He is describing the difference that exist in dynamical systems (physics, computer systems) between microscopic and macroscopic descriptions. If you have few i

He is describing the difference that exist in dynamical systems (physics, computer systems) between microscopic and macroscopic descriptions. If you have few interactions among things, you can analyze their interactions through the lenses of cause and effects. That's the microscopic part. Think about a snooker table, if it's normal sized and a normal number of balls, you can imagine more or less what will happen once you hit your ball. Once you have many things that interact between each other, with each interaction going in different ways, tracing causal links becomes impractical. Things start to get "chaotic", in the sense that small variation can cause long term changes in their trajectories (this can happen in any system with 3 or more degrees of freedom and feedback, because 3rd degree differential equations can have two curves/solutions that coincide on one side and then bifurcate later). Given enough things, it is like playing snooker with an infinite table and infinite balls, and infinite players. Then it start to make sense to track the macroscopic values that are conserved in large parts of the infinite table, e.g. energy levels of the balls (kinetic) and the force and general direction with which each average player hits the balls (acceleration). Does this help?