The existence of a “luminiferous aether” would have no observable consequences unless there was some kind of force or field that was not governed by laws that are locally Lorentz covariant. But so far nothing of that sort has ever been detected. So, as Pierre-Simon Laplace famously responded to Napoleon Bonaparte after Bonaparte expressed surprise that God was not mentioned in Laplace’s manuscript, we “have no need of that hypothesis”.
Source: (1001) Alan Cooper’s answer to Ah but what if there is a luminiferous aether? – Quora