  Assuming a closed universe with slight positive curvature, cosmic expansion
is modeled as a heat engine where the '"system'" is defined collectively as
those regions of space within the observable universe which will later evolve
into voids or empty space, and the '"surroundings'" are identified collectively
as those pockets of space which will eventually develop into matter filled
galaxies, clusters, super-clusters and filament walls. Using this model, we
show that the energy needed for cosmic expansion can be found using basic
thermodynamic principles, and that cosmic expansion had as its origin, a finite
initial energy density, pressure, volume, and temperature. Inflation in the
traditional sense, with the inflaton field, may also not be required as it can
be argued that homogeneities and in-homogeneities in the WMAP temperature
profile can be attributed to quantum mechanical fluctuations about a fixed
background temperature in the initial isothermal expansion phase. Fluctuations
in temperature can cause certain regions of space to lose heat to other pockets
producing voids forcing, i.e., fueling expansion of the latter and creating
slightly cooler temperatures in the former, where matter will later congregate.
Upon freeze-out, this could produce the observed WMAP signature with its
associated CBR fluctuation in magnitude. Finally, we estimate that the
freeze-out temperature and time for WMAP in-homogeneities occurred at roughly
3.02 * 1027 K and 2.54 * 10-35 s, respectively, after first initiation of
volume expansion, in line with current estimates for the end of the
inflationary epoch. The heat absorbed in the inflationary phase is estimated to
be Q = 1.81 * 1094 J, and the system volume increases by a factor of only 5.65.
The bubble voids in the observable universe increase, collectively, in volume
from about .046 m3 to .262 m3 within this time.
