这当然不错。不过，一个物理学家会过来，他会向你展示，你永远也不会碰撞上任何东西，即使你用你的脑袋猛地撞上了一道石墙，你也不会真正地碰上它！

This is all very well, but the physicist comes along and shows that you never bump into anything: even when you run your head against a stone wall, you do not really touch it.

youdao

在碰上或撞上某物之后跳回或弹回。反弹。

To spring or bounce back after hitting or colliding with something.

youdao