  At this beginning of the 21st century, the situation of physics is not
without analogy with that which prevailed a hundred years ago, with the outset
of the double scientific revolution of relativity and quanta. On the one hand,
recent progress of observational cosmology makes think that one has discovered
a new universal constant, perhaps as fundamental as the velocity of light or
the Planck's constant, the cosmological constant, which could explain the
acceleration of the expansion of the universe. On the other hand, just like the
efforts of Planck and Einstein to reconcile thermodynamics and the
electromagnetic theory of light led to the operational beginning of quantum
physics, the unexpected discovery of bonds between thermodynamics and general
relativity makes to foresee new concepts, perhaps heralding a new scientific
revolution, like that of holography and leads to consider a "thermodynamic
route towards quantum cosmology." We will discuss the possible implications of
these observational and theoretical developments.
