Thread: Birch World
View Single Post
Old April 5th, 2021, 10:46 AM
Werner Werner is offline
Citizen: SOC-13
Join Date: Sep 2020
Posts: 724
Gallery : 0
Werner Citizen+Werner Citizen+

Originally Posted by BackworldTraveller View Post
As I said, the gravity profile isn't what you'd expect.

Earth has a column of material under each point that is treated as (on average) 6370(ish) km away.

Birch has a tiny column of material very near followed by empty space followed by another tiny column of material at 0.96 LY away. Gravity directly towards the centre is thus tiny at any point. How the vectors for every point add up to act on any other point I don't know but it isn't the same as a solid body. 50% of the mass is over 0.48LY away and is acting at an angle. Nearby mass is mostly pulling sideways and doesn't exactly offset the far points because of the variation in distance.

Spinning the surface at something near C means that any incoming particles are incoming at near C. That makes them very dangerous to life!

The circumference is almost exactly 3 light years. Which means that centrifugal force experienced is about 0.5m/s2 (relativistic effects not calculated).

A sphere will be in trouble because the poles have no centrifugal force and thus fall towards the centre. Here they quickly exceed the mass required for a black hole to form. And the whole thing then collapses.

The great circle has the mass of 1,523,909,050,200.7/2 suns spread along a line 3LY long. That is .000027 MSol per metre. More than enough to make any material malleable. So the radius slumps, collapses and...big black hole.
For one thing the Universe this Birch World exists in is extremely old, the builders of this world had to gather the materials of over a thousand galaxies when this universe was much younger, as they foresaw the end coming, they knew the stars would not shine forever, this Universe is hundreds of trillions of years old, maybe quadrillion of years old. Anyway when this Birch World was built the universe was much younger, they created a void buy mining out local galaxies until there was nearly nothing left, since they built it, those living on its surface were under its gravitational time slowing effects, so maybe for every year spent on the Birch World one thousand years pass for the external universe and this universe just keeps on getting bigger, darker, and emptier, there are black dwarfs out there. The Birch World has billions of years supply of hydrogen and other light elements to run its fusion reactors and with gravitational time dialation that is trillions of years passing in the external universe, escaping the gravity of the birch World requires an antimatter drive and once out there, there is not much, a few black holes. The birch World builders had little use for those stellar sized black holes, as they couldn't build anything out of them.

There is little reason to rotate the birchworld anyway, parts of it spin to counteract the pull of gravity, but not the whole thing. Having gravity is kind of the point. The surface gravity is 9.81 meters per second squared, the escape velocity however is nearly the speed of light. One can go above the atmosphere of course, but it takes continuous thrust to stay up there. As for whatever engineering magic is required to keep this structure stable, I leave it to minds far more ancient and smarter than my own. You just have to take a leap of faith that this thing is possible, just like you do for artificial gravity generators and the Jump drive.

As for the Jump Drive itself, it just won't work anywhere out to a radius of 100 light years, so they are pretty useless, inside the shell is another story, you can make a jump from 12,800,000 km inside the shell to the star system in the center. Inside this shell is flat space, you can jump to any but the innermost planet in the star system, or from there back to the shell, in each case the Jump will take one week in Jump space. Perhaps the PC's have misjumped their Starship and ended up in this strange and ancient parallel universe. At the center is a model of Earth's Solar System, it is not certain whether it is the original Solar System or just a copy. All the planets are there from the Sun all the way out to the Oort cloud, there is Earth, the continents are in an unfamiliar arrangement, the Sun looks to be 5 billion years old, it is clear that this birch world was built by the descendants of humans. There are the images of stars projected on the inside of the birch world shell, its surface reflects radar, so its nature is obvious to the right detection instruments, to the naked eye it just looks like normal space, so any PC starship that ends up trapped here will become immediately familiar with the situation once they attempt to jump out of system. Naturally the Birch world builders left a device that could send the PC's starship back where it came from, they just have to find it.
Reply With Quote