Relevant xkcd: https://xkcd.com/1758/ https://xkcd.com/1758/ Dark matter really is a theory with falsifiable data. I'm not sure of the exact arguments, but I b

Relevant xkcd: https://xkcd.com/1758/ https://xkcd.com/1758/ Dark matter really is a theory with falsifiable data. I'm not sure of the exact arguments, but I believe the evidence available (such as the evolution of galaxies) is only consistent with the existence of actual dark matter particles, and not with some alternative explanation of gravity. It's not as simple as saying the mysterious properties of the hypothetical particles are defined solely by our observation, because simply assuming the existence of these massive particles explains all the experimental data within our current framework of gravity, while no other theory has successfully explained the data. We don't need to invent any mysterious new properties beyond the properties that we know massive things have. So yes, maybe we will one day discover that dark matter isn't real. But by Occam's razor, it seems very likely that it's real, and nobody has a better idea. If it is the only theory that fits all the data, there doesn't seem to be a good reason to reject it.