  This paper collects a consistent body of information on the observable
Universe, from which an estimate of the total mass of the Universe is
calculated as a function of the angle whose vertex is at the center of the
Universe, and whose extremities stand on the Earth and on the limits of the
horizon of visibility. This result leads to an analysis of the dynamics of the
Big-Bang, taking into account the limitations imposed by the Schwarzschild
radius, $R_S$. Where if $R_0$ is the radius of the incipient Universe when the
formation of elementary particles has just finished, the value of the quotient
$R_0/R_S$ determines its subsequent evolution. An important conclusion from
this concerns the expansion of the Universe; all signs point to its being
destined to expand indefinitely.
