  In this work, we compute the universe temperature for the cosmological
horizon for the FLRW metric. For this purpose, we consider a scalar field on
the cosmological horizon. This scalar field satisfies the Klein-Gordon equation
in a curved space-time. Recently, some authors like Barrow, Bekenstein and
others have proposed that the fundamental constants might vary with time. Along
these lines of thought, we derive the electromagnetic momentum and
electromagnetic field for the FLRW universe. This enables us to obtain a
temporal dependence of the Hubble parameter which, in turn, induces a time
dependence of the fundamental constants. In order to validate this model, the
theoretical predictions are then compared with observational data as a function
of the redshift, $z$, for the universe expansion. As a consequence, this time
dependence on the fundamental constants makes it possible to predict a change
in time of the informational content for the entropy of the universe surface
area, this is expressed as the bit number by using the holographic principle.
