  The astrophysicist S. Mc Gaugh recently published (3) a result raising
questions concerning the existence of dark matter and the validity of General
Relativity, conclusion of his observations of 47 galaxies. He established the
validity of Tully-Fisher's law for all those galaxies, which is unexplained and
in contradiction with classical Cosmology based on General Relativity.
Moreover, we remind that this classical Cosmology did not solve the enigma of
the nature of dark matter, nor the enigma of its invisibility, nor the enigma
of the constancy of the curve of velocities of stars in a galaxy. Consequently
it appears that a new Cosmology, alternative to the classical Cosmology, is
necessary, at least in the field of dark matter. In fact it exists already a
new Cosmology, alternative to classical Cosmology and compatible with the
Relativity Theory, which is the Cosmology of the Theory of Ether relative to
dark matter. This new Cosmology gives the nature of dark matter, the origin of
its invisibility and permits to obtain the constancy of the curve of velocities
of stars in a galaxy. In this article, after having recalled the theoretical
elements of this new Cosmology, we will show that it also permits to obtain
theoretically Tully-Fisher's law whose Mc Gaugh observations confirmed the
validity. We will note that all the theoretical results used and obtained in
this article are compatible with the Special and General Relativity Principles.
