154 Cosmological models
Given these problems, any progress is of necessity based on specific
philosophical positions, which decide which of the many possible physical and
metaphysical approaches is to be preferred. These philosophical positions should
be identified as such and made explicit [37, 88]. As explained earlier, no
experimental test can determine the nature of any mechanisms that may be in
operation in circumstances where even the concepts of cause and effect are
suspect. Initial conditions cannot be determined by the laws of physics alone—
for if they were so determined they would no longer be contingent conditions, the
essential feature of initial data, but rather would be necessary. A purely scientific
approach cannot succeed in explaining this specific nature of the universe.
Consequent on this situation, it follows that unavoidably, whatever approach
one may take to issues of cosmological origins, metaphysical issues inevitably
arise in cosmology: philosophical choices are needed in order to shape the theory.
That feature should be explicitly recognized, and then sensibly developed in the
optimal way by carefully examining the best way to make such choices.
3.10 Conclusion
There is a tension between theory and observation in cosmology. The issue we
have considered here is, Which family of models is consistent with observations?
To answer this demands an equal sophistication of geometry and physics, whereas
in the usual approaches there is a major imbalance: very sophisticated physics and
very simple geometry. We have looked here at tools to deal with the geometry
in a resaonably sophisticated way, and summarized some of the results that are
obtained by using them. This remains an interesting area of study, particularly in
terms of relating realistic inhomogeneous models to the smoothed out standard
FL models of cosmology.
Further problems arise in considering the physics of the extremely early
universe, and any pre-physics determining initial conditions for the universe.
We will need to develop approaches to these topics that explicitly recognizes
the limitations of the scientific method—assuming that this method implies the
possibility of verification of our theories.
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