"We've closed this loophole about gravity, and we've come closer than ever to seeing this invisible matter," Clowe said.
I would not bet my inheritance on that.
Physics theories of the late 19th century postulated that, just as water waves must have a medium to move across (water), and audible sound waves require a medium to move through (air), so also light waves require a medium, the luminiferous aether. The speed of light being so great, designing an experiment to detect the presence and properties of this aether took considerable thought.