And so this force of attraction, this is an ionic bond.

所以这种吸引力，这是一种离子键。

So, there is a gravitational force of attraction between every object.

因此，每个物体之间都存在万有引力。

For something like the Earth, you have to go really far away to not be affected by its gravitational force of attraction.

对于像地球这样的物体，你必须走得很远才能不受其引力的影响。

And the closer the asteroid gets to the planet, the stronger the field and the stronger the force of attraction it will feel.

小行星距离地球越近，磁场就越强，感受到的吸引力也就越强。

Now, the force of attraction between these two rocks is obviously very small, almost impossible to measure, and that's because the force is proportional to the masses of the objects.

那么这两块石头之间的引力显然是微乎其微，几乎是不可能测量到的，这是因为引力的大小和物体的重量成正比。

Well, the first scientist to really think about it was Isaac Newton back in the 1680s, and he said this, " Gravity is a force of attraction between all objects" .

首次思考这个问题的科学家名叫艾萨克·牛顿，他在 17 世纪 80 年代的著作中写道，“引力是一种存在于所有物体之间的相互作用力”。

If the student means to try the experiment of framing a dynamic law, he must assign values to the forces of attraction that caused the trouble; and in this case he has them in plain evidence.

如果学生打算尝试构建动态定律的实验，他必须给引起麻烦的吸引力赋值；在这种情况下，他有明显的证据。