**Introduction**

**Chapter 1**

**Provisional chapter**

**Introductory Chapter: The Physics of Dark Sector**

**Introductory Chapter: The Physics of Dark Sector**

DOI: 10.5772/intechopen.80234

In the last two decades, researches in cosmology and astrophysics provided an important source of data about the gravitational and evolutionary structure of the universe, which stimulates a demand for gravitational theories beyond general relativity in the face of the new conjuncture of the problems of contemporary physics. The physics of dark sector has been one of the most intriguing problems of physics. Since the rise of dark matter problem in the very beginning of the twentieth century and the appearance of the dark energy in the end of 1990s, they launched a new scenario for contemporary physics and some examples of questions can be made such as: Have those problems a true substance of reality? Is there an underlying new physics that describes such issues? Is it possible to explain those problems without changing the ordinary physical theories? Do we need another particle theory? And

Since the works of Einstein, our sense of gravity had been radically changed since it can be interpreted as a geometrical effect. Einstein's new approach indicated that geometry plays a fundamental role in a physical process. More interestingly, one can state a more profound meaning on gravity as: gravity does not need matter to exist. In Einstein's sense, gravity is also self-interactive, that is, Einstein's field equations exist on vacuum that evinces the grandeur of a geometric approach on a physical theory. In other words, general relativity is the only physical theory that allows a nontrivial vacuum solution. It must be said that it is rather different from Newton's theory of gravitation that a vectoral field of force does exist to provide interaction between two separated masses. Nonetheless, the problem of searching physics for dark sector essentially involves finding eventually new prospects on the meaning of gravity, once dark matter problem and the dark energy are at the first instance effects of gravity.

This book is devoted to discussing fundamental aspects of the dark matter problem. The modern roots on the dark matter problem were basically launched in the 1930s, with Zwicky's

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© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. Distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (https://creativecommons.org/licenses/by-nc/4.0/), which permits use, distribution

Abraão Jessé Capistrano de Souza

Abraão Jessé Capistrano de Souza

http://dx.doi.org/10.5772/intechopen.80234

**1. On the physics of dark sector**

the central point, what is gravity?

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter
