Cosmic acceleration with cosmological soft phonons

The dark energy scalar field is here presented as a mean-field effect arising from the collective motion of interacting structures on an expanding lattice. This cosmological analogue to solid-state soft phonons in an unstable crystal network is shown to produce cosmic acceleration while mimicking phantom equation of state. From an analysis of the Hubble diagram of type Ia supernovae, we present constraints on the parameters of the cosmic Lagrange chain, as well as on time-variation of the soft phonon equation of state, before we conclude on new phenomenology associated to this interpretation.