It looks like a tautology because you're never able to show me something that moves forever at a constant velocity, because every time you don't find such a thing, I give an excuse, namely, a force is acting.
这听上去像个死循环,因为你不可能,找到永远匀速运动下去的物体,因为每当你找不到这样的物体时,我就会给出一个理由,也就是,有力作用在上面
耶鲁公开课 - 基础物理课程节选
