# Quantum transitions through cosmological singularities

## Abstract

In a quantum theory of cosmology spacetime behaves classically only in limited patches of the configuration space on which the wave function of the universe is defined. Quantum transitions can connect classical evolution in different patches. Working in the saddle point approximation and in minisuperspace we compute quantum transitions connecting inflationary histories across a de Sitter like throat or a singularity. This supplies probabilities for how an inflating universe, when evolved backwards, transitions and branches into an ensemble of histories on the opposite side of a quantum bounce. Generalising our analysis to scalar potentials with negative regions we identify saddle points describing a quantum transition between a classically contracting, crunching ekpyrotic phase and an inflationary universe.

- Authors:

- Max Planck Institute for Gravitational Physics (Albert Einstein Institute), 14476 Potsdam-Golm (Germany)
- Institute for Theoretical Physics, KU Leuven, 3001 Leuven (Belgium)

- Publication Date:

- OSTI Identifier:
- 22676121

- Resource Type:
- Journal Article

- Journal Name:
- Journal of Cosmology and Astroparticle Physics

- Additional Journal Information:
- Journal Volume: 2017; Journal Issue: 07; 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; APPROXIMATIONS; CONFIGURATION; COSMOLOGY; DE SITTER SPACE; INFLATIONARY UNIVERSE; PHARYNX; SINGULARITY; SPACE-TIME; UNIVERSE; WAVE FUNCTIONS

### Citation Formats

```
Bramberger, Sebastian F., Lehners, Jean-Luc, Hertog, Thomas, and Vreys, Yannick, E-mail: sebastian.bramberger@aei.mpg.de, E-mail: thomas.hertog@kuleuven.be, E-mail: jlehners@aei.mpg.de, E-mail: yannick.vreys@kuleuven.be.
```*Quantum transitions through cosmological singularities*. United States: N. p., 2017.
Web. doi:10.1088/1475-7516/2017/07/007.

```
Bramberger, Sebastian F., Lehners, Jean-Luc, Hertog, Thomas, & Vreys, Yannick, E-mail: sebastian.bramberger@aei.mpg.de, E-mail: thomas.hertog@kuleuven.be, E-mail: jlehners@aei.mpg.de, E-mail: yannick.vreys@kuleuven.be.
```*Quantum transitions through cosmological singularities*. United States. doi:10.1088/1475-7516/2017/07/007.

```
Bramberger, Sebastian F., Lehners, Jean-Luc, Hertog, Thomas, and Vreys, Yannick, E-mail: sebastian.bramberger@aei.mpg.de, E-mail: thomas.hertog@kuleuven.be, E-mail: jlehners@aei.mpg.de, E-mail: yannick.vreys@kuleuven.be. Sat .
"Quantum transitions through cosmological singularities". United States. doi:10.1088/1475-7516/2017/07/007.
```

```
@article{osti_22676121,
```

title = {Quantum transitions through cosmological singularities},

author = {Bramberger, Sebastian F. and Lehners, Jean-Luc and Hertog, Thomas and Vreys, Yannick, E-mail: sebastian.bramberger@aei.mpg.de, E-mail: thomas.hertog@kuleuven.be, E-mail: jlehners@aei.mpg.de, E-mail: yannick.vreys@kuleuven.be},

abstractNote = {In a quantum theory of cosmology spacetime behaves classically only in limited patches of the configuration space on which the wave function of the universe is defined. Quantum transitions can connect classical evolution in different patches. Working in the saddle point approximation and in minisuperspace we compute quantum transitions connecting inflationary histories across a de Sitter like throat or a singularity. This supplies probabilities for how an inflating universe, when evolved backwards, transitions and branches into an ensemble of histories on the opposite side of a quantum bounce. Generalising our analysis to scalar potentials with negative regions we identify saddle points describing a quantum transition between a classically contracting, crunching ekpyrotic phase and an inflationary universe.},

doi = {10.1088/1475-7516/2017/07/007},

journal = {Journal of Cosmology and Astroparticle Physics},

issn = {1475-7516},

number = 07,

volume = 2017,

place = {United States},

year = {2017},

month = {7}

}