It's really just random collisions pushing the molecules apart, thus making them spread out in every direction.

这实际上只是随机碰撞将分子推开，从而使它们向各个方向扩散。

The center of this disk is where the Sun was born, and it's thought that the planets formed as smaller particles of material stuck together during random collisions farther out in the disk.

这个圆盘的中心就是太阳诞生的地方，其他行星被认为是由较小颗粒物质在圆盘外因随机碰撞而聚合形成的。