imagine that the polymer can be reg

imagine that the polymer can be regarded as a string of N units.
Each unit is joined to the next by a perfectly flexible joint, like a string of paperclips.
In thermal equilibrium, the joints will all be at random angles.
An instantaneous snapshot of the polymer will be different at each instant of time, but there will be a family resemblance in a series of such snapshots: Each one will be a random walk.