I've always figured there must be a simpler explanation for the observed lack of red shifting that has lead astronomers to hypothesize Dark Energy. Or at least there must be a simpler explanation of Dark Energy than an ever-increasing amount of energy that pushes the universe apart.
However, now that we observed the GW170817 event in two independent ways, does this confirm that Dark Energy exists, or is there way too much uncertainty to use it to make inferences with?
Although light is often said to be weightless this is simply not true because photons have momentum and therefore bend spacetime. I had hypothesized that at a quantum level the photons could interact with their own gravitational bow wake in such a way as to stretch the waveform out, possibly while destructively interfering with the waves in front and behind it, thus making it appear as if the energy had been stretched out over time.
However, now that we have observed a gamma-ray burst from both the light and the gravitational waves emitted, does this disprove the idea that gravity could be the cause of the redshift?
An alternative explanation to both Dark Energy and my hypothesis would be that dark matter or something else in the galactic medium, just has a red shifting effect on light waves.
But if both the gravity wave and lightwave diminished in intensity exactly as expected, and that nothing affected the light that didn't affect the wave; wouldn't that then prove that they were in fact just as far away as we expected them to be? I doubt that we have enough information to make such expectations, but if so I might have to start accepting Dark Energy.
EDIT: Originally, I had said extra redshifting instead of lack of, but I've since realized that if universal expansion appears to be accelerating, then more distant objects have slightly less red shifting then what would be expected of them.