# Cosmology in time asymmetric extensions of general relativity

## Abstract

We investigate the cosmological behavior in a universe governed by time asymmetric extensions of general relativity, which is a novel modified gravity based on the addition of new, time-asymmetric, terms on the Hamiltonian framework, in a way that the algebra of constraints and local physics remain unchanged. Nevertheless, at cosmological scales these new terms can have significant effects that can alter the universe evolution, both at early and late times, and the freedom in the choice of the involved modification function makes the scenario able to produce a huge class of cosmological behaviors. For basic ansatzes of modification, we perform a detailed dynamical analysis, extracting the stable late-time solutions. Amongst others, we find that the universe can result in dark-energy dominated, accelerating solutions, even in the absence of an explicit cosmological constant, in which the dark energy can be quintessence-like, phantom-like, or behave as an effective cosmological constant. Moreover, it can result to matter-domination, or to a Big Rip, or experience the sequence from matter to dark energy domination. Additionally, in the case of closed curvature, the universe may experience a cosmological bounce or turnaround, or even cyclic behavior. Finally, these scenarios can easily satisfy the observational and phenomenological requirements.more »

- Authors:

- Instituto de Física, Pontificia Universidad de Católica de Valparaíso, Casilla 4950, Valparaíso (Chile)
- Physics Division, National Technical University of Athens, Zografou Campus 15780, Athens (Greece)

- Publication Date:

- OSTI Identifier:
- 22525206

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2015; Journal Issue: 11; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ALGEBRA; ASYMMETRY; COSMOLOGICAL CONSTANT; COSMOLOGY; EVOLUTION; GENERAL RELATIVITY THEORY; GRAVITATION; HAMILTONIANS; MATHEMATICAL SOLUTIONS; NONLUMINOUS MATTER; UNIVERSE

### Citation Formats

```
Leon, Genly, and Saridakis, Emmanuel N., E-mail: genly.leon@ucv.cl, E-mail: Emmanuel_Saridakis@baylor.edu.
```*Cosmology in time asymmetric extensions of general relativity*. United States: N. p., 2015.
Web. doi:10.1088/1475-7516/2015/11/009.

```
Leon, Genly, & Saridakis, Emmanuel N., E-mail: genly.leon@ucv.cl, E-mail: Emmanuel_Saridakis@baylor.edu.
```*Cosmology in time asymmetric extensions of general relativity*. United States. doi:10.1088/1475-7516/2015/11/009.

```
Leon, Genly, and Saridakis, Emmanuel N., E-mail: genly.leon@ucv.cl, E-mail: Emmanuel_Saridakis@baylor.edu. Sun .
"Cosmology in time asymmetric extensions of general relativity". United States. doi:10.1088/1475-7516/2015/11/009.
```

```
@article{osti_22525206,
```

title = {Cosmology in time asymmetric extensions of general relativity},

author = {Leon, Genly and Saridakis, Emmanuel N., E-mail: genly.leon@ucv.cl, E-mail: Emmanuel_Saridakis@baylor.edu},

abstractNote = {We investigate the cosmological behavior in a universe governed by time asymmetric extensions of general relativity, which is a novel modified gravity based on the addition of new, time-asymmetric, terms on the Hamiltonian framework, in a way that the algebra of constraints and local physics remain unchanged. Nevertheless, at cosmological scales these new terms can have significant effects that can alter the universe evolution, both at early and late times, and the freedom in the choice of the involved modification function makes the scenario able to produce a huge class of cosmological behaviors. For basic ansatzes of modification, we perform a detailed dynamical analysis, extracting the stable late-time solutions. Amongst others, we find that the universe can result in dark-energy dominated, accelerating solutions, even in the absence of an explicit cosmological constant, in which the dark energy can be quintessence-like, phantom-like, or behave as an effective cosmological constant. Moreover, it can result to matter-domination, or to a Big Rip, or experience the sequence from matter to dark energy domination. Additionally, in the case of closed curvature, the universe may experience a cosmological bounce or turnaround, or even cyclic behavior. Finally, these scenarios can easily satisfy the observational and phenomenological requirements. Hence, time asymmetric cosmology can be a good candidate for the description of the universe.},

doi = {10.1088/1475-7516/2015/11/009},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 11,

volume = 2015,

place = {United States},

year = {2015},

month = {11}

}