Quote Originally Posted by SiuiS View Post

That's why I specified that it was inconceivable; I couldn't tell you how it would work, but that doesn't mean I discount it as impossible.

I think the commodore meant negative movement specifically in this context. That is, even less movement than none at all. And you're right; the closest I can fathom of "negative motion" is motion or equivalent energy being displaced into a plane that doesn't count as motion. But that's kind of a cheap bye, and not a real solution.*
Personally I've always interpreted things that shouldn't have a negative value as draining that value from the surrounding area to keep it zero/positive. So something with a negative light value becomes a source of darkness as it drains light from the area around it, and an object with a temperature below absolute zero would start draining the heat from everything around it to keep itself at absolute zero. The lower the value, the wider the range of the drain.