Because diffusion is completely free movement, calculating the motion of individual particles becomes even more complicated.

因为扩散是完全自由的运动，计算单个粒子的运动变得更加复杂。

This is the epoch, when the only remaining energy in our universe, is generated due to the decay of protons and the annihilation of individual particles.

这是一个新时代，是由我们宇宙中仅存的能量是由质子的衰变和单个粒子的湮灭而产生的。

VOICE OVER: This change in properties is a kind of phase transition, from flexible or flowing to stiff and rigid, and it happens when the individual particles jam together.

画外音：这种特性变化是一种相变，从柔性或流动到僵硬和刚性， 当单个粒子挤在一起时就会发生这种情况。

The net velocity of a gas in any one direction will always be lower than the average velocity of its molecules because the overall motion of the gas is hindered by collisions among the individual particles.

气体在任何一个方向上的净速度总是低于其分子的平均速度，因为气体的整体运动受到单个粒子之间碰撞的阻碍。

The individual particles in a gas never move at exactly the same speed or direction for very long, instead, they bounce around like crazy, bumping into the walls of the container and each other over and over.

气体中的单个粒子永远不会以完全相同的速度或方向移动很长时间，相反，它们会疯狂地弹跳，一遍又一遍地撞击容器壁和彼此。