Editing Copernican principle (section)

==Physics without the principle==
The standard model of cosmology, the [[Lambda-CDM model]], assumes the Copernican principle and the more general [[cosmological principle]]. Some cosmologists and theoretical physicists have created models without the cosmological or Copernican principles to constrain the values of observational results, to address specific known issues in the Lambda-CDM model, and to propose tests to distinguish between current models and other possible models.

A prominent example in this context is [[inhomogeneous cosmology]], to model the observed [[accelerating universe]] and [[cosmological constant]]. Instead of using the current accepted idea of [[dark energy]], inhomogeneous-cosmology models propose that the universe is much more inhomogeneous than currently assumed — for example, that we are in an extremely large low-density void.<ref name=void>{{Cite journal | last1 = February | first1 = S. | last2 = Larena | first2 = J. | last3 = Smith | first3 = M. | last4 = Clarkson | first4 = C. | title = Rendering dark energy void | doi = 10.1111/j.1365-2966.2010.16627.x | journal = Monthly Notices of the Royal Astronomical Society | volume = 405 | issue = 4 | page = 2231 | year = 2010 | doi-access = free |arxiv = 0909.1479 |bibcode = 2010MNRAS.405.2231F | s2cid = 118518082 }}</ref> To match observations we would have to be very close to the centre of this void, immediately contradicting the Copernican principle.

While the [[Big Bang]] model in cosmology is sometimes said to derive from the Copernican principle in conjunction with redshift observations, the Big Bang model can still be assumed to be valid in absence of the Copernican principle, because the [[cosmic microwave background]], primordial gas clouds, and the [[Structure formation|structure]], [[Galaxy formation and evolution|evolution]], and distribution of [[galaxies]] all provide evidence, independent of the Copernican principle, in favor of the Big Bang. However, the key tenets of the Big Bang model, such as the expansion of the universe, become assumptions themselves akin to the Copernican principle, rather than derived from the Copernican principle and observations.