I'm curious about this. I saw this:
and they're suggesting that as direct searches for dark matter more and more continue to come up empty, while the gravitational observations persist, that the possibility arises that perhaps dark matter might not exist after all, and that continued hope that it exists and will be found in the next search more and more becomes a possible case of confirmation bias or special pleading, suggesting that instead some form of modification of gravity would have to be responsible (if not something else altogether).
However, what I'm curious about is the following:
- Is there any modified gravitational idea available that can parsimoniously account for the "tricky" observed phenomena like the Bullet Cluster and diffuse dwarf galaxies like NGC 1052-DF2 that seem to suggest the gravitational effects behave as separate matter, as well as all other suggested astronomical DM evidence, to within the margins of experimental error? As the impression I had was that modified gravity theories were getting more and more contrived,
- What sort of astronomical observation could distinguish between a modified theory of gravity and, say, actual dark matter that is "super dark", i.e. it ONLY interacts gravitationally (not a logical impossibility!), or at least so that any interaction it does have other that gravitation requires some ungodly high energy scale like near-Planck level to observe and thus will be forever inaccessible to direct experiments unless, perhaps, eons from now, if we or some AI or otherwise evolved descendant of us, if any exist at all, could do astronomical-scale engineering petaprojects involving petameter-scale particle accelerators capable of Planck-scale collisions? :)