What space to simulate the physics bodies in. This affects how velocities are generated. Options include: Component Space: Simulate in component-space. Moving the entire Skeletal Mesh will have no effect on velocities. World Space: Simulate in world-space. Moving the Skeletal Mesh will generate velocity changes. Base Bone Space: Simulate in the selected Base Bone's bone-space . Moving the entire Skeletal Mesh and individually modifying the Base Bone will have no effect on velocities.