Dark matter seems to have the upper hand at the moment, at least with what I read. But now I keep hearing about Modified Gravity Theory as a alternative explanation for the large structure of the Universe, (often paired with comparisons between Dark Matter, and what was once called the "luminiferous ether"). How much support has MGT garnered at this point? Is this a serious point of view, or something that belongs more in the "debunking" section of the forum? What has been "modified" with respect to gravitational theory?