EDIT> We can hand-wave estimates for the number of constituents in each of these systems. But it's interesting that we don't really know how many neurons there

EDIT> We can hand-wave estimates for the number of constituents in each of these systems. But it's interesting that we don't really know how many neurons there are in your individual brain, or in mine, etc. We can't yet look across the scales required to e.g. count and localize every single cell in your brain. Also, at what time? It changes. Just interesting questions when you get to a fine scale...