Probing cosmic expansion through small anisotropies in a Bose-Einstein condensate analogue

In this letter, it is shown that by measuring quantities like density variance in the present state of an analogue universe one can assess information about its history due to the mere existence of small anisotropies in earlier times, here modeled by non-uniform densities. This offers a valuable tool to probe and compare cosmic expansion models and, as an application, it is shown that quantum fluctuations can have a significant impact on the observable universe depending on its history.