  The existence of the flat rotation curves of galaxies is still perplexing.
The dark matter paradigm was proposed long ago to solve this conundrum;
however, this proposal is still under debate. In this paper, we search for
universal relationships solely involving the baryonic density that incorporate
both galactic dynamics and gravitational lensing in galaxy clusters without
requiring dark matter. If this type of formula exists, we show that it is
possible that it can clearly indicate that dark matter is either perfectly
tailored to baryonic matter or, from a more radical point of view, even perhaps
useless. If the latter situation is true, then we must give greater visibility
to models such as modified inertia (MOND) or even modified gravity (MOG).
