[Bloody Sam Roberts]

A sufficiently active dyson sphere might glow in infrared but we'd think of it as a likely failed star!

"I myself have dreamed up a structure intermediate between Dyson spheres and planets. Build a ring 93 million miles in radius - one Earth orbit - around the sun. If we have the mass of Jupiter to work with, and if we make it a thousand miles wide, we get a thickness of about a thousand feet for the base.

And it has advantages. The Ringworld will be much sturdier than a Dyson sphere. We can spin it on its axis for gravity. A rotation speed of 770 m/s will give us a gravity of one Earth normal. We wouldn't even need to roof it over. Place walls one thousand miles high at each edge, facing the sun. Very little air will leak over the edges.

Lord knows the thing is roomy enough. With three million times the surface area of the Earth, it will be some time before anyone complains of the crowding."

- - Larry Niven, "Ringworld"

[no-to-illegals]

Your thought is not as far fetched as one would tend to believe. Given the recent NASA thoughts of capturing an asteroid and placing the asteroid in orbit around the Moon, the possibilities are endless if one becomes serious. Being from old school was taught nothing is impossible. One of my greater flaws am currently told.

[muawiyah]

it may be easier to build a Dyson sphere than a Ringworld. Or, let's say we just keep building ringworlds around a star as we need more and more living space ~ we cant them in their orbits.

Eventually there'd be so many rings we'd capture 100% of all the central star's energy. Still wouldn't be a sphere but it'd do everything we can do with a sphere, plus the gravity is the same everywhere we go.

The living space would be incredible.

I read all the same books myself.

Now, something you didn't read in books ~ the intergalactic wanderers travel about in far smaller vessels ~ but they mine planets for the purpose of acquiring minerals useful for sustaining life ~ you find a lot of that in the surface layers of planets with oceans.

Let's say they came into our solar system and began mining Venus ~ using that planet's then moon Mercury as a device for tossing loads of surface phosphates and carbonates to the outer limits of our solar system.

They finished up there when Mercury broke loose from Venus' control and became an independent planet itself.

Then they turned to Earth and began the same mining. Again, they used this local moon to toss loads farther out for pickup by the great space cruising ships.

They wrapped up operations here before they'd gobbled up all the continental land masses. On Venus they got all that stuff. That planet has no carbonates ~ just igneous bedrock.

Needless to say I"ve kept my eyes open for evidence, since mining on that scale ought to have left something for us to see.

There is evidence. The deepest hole in the solar system is smack dead center at the Moon's South pole. That's where the structure holding the giant boom arm that tossed loads was anchored, and around which it rotated.

Mercury has some areas of spreading basalt that suggest it, too, had once had a large hole dug out at one of the poles, probably for another boom arm.

There might be a 'construction shack' somewhere ~ and there's other evidence including the distribution of the easy to pump hydrocarbons on the planet. They've all been found in a zone that was THE EQUATOR at the time they formed. Are these the remains of the planet girdling space elevator system used to tote the loads up to the Moon? And really now, what happened to 60% of our surface ~ why are there only continents rather than a sturdy shell?

All possibilities for speculation.

[deks]

I had not heard of Ringworld when I saw your post. Coincidentally, the author Larry Niven is being interviewed right now on the Coast To Coast radio program (5:15 a.m. EDT).