translation.en: But if we were freely falling through the space, even without this helpful grid, we might be able to paint it ourselves, because we would notice that we traveled along straight lines, undeflected straight paths through the universe.
translation.zh: 但如果我们在宇宙中自由落体， 即便没有这些辅助线， 我们的轨迹也会画出这些线， 因为我们将会发现我们沿着直线运动， 沿着不发生弯折的直线 穿过宇宙。