Okay, go on with whatever you were doing.
The Disc
What's bigger than a Dyson sphere? Dan Alderson, designer of the Alderson Double Dyson Sphere, now brings you the Alderson Disc. The shape is that of a phonograph record, with a sun situated in the little hole. The radius is about that of the orbit of Mars or Jupiter. Thickness: a few thousand miles.
Gravity is uniformly vertical to the surface (freshman physics again) except for edge effects.. Engineers do have to worry about edge effects; so we'll build a thousand-mile wall around the inner well to keep the atmosphere from drifting into the sun. The outer edge will take care of itself.
This thing is massive. It weighs far more than the sun. We ignore problems of structural strength. Please note that we can inhabit both sides of the structure.
The sun will always be on the horizon, unless we bob it, which we do. (This time it is the sun that does the bobbing.) Now it is always dawn, or dusk, or night.
The Disc would be a wonderful place to stage a Gothic or a swords-and-sorcery novel. The atmosphere is right, and there are real monsters. Consider: we can occupy only a part of the Disc the right distance from the sun. We might as well share the Disc and the cost of its construction with aliens from hotter or colder climes. Mercurians and Venusians nearer the sun, Martians out toward the rim, aliens from other stars living wherever it suits them best. Over the tens of thousands of years, mutations and adaptations would migrate across the sparsely settled borders. If civilization should fall, things could get eerie and interesting.
Cosmic Macaroni
Pat Gunkel has designed a structure analogous to the Ringworld. Imagine a hollow strand of macaroni six hundred million miles long and not particularly thick—say a mile in diameter. Join it in a loop around the sun.
Pat calls it a topopolis. He points out that we could rotate the thing as in the illustration—getting gravity through centrifugal force—because of the lack of torsion effects. At six hundred million miles long and a mile wide, the curvature of the tube is negligible. We can set up a biosphere on the inner surface, with a sunlight tube down the axis and photoelectric power sources on the outside. So far, we've got something bigger than a world but smaller than a Ringworld.
But we don't have to be satisfied with one loop! We can go round and round the sun, as often as we like, as long as the strands don't touch. Pat visualizes endless loops of rotating tube, shaped like a hell of a lot of spaghetti patted roughly into a hollow sphere with a star at the center (and now we call it an aegagropilous topopolis.) As the madhouse civilization that built it continued to expand, the coil would reach to other stars. With the interstellar links using power supplied by the inner coils, the tube city would expand through the galaxy. Eventually our aegagropilous galactotopopolis would look like all the stars in the heavens had been embedded in hair.
The Megasphere
Mathematically at least, it is possible to build a really big Dyson sphere, with the. heart of a galaxy at its center. There probably aren't enough planets to supply us with material. We would have to disassemble some of the star of the galactic arms. But we'll be able to do it by the time we need to.
We put the biosphere- on the outside this time. Surface. gravity is minute, but the atmospheric gradient is infinitesimal. Once again, we assume that it is possible for human beings to adapt to free fall. We live in free fall, above a surface area of tens of millions of light years, within an atmosphere that doesn't thin out for scores of light years.
Temperature control is easy: we vary the heat conductivity of the sphere to pick up and hold enough of the energy from the stars within. Though the radiating surface is great, the volume to hold heat is much greater. Immustrial power would come from photoreceptors inside the shell.
Within this limitless universe of air we can build exceptionally large structures, Ringworld-sized and larger. We could even spin them for gravity. They would remain aloft for many times the lifespan of any known civilization before the gravity of the Core stars pulled them down to contact the surface.
The Megasphere would be a pleasantly poetic place to live. From a flat Earth hanging in space, one could actually reach a nearby moon via a chariot drawn by swans, and stand a good chance of finding selenites there. There would be none of this nonsense about carrying bottles of air along.
One final step to join two opposing life styles, the Macrolife tourist types and the sedentary types who prefer to restructure their home worlds.
The Ringworld rotates at 770 miles/second. Given appropriate conducting surfaces, this rotation could set up enormous magnetic effects. These could be used to control the burning of the sun, to cause it to fire off a jet of gas along the Ringworld axis of rotation. The sun becomes its own rocket. The Ringworld follows, tethered by gravity.
By the time we run Out of sun, the Ring is moving through space at Bussard ramjet velocities. We continue to use the magnetic effect to pinch the interstellar gas into a fusion flame, which now becomes our sun and our motive power.
The Ringworld makes a problematical, vehicle. What's it for? You can't land the damn thing anywhere. A traveling Ringworld. is not useful as a tourist vehicle, anything you want to see, you can put on the Ringworld itself... unless it's a lovely multiple star system like Beta Lyrae but you just can't get that close on a flying Ringworld.
A Ringworld in flight would be a bird of ill omen. It could only be fleeing some galaxy-wide disaster.
Now, galaxies do explode. We have pictures of it happening. The probable explanation is a chain reaction of novae in the galactic core. Perhaps we should be maintaining a space watch for fleeing Ringworlds ... except that we couldn't do anything about it.
We live on a world: small, immobile, vulnerable, and unprotected. But it will not be so forever.
$16,949.00
When the phone rings late at night, there is a limit to who it can be. I had three guesses as I picked it up: a wrong number (all wrong numbers are the same person), or Lois, or—I didn't bother to think his name. It isn't his anyway.
"Hello?"
"Hello," he said. "You know who this is?"
"Kelsey." It's the name he tells me. "What is it, Kelsey? You're not due for another four months."
"I need an advance. Are you sitting down?"
‘Tm in bed, you son of a bitch." Reading a book, but I didn't tell him that. Better he should be off balance.
"Sorry. I just wanted you braced. I need sixteen thousand—"
"Bug off!" I slammed the phone down.
There was no point in picking up the book. He'd call again. Sometimes he waits a few minutes to make me nervous. This time the phone started ringing almost immediately, and
I snatched it up in the same instant and held it to my ear without saying anything. It's a kind of bluffing game, a game I always lose.
"Kelsey again, and I'm not kidding. I need sixteen thousand, nine hundred and forty dollars. I need it by the end of the week."
"You know perfectly well I can't do that! I can't make that much money disappear without somebody noticing: Lois, the bank, the Bureau of Internal Revenue. Dammit, Kelsey, we've worked this out before."