Ising model

It is a mystery no more: A physical model can explain how a bunch of ants are able, with no visible leader (or highly-developed brains, for that matter) to drag that oversized cake crumb or leaf all the way across your floor to their nest. It turns out that there are, indeed, leaders, of a sort. Those ants you see surrounding the prize being hauled are switching places with other ants that have been scouting out the directions to the nest. The new ants then direct the collective movement, at least for a moment or so until they begin to lose their sense of direction and newer ants take over.…