  We present a toy model where spacetime is emergent from a more fundamental
microscopic system, and investigate the gray area interpolating between the
collective and free-particle regimes. For a period of rapid exponential growth
in the analogue universe, we argue that the intermediate regime is best
described by a coloured potpourri of geometries -- a "rainbow geometry". This
can be viewed as an alternative approach towards understanding quantum field
theories in the presence of Lorentz-symmetry breaking at ultraviolet scales.
Firstly, it is pointed out that cosmological particle production in our
emergent FRW-type analogue universe, when compared to conventional
semi-classical quantum gravity, is only temporarily robust against
model-specific deviations from Lorentz invariance. Secondly, it is possible to
carry out a straightforward quantitative analysis to estimate a suitable
parameter regime for experimental (analogue) cosmology.
