Missing Mass, Dark Energy and the Acceleration of the Universe. Is Acceleration Here to Stay?

Abstract

In this paper we present an alternative explanation to the acceleration of the universe and the dark energy problems in terms of the Friedmann Thermodynamics. This model has the capability of making definite predictions in-line with the current observations of the universe. According to this model, cosmos was expanding slower at the beginning. During the galaxy formation era (with redshifts [0.54-0.91]), due to a change in the global equation of state it accelerates for a brief period of time. We expect to see this as a discontinuity in the Hubble diagram. Recent data about the galaxies with redshifts 0.5 1 is gathered. These galaxies will be among the very first galaxies formed in the universe, thus still showing the kinematics of the pre-galaxy formation era. This point is now clearly evidenced in the recent data by Riess et al. on Type Ia supernovae with redshifts z>1.25 (2004 astro-ph/0402512). In our model, galaxies with redshifts 0<z<0.5 should reflect the kinematics of the universe after the transition is completed. These galaxies are now receding from each other faster. However, for redshifts towards the upper end of this range we still expect to see deceleration. This is in contrast with the predictions of the dark energy models.