These symbols put into math form what you have already seen in the pictures above. The symbols say, in a clear way, that you cannot be perfectly certain about where something is and where it is going. If you get clearer on where it is at any time then you have less of an idea on where it is going and how fast. If you get clearer on where it is going and how fast at any time, then you have less of an idea of where it is right now. 