So, massless bodies will always have, like a massless rope, equal and opposite forces on the two ends.

所以无质量的物体,比如这个绳子,两边所受的力永远都相等

耶鲁公开课 - 基础物理课程节选

Yet even there, when I imagine an eternity of thinking about math--or for that matter, an eternity of thinking about philosophy, which I obviously like even more than math-- the prospect seems an unattractive one.

即使如此，当我想到让我永远,思考数学问题，或者说，让我永远思考哲学问题，显然和数学相比，我更钟情于它-,但这个提议也变得无趣。

耶鲁公开课 - 死亡课程节选

Somehow, if you could manufacture a really smooth frictionless surface, that if you took a hockey puck or something and an air cushion and you give it a push, in some idealized world, it'll travel forever.

如果你制造一个绝对光滑无摩擦的表面,然后在上面放个冰球或者别的什么,或者气垫,然后推它一下,在理想条件下,它会永远运动下去

耶鲁公开课 - 基础物理课程节选