Question

What is long range order

Answer 1

One often encounters the statement that ordinary isotropic liquids are disordered, something which is not entirely true. The average distance to the nearest neighbor of each molecule (or other constituent of the phase) is actually quite well defined, a fact that distinguishes this least ordered condensed phase from the gaseous state, which is truly disordered. However, the distance to the next nearest neighbor is much less defined and over longer distances the correlation between molecule position is very poor. We say that the correlation length is short or that the liquid is only short-range ordered.