The original application
of general relativity to the universe showed that the universe is expanding, albeit at a
decreasing rate. Supernova data have established that although early in its
history the universe was expanding at a decreasing rate, the rate of expansion
has been increasing for the past several billion years. Einstein’s equations
were modified by adding the cosmological constant to make the expansion of the universe
accelerate and
fit the data, giving birth to the notion of dark energy. However, there is to
date no good explanation of dark energy. This paper proposes that Einstein’s
original equations be left alone and that instead, the model assumed for the
expanding universe be changed: from a single uniformly isotropic expanding
space universe of constant mass to a similarly expanding universe surrounded by
an isotropic, uniform shell. The overall mass of the structure remains constant.
This new geometry produces the observed expansion behavior of the universe and
is simply a result of different initial conditions.

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