### It's a gaming geek post!

Aug. 2nd, 2008 05:28 pm*Magic: The Gathering*, when Douglas Adams wrote games for Infocom and no one had ever thought of writing a second edition to

*Advanced Dungeons & Dragons*, a friend and I -- well, mostly my friend -- published a

*Traveller*fanzine. I was so young I barely knew how to perform calculus, and certainly didn't know

*why*; and so one day I conceived the idea of deriving the kinematic equations of jump space.

It's been many years since I last played

*Traveller*, so don't quote me on the details, but "jump space" was the macguffin which allowed faster-than-light travel. All jumps took exactly one week, regardless of how far you travelled; bigger ships with bigger jump drives could travel farther; and the upper limit for jump distance was six hexes. If you tried to jump seven, your ship would be lost forever. So I sat down with these constraints, wrote them out as boundary conditions for a set of differential equations (not that I knew this terminology at the time), and derived some equations of motion which led to precisely this behaviour.

Jump space, I wrote, was an orthogonal spatial dimension to our primary three spatial dimensions. A force analogous to gravity operated within this space, pulling any mass "down" toward our dimension -- where some unexplained contrary force balanced it exactly, just as the pressure of the planet beneath our feet balances the force of gravity. Matter tends to stay in our universe just as most heavy objects tend to stay on the ground.

It so happens that if you throw a ball on the moon -- in the presence of gravity, but without any frictional forces to slow it down -- it will keep moving horizontally at a constant velocity, while gravity acts on its vertical velocity. Once it hits the surface, it meets other matter to interact with, which will usually stop it from moving horizontally too. I hypothesized that something similar happens in jump space. If you enter jump space with a particular normal-space velocity, you'll retain that velocity throughout your travels in the jump dimension, because there isn't any ordinary matter on which you can get purchase to change it.

And so I calculated the field equations for a force which would return matter to normal space in a constant time, but which (above a certain threshold) wouldn't return it at all. They were just numbers, with no geometric basis for articulating

*why*they worked in physical terms -- but they agreed precisely with the physical observations written up in the

*Traveller*rule books.

By the time I was done, I was really very impressed with myself. I was the princess of RPG geekdom! I could do anything!

And so for my next trick, I decided to come up with a scientific basis for the

*Dungeons & Dragons*magic system.

**( It's still the best magic system evar. )**

By publishing this magic system on my LJ, I am also releasing it into the universe under a Creative Commons licence. Anyone can use it, or vary it, for free, but in the unlikely event you plan to make money by selling it, I want a cut.