| Abstract: | The presence of Bragg scattering is a sufficient indication of order in solids, but is it necessary? I will discuss several examples of solids with perfect underlying order, yet no Bragg peaks in their diffraction patterns. I will give an alternative definition of order, one that catches the order of traditionally ordered systems, with Bragg scattering, such as crystals and quasicrystals, as well as the order of these novel systems. I will discuss the realizability of these systems and their statistical mechanical properties |
