So, IMHO, author should replace "ripples in water" with something scientific, e.g. "ripples of space-time", "ripples of fabric of pond", "excitements of pond field", because now his text makes reader feel like there is water in the pond.
End of trolling.
> In particular, the problem with aether is that it was a non-relativistically-invariant medium (that is, by moving, you could change your speed with respect to the medium).
Yep.
> Whatever light and gravity travel in is relativistically invariant,
LIGO demonstrated that c in vacuum ≠ const, thus they are not.
By the way, medium can change it speed too, it's not a static thing, so theory of relativity can be extended to include medium, which may solve some problems with QM and with experimental observations.