A non-standard cosmology is a cosmological theory that contradicts the standard model of cosmology. The term has been used since the late 1960s after the discovery of the cosmic background radiation (CBR) in 1965 by Penzias and Wilson. These observations combined with observations of big bang nucleosynthesis and other evidence suggesting that the universe was evolving caused most cosmologists to favor the Big Bang theory over the steady state theory.

While non-standard models, including the steady-state theory, often have explanations for phenomenon for observations such as cosmic microwave background, which is seen as residual radiation from old stars, most cosmologists as of 2004, believe that the big bang theory provides a more coherent view of the universe that more closely fits observations.

Since around the time of the observation of the CBR, in practice a non-standard cosmology has primarily meant any cosmological theory which argues that the Big Bang theory is fundamentally incorrect. While there are a number of observations which are not currently explained well by big bang cosmologies, the prevailing opinion among cosmologists is that these observations can be incorporated within a big bang cosmology without major changes to the foundations of the theory. However, non-standard cosmologies assert that this procedure will fail and to coherently address these issues from a framework which is not in contradiction to empirical observation and experiment will require a basic reevaluation of the standard model.

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http://en.wikipedia.org/wiki/Non-standard_cosmology