Dynamics in A Maximally Symmetric Universe
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Date
2012-03
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Addis Ababa University
Abstract
Our present understanding of the evolution of the universe relies upon the Friedmann-
Robertson- Walker cosmological models. This model is so successful that it is now being
considered as the Standard Model of Cosmology. So in this work we derive the Friedmann
equations using the Friedmann-Robertson-Walker metric together with Einstein
eld equation and then we give a simple method to reduce Friedmann equations to a
second order linear di erential equation when it is supplemented with a time dependent
equation of state. Furthermore, as illustrative examples, we solve this equation for some
speci c time dependent equation of states. And also by using the Friedmann equations
with some time dependent equation of state we try to determine the cosmic scale factor(the
rate at which the universe expands) and age of the Friedmann universe, for the matter
dominated era, radiation dominated era and for both matter and radiation dominated era
by considering di erent cases. We have nally discussed the observable quantities that
can be evidences for the accelerated expansion of the Friedmann universe
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Dynamics in A Maximally Symmetric