Gravity waves in General Relativity
are required by imposing the speed of light as a limit to the speed of response of the bending of space to the movement of a mass in space-time. This is also why equations in general relativity are so recursive.
Van Flanderin postulates that such propigation effects are through longitudinal wave propigation in space time, and uses models that go back to the original Maxwell equations that used a 2 tensor convention called quaternions. He states that not having found gravity waves generated by this delay in response is evidence that gravity propigates faster than light.
What was known until 1983, as Maxwell's equations was the 4 tensor equations that were simplified by Hertz and Heavenside, from Maxwell's original work. Unfortunately this has been taken up by fingers who assume that such longitudinal waveforms always occur and they use the term Tesla applied to such waveforms when he was still learning the English language: scalar waves, which leads to total nonsense, especially since Tesla thought he had to continue using his original term.
Hawking postulates a general variation of time that is orthoganal to out usual time dimension, that uses the j operator, to sort out time reversed elements. See the later chapters of his A Short History of Time and Space
Hikau and Thorne apply quantum mechanics directly to space-time structures to create a sort of quantized either that has multiple possibilities for how gravity waves interact. They have models that both do and do not require that gravity involve any sort of quantum of gravity or graviton. In superstring theory this involves what is now known as the membrane hypothesis, based on whether quantum effects do or do not involve uncertainty in the fabric of time-space itself, and is at this point in time arbetrary. Such concepts do however modify the post given by quark in that there is a big difference between saying that quantum mechanics does work without any hidden controlling elements, while quark stated that the assumption of there being no hidden controling elements is a religious one.
One pointer to the membrane hypothesis being true is the evidence of the vector-Bosons which are super heavy quanta involving the coupling of mass between the bending of time-space and the fact that most particles have mass. In words, the vector-Bosons are the quanta that carry the action of space having been bent by usual mass and the usual characteristics we assign to mass such as inertia. In that vector-Bosons can be considered to be sections of space-time/either that form real particles, by this super-dense space-time foam/either being ripped into pieces by strong energy interactions, and thus appear as quanta for the coupling of the usual effects of mass, from the time space foam/either.
Another pointer to the possibility that space-time itself is subject to quantum fluctuations, going beyond the assumptions of special relativity and Planck's constant itself, is the manner in which elements in Einstein-Bose condensates exhibit even-odd behavior of their Fermion number. Odd number nuclei exhibit properties of single particles subject to Pauli exclusion, while even number nuclei act as if they were single particles such as photons that are not subject to Pauli exclusion.
In all of the above there is reason to question Einstein's model of gravity being a psuedo force that is purely the result of the interaction between objects with mass and 4 dimensional spacetime and the evolution of attempts to measure intervals of Minkowski invariants as your time changes.
In all of the above it is likely that some elements of Maxwell's original Quaternion equations will be used to simplify a restoration of Longitutinal wave propigated effects.
It is not a flaw, but there is incompleteness in Einstein's Theory of General Relativity.