PHYSICAL ASTROCHEMISTRY IN THE EVOLUTION OF THE DARK UNIVERSE

        We present a thermodynamic  approach in  modeling the evolution of the universe based on a  theory that space  consists of energy quanta, the spaceons. From wave-particle duality, they can be treated as an ideal gas.The model provides an insight on the  nature of dark energy and dark matter, as well as a rationale for  the accelerated expansion of the universe.

          The universe started from an atomic size volume of spaceons at very high  temperature and pressure. Upon expansion  and  cooling, phase transitions occurred  resulting in the formation of fundamental particles, and matter. These  nucleate and grow into stars, galaxies, and clusters due to the action of gravity. From the cooling curve of the universe we constructed a thermodynamic phase diagram of cosmic  composition, from which we  obtained  the correlation between   dark energy  and the energy of space. Using Friedmann’s equations,  our model fits well the WMAP data on cosmic composition  with an equation of state parameter, w= -0.7.  The dominance  of dark energy started at 7.25 x 10⁹ years,   in good agreement  with BOSS measurements. The  expansion of space is attributed to  a scalar quantum space field.  Dark Matter is identified as  a plasma form of matter similar to that which existed during the photon epoch, prior to recombination.

         The thermodynamics of expansion of the universe   was   adiabatic and decelerating  during  the first  7  billion years after the Big Bang; it accelerated thereafter.  In a closed universe,  a  negative pressure of Dark Energy is required to sustain the latter. This is consistent with the theory of General Relativity and the law of conservation of energy.  We propose a mechanism for the acceleration as due to consolidation of matter on the way to forming Planck Stars ; the resulting  reduction in gravitational potential energy feeds back  energy for the expansion.  The universe will likely wind up in a  “deep freeze”.  The possibility of  a “big bounce” leading to a “resurrected” and   cyclic universe is discussed. The ultimate destiny  in both cases is an eternal universe.