The concept of cold dark matter is only based upon the need to explain observations that are not in agreement with the expectations based upon Newton’s gravitational constant. In the standard theory of the universe, the missing gravitational effect is supplied by supposing that it provided by additional mass that however is invisible – thus dark matter is invoked but it is only detectable by gravitational effects.
However, the observations and theory can be reconciled if one generalizes the gravitational constant as a power series in distance r. The additional component of the gravitational constant is still valid in our solar system (where the observations of planetary motion was used by Newton in his theory) and becomes significant at distances about the size of galaxies.
Details are available at my web site http://inventing-solutions.com/simplified-universe.htm
When the material in my site is taken into account, the excellent work by physicists trying to explain dark matter, dark energy, and other mysteries will require significant reevaluation.
My site is intended to help avoid wasted efforts of professionals working to understand the universe.
Additional material will be added as time permits.
Contact me with questions if you wish.