On November 24th, 1951, Dirac published a letter in Nature, asking: Is there an aether? He argued based on his new electrodynamics theory that aether is necessary. He concluded his letter with the following words: "Thus with the new theory of electrodynamics we are rather forced to have an aether." See: http://www.fisicateorica.me/repositorio/howto/artigoshistoricosordemcronologica/1951b%20-Dirac1951b.pdf.
Before Dirac, Einstein himself remarked in his Leiden lecture (1920) that: "According to the general theory of relativity, space without ether is unthinkable..." (see http://www.spaceandmotion.com/Physics-Albert-Einstein-Leiden-1920.htm). Therefore it seems worth to reconsider aether, for instance there is a theory known as Einstein-aether gravity. An entry in wikipedia reads as follows: "...is a generally covariant modification of general relativity which describes a spacetime endowed with both a metric and a unit timelike vector field named the æther. The theory has a preferred reference frame and hence violates Lorentz invariant." (ref: http://en.wikipedia.org/wiki/Einstein_aether_theory)
However we know that Einstein-aether theory has limitations. For review of Einstein-aether theory, see: http://arxiv.org/abs/gr-qc/0410001.
So, do you think that aether is necessary both in electrodynamics and also in gravitation theory?