass in the system is going to tend to destabilize things.

Here is a larger version of this image.
http://imageshack.com/a/img822/6954/9o4s9.jpg
This is the scaffolding under the surface of the Dyson Sphere, as you can see it consists of a number of overlapping rings, inside are the centrifuges that hold the Dyson Sphere up against the White Dwarf's gravity. In order for this to work centrifugal force needs to balance out the attactive force of gravity on the Dyson Shell above this superstructure. As for say Sirius a pulling the sphere off center, I have to remind you that the center of gravity of the Dyson sphere is the same as the center of gravity of the star in the center, so to the degree that Sirius a pulls on the Dyson Sphere it also pulls on Sirius b in the center. As for candidates as to who built this, lets say it was the Ancients during the time of the "Long Night" No one was paying any attention to the Sirius System at the time.

 

[Reynard]

I think you are misinterpreting what a centrifuge is. I'd say there would be tremendous inward facing thrust engines to make corrections to any drift.

 

[Tom Kalbfus]

I think you are misinterpreting what a centrifuge is. I'd say there would be tremendous inward facing thrust engines to make corrections to any drift.

Actually all forces from the star on the Dyson Sphere would cancel out if the mass of the sphere is evenly distributed. If the Sphere goes off center, then the forces on the close surface to the star would equal the forces on the far side, unlike a ringworld. Even if one side is half the distance from the star than the far side, this would be true and more of the sphere would be far away than close, so there is more mass and less gravity farther away and less mass and more gravity up close. So if the sphere is off center, the near surface won't accelerate towards the star. there is one caveat, if the sphere is off center, it would be affected differently by the second star Sirius a. So long as the Sphere is kept centered on Sirius b, then the difference of a's pull on b and on the Sphere won't be much.

A cooler white dwarf of the same mass could have a surface gravity of 1-g, and the referee doesn't have to explain how it was suddenly built. The great thing about this is these small Dysons are hard to detect, there could be one a couple light years from Sol, and unless we knew precisely where to look, we wouldn't know it was there, perhaps that is what I ought to do, the sphere in this case would be under 8 million kilometers in diameter instead of 16 million, gravity would be 4/5ths of Earth's gravity instead of 1/5th. If it was close enough to the Solar System, we wouldn't need an FTL drive, there would be hundreds of thousands of Earths worth of surface area on that Dyson, of course if it self-illuminates it should be visible through our telescopes.

 

[Reynard]

"would equal the forces on the far side, unlike a ringworld"

The iconic ringworld had Bassard engines lining the ring wall to make corrections.

 

[Tom Kalbfus]

"would equal the forces on the far side, unlike a ringworld"

The iconic ringworld had Bussard engines lining the ring wall to make corrections.

No reason why you could not do something similar here, this Dyson Sphere has holes in it after all. The radiation has to be let out and some of it reflected back onto the sphere. Now that I think about it, the Sphere's radius doesn't have to be in the habitable zone either, so long as you can reflect the light away from the underside of the habitable surfaces and redirect it through the holes, and then reflect only some of it back onto the sphere for daylight.