# 引力是如何作用的？

## How does gravity work?

Gravity is a very important force in the natural world, and it is the result of the interaction between masses. According to Einstein's theory of general relativity, gravity can be seen as the curvature of spacetime, and objects move along the curves caused by this curvature. This concept can be explained using a classic example: imagine a ball placed on a sheet, which is curved by a heavier ball. When we place a lighter ball on the sheet, it moves along the curvature caused by the heavier ball. This is similar to the situation of objects moving in a gravitational field.

The reason for the gravitational interaction between objects is that mass produces a kind of energy that pervades the entire space. According to Newton's law of gravity, the gravitational force between objects is directly proportional to their masses and inversely proportional to the square of the distance between them. This means that objects with larger masses exert stronger gravitational forces on each other, while objects that are farther apart exert weaker gravitational forces.

Gravity not only explains celestial motions, but also explains physical phenomena on Earth. For example, we stay on Earth because it exerts gravity on us, keeping us firmly on the ground. Similarly, the Earth attracts the moon, causing it to orbit around the Earth. This gravitational force also explains why an apple falls from a tree, as the Earth attracts the apple, causing it to fall.

In summary, gravity is a universally present force in the natural world, and it drives various motions and changes through the interaction between objects. The nature and mechanism of this force play an important role in scientific research, allowing us to better understand and explain the phenomena we observe.