Talk:Fluctus/@comment-194.66.83.42-20150805085935/@comment-73.188.65.207-20150809203200

That's not how space works. In space, you still have mass, when you still have mass, you still have inertia. This means that to move something more massive than another, you require more force, even in space. Yes, in space (not taking into account freefall or attraction via gravity), when given a certain amount of force, that object will continue in the direction of the force given, (assuming it doesn't run into any other objects), but the more mass that object has, and thus inertia, the more force you'll have to extert to make it travel at a certain speed. If you want to stop, then you have to extert that same force in the opposite direction. This means that even in space, with large ass guns, you'll still need to account for their mass. More mass=more energy expended moving them.