What is the thrust limit of Psychokinesis? You could lift the ships out of the gravity well using a verity of magics. Then you could use Psychokinesis to (very, very) slowly accelerate indeffinately. In zero-g a spirit with a Psychokinetic strength of 12+ could barely move a mega-ton ship, but they could just keep on keeping on until they reached whatever speed you wanted. Also think about how much redundancy you could remove with Guard.

I'm imagining huge biosphere/ arcano-ships on interplanetary orbits with nano-fabs cranking out SOTA mining and construction drones and droppping them off all over the solar system.

Correct. That's already been hashed out here plenty of times. Movement is a handwavy time-dilation effect that somehow makes things move faster but yields no increased inertia (no super bullets, spaceships slow back down instantly once Movement is dropped), but yet also yields no increased IPs, Perception bonuses, or anything else that you'd expect from time dilation.

It multiplies velocity without doing *anything* else. Which makes no sense at all, unless you're trying to keep a useful game concept from becoming a game-wrecker.

You ever see any of those horror movies where the evil critter or ghost suddenly 'pops' forward by a couple of feet without moving? I think it happened near the end of The Ring, by way of reference...

I've always run Movement working like that. The extra distance you're covering is basically just short range little 'blip' jumps in space. Because that's the only way I could rationalize vehicles not burning up and exploding when they get movement used on them, or a movement-affected street sam not wearing his shoes out in a hurry.

I take the rules of the Movement Power as a simplification of a complex vector addition formula.

The basic idea is simple. If your walking along the a flat ground at a constant velocity then your velocity can be measured as <a,b>, a 2D vector. However, what if this ground is a conveyor belt and as you walk along it it starts moving. Your velocity relative to the conveyor belt will still be <a,b> but your velocity relative to things not on the conveyor belt will be <a,b> + <x,y> where <x,y> is the velocity of the conveyor belt.

Now, let us assume that you are moving along with the conveyor belt in the exact same direction as the belt. In this case, it will be true that <x,y> = S<a,b,> where S is a scaler.

From this we can derive :

<a,b> + <x,y> = <a,b> + S<a,b> = (S+1)<a,b>

In regards to the movement power, S always equals (M-1) where M = the critter's Magic.

Thus, V= M<a,b> is the simplified form for the Movement vector addition equation.

This can again be expanded to (M-1)<a,b> + <a,b> = <x,y> + <a,b>
Thus <x,y> = <(M-1)a,(M-1)b> = <Ma, Mb> - <a,b>
Therefore
<a,b> + <x,y> = <a,b> + <Ma, Mb> - <a,b> = <Ma,Mb> = M<a,b>


Thus, you can see how the movement power is simple vector addition brought about by magical alteration of the terrain.

Acceleration is not altered because SR4 does not model acceleration at all. Objects and people in SR4 do not have rates of acceleration, they simply have Movement Rates, which are static velocities.

In dealing with movement in the atmosphere, this is not unreasonable. There are simply too many forces acting on a body to accurately model in an RPG such as this. And, honestly, I don't want to spend $80 on a 3000-page supplement consisting of nothing but drag and a friction coefficient tables.

In space, there are very few forces working on a body, so it is substantially more difficult to overlook fudging. However, the fact that space travel is so rare in SR makes the production of a realistic calculus-based movement model somewhat frivolous.

I hate you, Hyzmarca.
I read that and read it again, and read it a third time, and I know what it is that you're saying...I just can't read the form that you're saying it in.

I have 'incompetent: math", I swear.