FYS: Mass Defects (world building)

[jeriendhal]

Okay, I'm writing a big arsed piece of exposition for the beginning of Rise of the Ring, detailing what the Groupmind was up to for the last millenium and a half, and I'm a bit stuck on a section of worldbuilding (literally).

After the GM finally get the last person Processed, it gets to work mining the Solar System for the raw material to break down into component atoms and recreate as the ill-defined Unobtanium to build the main structure of the Ring. Now I've got two things to go on to determine the mass of this stuff. One was a mention of Quisling's Ringmetal collar, which Khan described to her as being both lighter than air and sufficiently tough that it would be simpler to cut her head off than cut through the material it's made of to remove it. The other is a throwaway gag in a drabble about the GM strip mining the Solar System for raw materials, including blowing up Pluto.

Okay, the lighter than air thing points towards Ringmetal being some form of Polymer Aerogel, maybe reinforced by handwavium carbon nanotubes. So, say whatever this stuff is made out of, it's got the density of maybe Helium. Now I have to figure out just how much this stuff is going to weigh when it's used to build a structure over 260,000 km in diameter, 1,000 km wide and 10km deep, bearing in mind there's going be dense and heavy machinery, soil, water, and air in the structure as well. [1]

Now the mass of the Asteroid belt, even including Ceres and the rest of the Big Four, is still less than half of Charon, Pluto's moon. Now given the total guesstimated mass of the Ring, would that be enough to build it, or would the GM have to sacrifice some of the crappier smaller moons of Jupiter and Saturn to fill things in?


[1] I'm guesstimating the soil and rocks will go down to a depth of one, maybe two kilometers, and perhaps five for the deepest part of the Ring Seas.

Comments

[seawasp]

I don't believe the lighter-than-air thing. Maybe the COLLAR was, by simply putting a vacuum inside a sufficiently thin enclosure of "Ringmetal", but you're not going to get that level of strength with that level of low density.

Strongest still-atomic-based material I have ever encountered even theoretical discussion of is ring-carbon, which I use in Grand Central Arena. This is basically taking carbon rings and interlocking them like chainmail (rather than the edgewise assembly you see in buckytubes, etc). To give you a comparison, perfect SWNT (single-walled nanotubes) of carbon have a theoretical tensile strength of 30,000,000 (3x10^7) N/cm^2, though that's PERFECT -- no flaws anywhere in the matrix. Pure ring-carbon has a theoretical tensile strength of 1x10^15 N/cm^2, or about a hundred million times stronger than perfect SWNT carbon. A ring-carbon composite would still have a theoretical tensile strength of 1.3x10^12, which is still a hundred thousand times greater than SWNT. It's that tough because deformation is resisted not only by the normal molecular bonds, but by the mutual repulsion of the shared electron clouds around the rings.

At a rough guess I get a mass for your Ring of 4x10^19 metric tons, assuming an average density slightly less than that of Earth (5g/cm^3 instead of 5.51) That's somewhere between 1/100th and 1/1000th the mass of Pluto.

[jeriendhal.livejournal.com]

That's somewhere between 1/100th and 1/1000th the mass of Pluto.

Oh, good. So disassembling the solar system isn't necessary. ;p I think I'll leave Ceres alone for sentimental value, and go ahead with pulling Lysithea from Jupiter's orbit. It'll be a high energy cost to pull it out, rather than moving a stray asteroid, but has the advantage of simplicity from the GM's POV in that it only has to move one moon for the Ring's mass, and grab a few comets for the Ring seas.

Hmm, would you consider ring carbon public domain enough for me to borrow, or should I just have someone note that the Ring had to be made of materials previously only thought theoretical?

[seawasp]

Oh, I found it in an online source, and not a copyrighted/patented one, so it's perfectly public domain. You could acknowledge me as your source for it if you like.

[jeriendhal.livejournal.com]

Thanks! I shall.

[allah-sulu.livejournal.com]

Or, if the humans ask what the walls are made of, the Groupmind can just tell them "None of your business."

[jeriendhal.livejournal.com]

Nah, the Groupmind would tell them. It hates cheating. :)

[allah-sulu.livejournal.com]

I would imagine the GM would have to keep some details secret, to make work harder for human hackers and saboteurs.

EDIT: I just picked up the first FYS collection on Amazon -- either you didn't post all of them to LJ beforehand or I missed a couple. Did the sales figures you posted the other day include the audiobook? Any likelihood of further audiobook adaptations?

[jeriendhal.livejournal.com]

The GM would probably feel safe enough giving the formula out, knowing that human don't (normally) have access to the level of industrial nanotech to create that sort of material.

And if they somehow did, it might let them work on it for a while, just because it'll keep them occupied instead of doing something more destructive.

As for the book sales, I left out the audiobooks. Total sales for the past year and a half have been 43 units. If I hadn't done the Kickstarter I think it would take a decade or more to make my money back the way Audible plays with the pricing structure. :( I honestly don't see another one happening again unless I read it myself (and my reading voice sucks) or do another Kickstarter, which would be a pain in the ass. :(

[allah-sulu.livejournal.com]

That's too bad. I heard the audiobook before I read any of the Red Vixen books.

[allah-sulu.livejournal.com]

Given those dimensions, the total volume of the Ring* is about 8,136,724,972.798 km³.** However, given that the Ring is hollow, you'll need to explain how thick the walls are in order to calculate how much Scrith is required.

Much of the interior will be water and air, which can be minded from the gas giants with scoop ships. You'll only need to break down asteroids and dwarf planets for the walls and machinery. As for soil, some of the materials required for that (e.g. nitrogen) can also be scoop-mined from gas giants; and it will have to be processed from crushed rocks, sand, and dust into living soil by microbes, algae, earthworms, and the like before it can support an ecosystem with higher organisms -- which will probably be a good portion of the time required to set up the place before the plants can grow and humans and animals can be revived.

*I calculated the volume of a solid cyclinder 260,000 km across and 10 km high; then I subtracted a cylinder 258,000 km across and 10 km high to just leave the Ring.

**The total volume of Pluto is approximately 7,005,526,273.1586 km³, given a mean diameter of 1,187 km and 4/3πr³. Not enough material to make the Ring if the Ring were solid, but possibly enough to make a hollow Ring and the machinery inside if the rest (gases and liquids) are mined from Jupiter and Saturn.

[jeriendhal.livejournal.com]

The Walls are 1 km thick. I figure they're 50 km high to hold in the atmosphere, with the Roof atop them. Of the 10 km thick Floor, lets say the top 1 km is rocks and topsoil, an additional 4 km relatively hollow, with machine works supporting Ring operations and manufacturing, separated by the Ring Seas, the next layer down solid Ringmetal, and the final 1 km on the underside supporting docks, ventral solar collectors, and the OMS.

Yeah, grinding the rocks down to soil would be a long term project, with or without worms. May have to skip the majestic Redwood forests, at least for the first millennium or so.

[allah-sulu.livejournal.com]

Humans on the Ring taking their grandchildren to visit the majestic redwood saplings. "Trust me, when you take your grandkids here, they'll be impressed."

(Similar joke happened on The Flintstones once, when they went to visit the Grand Canyon, which was just a small ravine at the time.)