I thought that I should layout my plan for research in the near future. Part of my research for my senior thesis included looking into a way of explaining flat rotation curves without including dark matter as a generating gravitational potential. I was looking into a claim that by using GR the flat rotation curves could be reproduced without including dark matter as a correcting term. While the particular method I looked into had some problems there was one paper that I stumbled across that showed that using GR they could give a slight correction to the rotation curves before they needed to include dark matter.
In conjunction with this there was a paper published by several astronomers giving a correction to the amount of normal baryonic matter present in a galaxy. They did this using surveys of the number of face of galaxies versus the number of edge on galaxies and saw that there was a discrepancy, there were more face on than edge on. Thus they concluded that there must be more dust in the galactic halo than they previously thought. This added another correction to the mass, and the assumed amount of dark matter, in a galaxy.
So my plan is to take all these corrections and add them up and see if it amounts to a significant correction to the amount of dark matter that must be present in a galaxy. If this holds then it will also add a correction to the amount of normal and dark matter in galaxy clusters. This will additionally change everything else.
There is also a theory out there that attempts to explain dark energy in a new way. Essentially the argument goes that we might actually live in a "cosmic bubble" of low density space. If this were true then it would create the illusion of an accelerating universe. So it would be possible to explain what we see in terms of what we already know instead of making an appeal to some unknown type of matter. The idea that lead to the introduction of dark energy was the Copernican idea that the universe is for the most part homogeneous, that is, where we live does not have any unique properties that makes it different from the rest of the universe. This idea continues on with the statement that the universe is homogeneous on a large scale.
But what if there is some local inhomogeneities? This leads me to think of another guiding principle. Always try to explain what we see in terms of what we know, without making an appeal to some unknown stuff with unknown properties. What we know is stronger than what we do not know. A known is (almost) always a better explanation than an unknown. So if we make an assumption that leads us to conclude that there is something unknown governing the universe and determining what we see, then perhaps we need to rethink that assumption or how we are applying that assumption.
So I plan to investigate these things and see if I can't make sense of what we see in terms of what we already know without making an appeal to things unknown.