because here's something, you leave it there,

因为你把一个物体放在那里
it doesn't move.

自己肯定不会动
It's not a big surprise."

所以没什么大不了的"
People were used to that from the time of Aristotle.

亚里士多德时代的人们觉得这很自然
But Aristotle used to think that if you want something to move,

但亚里士多德认为如果要让物体运动
there has to be some agency making it move.

那就必须有某种作用让它运动
That agency you could call force.

这种作用你可以称之为"力"
The great discovery that Galileo and Newton made is that

伽利略和牛顿的伟大发现就是
you don't need a force for a body to move at constant velocity.

物体不需要力来维持匀速运动
It's very clear you don't need a force

显而易见如果物体没有运动
if something is doing nothing, just sitting there.

只是静止状态那是不需要力的
The fact that you don't need a force for it to move forever

对于物体不需要力的作用就能保持