EXPANSION SPEEDS AND ACCELERATIONS OF THE UNIVERSE IN FIVE GENERAL COSMIC MODELS

Four new cosmological quantities were introduced which are the horizon expansion speed, horizon expansion acceleration, horizon volume speed and horizon volume acceleration of the universe expansion. These quantities have been investigated in five general cosmic models. The distributions of the space expansion speed of the universe in these models decrease up to minimum values, then they increase slowly until. Gyr, and hence rise appreciably faster. In the observed general model the minimum space expansion speed is at . Gyr. However, the distributions of the horizon expansion speed of the universe in the general models continuously descend with cosmic time. At the present time in the observed general model . On the other hand, the distributions of the horizon volume speed of the universe expansion surge slowly until .yr, afterwards they ascend more rapidly up to maximum values, and hence they decrease gradually towards zero. At the present time in the observed general model . while the maximum horizon volume speed is at 3. Gyr. The distributions of the speed expansion acceleration of the universe in the general models exhibit steep rise towards 1. and remain very close to this value, then they increase very slowly up to 2. Gyr, then they rise more rapidly, however after . Gyr they surge substantially faster. Nevertheless, the distributions of the horizon expansion acceleration of the universe in the general models display sharp ascension towards . and stay so adjacent to this value hence after . Gyr. Finally, the distributions of the horizon volume acceleration of the universe expansion in the general models decline with time unit . Gyr where they remain close to . At the present time in the observed general model .

It is found that the four new cosmological quantities are strongly related to the distribution of the total pressure of the universe.