Most likely candidate for dark matter?
I have read into some depth about the various candidates for dark matter, the merits and flaws of each.
I don't know of any merits for WIMPs.
However what I have been unable to attain from texts alone is what is the most likely explanation of dark matter right now? Obviously, some are more likely than others, but at the present day, which ones 'seem' to be the most likely based on the contributions to them at the present.
IMHO when you understand general relativity you will appreciate that the most likely explanation for dark matter is space.
I am going to be writing an EPQ and wish to focus on the most likely theories, as there are too many to go over them all.
General relativity is a likely theory. In fact it's just about the best-tested theory we've got. See Clifford M Will's confrontation between general relativity and experiment. Also see Einstein's Leyden Address where he described a gravitational field as space which was "neither homogeneous nor isotropic". He also said this "has finally disposed of the view that space is physically empty". Space is a something rather than nothing. The crucial point is in The Foundation of the General Theory of Relativity: "the energy of the gravitational field shall act gravitatively in the same way as any other kind of energy". That's spatial energy causing gravity, and it isn't made up of particles. Whenever the energy-density of space is not homogeneous, there's a gravitational effect. Why this isn't common knowledge, at least amongst physicists and cosmologists, I just don't know.
You'll be aware of the raisin cake analogy and conservation of energy, so you can appreciate that space expands between the galaxies, but not within the galaxies. So every galaxy is embedded in space with a higher energy-density than the surrounding space. So there's a gravitational effect, and it isn't caused by matter. See Inhomogeneous and interacting vacuum energy and Inhomogeneous Vacuum: An Alternative Interpretation of Curved Spacetime. They don't say space is dark matter, but they do say space isn't nothing. Remember this:
Space has its vacuum energy. When it's inhomogeneous it has a mass equivalence and a gravitational effect. And space, of course, is dark.