Michelson–Morley experiment is best yet

Physicists in Germany have performed the most precise Michelson-Morley experiment to date, confirming that the speed of light is the same in all directions. The experiment, which involves rotating two optical cavities, is about 10 times more precise than previous experiments – and a hundred million times more precise than famous Michelson and Morley's 1887 experiment (MMX).

This zero result still cannot be interpreted as an absence of Aether environment for light spreading (so called luminiferous Aether), though. This is because no (motion/reference frame of) environment can be detected by its own waves locally, and nothing strange is about it. Whether we can observe water surface by water surface waves? Indeed not - with respect to these waves water surface is just a void, empty space. If we would observe something, it would be obstacle for surface waves, but not environment anymore. This is a trivial geometrical insight, independent to character of light wave and or even Aether theory validity: no local object can be observed from insintric and exsintric perspective at the same moment, i.e. locally.

This still doesn't mean, such environment doesn't exist from nonlocal and/or higher-dimensional perspective, mediated by tachyons, like gravitational waves, for example. And because every laser is of finite length, we should observe nonlocal effects, too. The true is, due the quantum phenomena no object is completely local and for microwaves of cosmic microwave background radiation (CMB) Lorentz symmetry would remain fulfilled even at the case, when these objects would remain relatively large - in distance/size range of CMB wavelength (~2,64 cm at 2,73 K black body temperature), which roughly corresponds human scale (size of brain waves). Therefore for CMB Lorentz and Poincaré symmetry remains violated only at the cosmological scale (Doppler anisotropy of CMB).

For photons of observable light we should detect gradient of CMB photons density (dark matter effect, dual to Casimir force) and Lense-Thirring effect (frame dragging effect) in proper orientation of laser perpendicularly to gravitational field gradient. The later effect will lead to antigravity effects at speed higher then 0,57 c, thus switching the sign of dark matter effect. Such insights renders warped space around moving Earth in rather complex way. The nonzero rest mass of photons would complicate result of MMX even more for light of shorter wavelengths. For example gamma ray photons are insintrically slow and they could be outdistanced even by lightweight part of observable matter (aka neutrinos), whereas photons of longer wavelengths, then the CMB are effectively tachyons and they undergo fast dispersion in CMB field.