# Tests and problems of the standard model in Cosmology

## TL;DR

This paper reviews the foundational assumptions, tests, and challenges of the standard $\\Lambda$CDM cosmological model, highlighting areas where observations align or conflict with its predictions and exploring alternative theories.

## Contribution

It provides a comprehensive review of the tests and problems of the standard cosmological model, including discussion of alternative models.

## Key findings

- Standard model fits many observations but has unresolved issues.
- Numerous tests support the model, yet some data challenge its assumptions.
- Alternative models are considered to address observed discrepancies.

## Abstract

The main foundations of the standard $\Lambda $CDM model of cosmology are that: 1) The redshifts of the galaxies are due to the expansion of the Universe plus peculiar motions; 2) The cosmic microwave background radiation and its anisotropies derive from the high energy primordial Universe when matter and radiation became decoupled; 3) The abundance pattern of the light elements is explained in terms of primordial nucleosynthesis; and 4) The formation and evolution of galaxies can be explained only in terms of gravitation within a inflation+dark matter+dark energy scenario. Numerous tests have been carried out on these ideas and, although the standard model works pretty well in fitting many observations, there are also many data that present apparent caveats to be understood with it. In this paper, I offer a review of these tests and problems, as well as some examples of alternative models.