 So how do you calculate situations when you just have so many atoms you can't follow them all one at a time? Well, if all the atoms are moving along at the same direction at the same speed Then that's just like throwing a ball and you can calculate things using Newton's laws If on the other hand, they're all just moving totally at random In that case we treat it as heat and we can do statistical things with all the random motions as we'll see in a bit Which gives us a whole lot of ways to calculate things also very useful We could also combine them so we could talk about a hot ball being thrown and we'd combine this random motion with that Just add the two together There is however a really irritating situation where you can't quite do that Which is something like this where things are almost but not totally random At first glimpse here the particles are going all over the place But if you look closely you'll see the ones on this side are moving down and the ones on this side are moving up And this is what we call turbulence It's motion that's too small scale and chaotic to follow every little bit of the fluid But it's also still much more ordered than just temperature motions And it's a really difficult thing to calculate and it's currently a major research area We won't talk about it further in this course