Theories without the use of cosmological principle.

In summary, there are some cosmological models that do not incorporate the cosmological principle, such as the Lemaitre-Tolman-Bondi dust and Oppenheimer-Snyder collapsing ball. However, the empirical evidence for the cosmological principle is strong, with phenomena like the large scale distribution of matter and the CMB supporting it. Some models assume equivalence to the standard cosmological model at observable scales, and there are currently cosmological models that include inhomogeneity and anisotropy at very large scales. This is due to the finite size of our inflationary bubble, which means the cosmological principle is not expected to apply at arbitrary large scales even within the standard model.
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are there theories in cosmology which do not incorporate/use the cosmological principle?
 
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There are some inhomogeneous and anisotropic cosmological models that were analyzed and studied in past, like the Lemaitre-Tolman-Bondi dust, the Oppenheimer-Snyder collapsing ball, etc. But in the meanwhile the empirical support of the cosmological principle is strong and there are lots of phenomena that are considered proofs of it, e.g. large scale distribution of matter (galaxies, quasars), CMB, X-ray background, peculiar velocities, etc. IMO the only way to take some of these models seriously is to assume that they are equivalent to the standard cosmological model at observable scales, for example like this one. This would shift a little bit your question to whether there are currently cosmological models in which there is assumed inhomogeneity or anisotropy at very large scales. The answer to this is yes, even within the standard cosmological model the cosmological principle is not expected to apply at arbitrary large scales because of the finite size of our inflationary bubble.
 

1. What is a theory without the use of cosmological principle?

A theory without the use of cosmological principle is a scientific model or explanation that does not rely on the assumption that the universe is homogenous and isotropic on a large scale. This means that the theory does not require the universe to look the same in all directions or at all points in time.

2. How do theories without the use of cosmological principle differ from other scientific theories?

Theories without the use of cosmological principle differ from other scientific theories in that they do not rely on the assumption of a homogenous and isotropic universe. Instead, they propose alternative explanations for the observed phenomena without relying on this principle.

3. What evidence supports theories without the use of cosmological principle?

There is a range of evidence that supports theories without the use of cosmological principle, including observations of the large-scale structure of the universe, the cosmic microwave background radiation, and the distribution of galaxies. These observations suggest that the universe is not homogenous and isotropic, and thus, support the need for alternative theories.

4. Are there any notable theories without the use of cosmological principle?

Yes, there are several notable theories without the use of cosmological principle, including the Steady State theory, the Quasi-Steady State Cosmology, and the Conformal Cyclic Cosmology. These theories propose alternative explanations for the observed expansion of the universe and the large-scale structure without relying on the assumption of a homogenous and isotropic universe.

5. How do theories without the use of cosmological principle impact our understanding of the universe?

Theories without the use of cosmological principle challenge our current understanding of the universe and offer alternative explanations for observed phenomena. They also highlight the importance of questioning and testing our assumptions in scientific theories to further our understanding of the cosmos.

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