# Final Scientific/Technical Report-Quantum Field Theories for Cosmology

## Abstract

The research funded by this award spanned a wide range of subjects in theoretical cosmology and in field theory. In the first part, the PI and his collaborators applied effective field theory techniques to the study of macroscopic media and of cosmological perturbations. Such an approach—now standard in particle physics—is quite unconventional for theoretical cosmology. They addressed several concrete questions where this formalism proved valuable, both within and outside the cosmological context, concerning for instance macroscopic physical phenomena for fluids, superfluids, and solids, and their relationship to the dynamics of cosmological perturbations. A particularly successful outcome of this line of research has been the development of “solid inflation”: a cosmological model for primordial inflation where the expansion of the universe is driven by an exotic solid substance. In the second part, the PI and his collaborators investigated more fundamental questions and ideas, for the present universe as well as for the very early one, using quantum field theory as a guide. The questions addressed include: Is the present cosmic acceleration due to a new, ‘dark’ form of energy, or are we instead observing a breakdown of Einstein’s general relativity at cosmological distances? Is the cosmic acceleration accelerating? Is the Bigmore »

- Authors:

- Columbia Univ., New York, NY (United States). Physics Dept.

- Publication Date:

- Research Org.:
- Columbia Univ., New York, NY (United States). Board of Trustees

- Sponsoring Org.:
- USDOE Office of Science (SC)

- OSTI Identifier:
- 1425341

- Report Number(s):
- DOE-COLUMBIA-06395

- DOE Contract Number:
- SC0006395

- Resource Type:
- Technical Report

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTRONOMY AND ASTROPHYSICS

### Citation Formats

```
Nicolis, Alberto.
```*Final Scientific/Technical Report-Quantum Field Theories for Cosmology*. United States: N. p., 2018.
Web. doi:10.2172/1425341.

```
Nicolis, Alberto.
```*Final Scientific/Technical Report-Quantum Field Theories for Cosmology*. United States. doi:10.2172/1425341.

```
Nicolis, Alberto. Sat .
"Final Scientific/Technical Report-Quantum Field Theories for Cosmology". United States.
doi:10.2172/1425341. https://www.osti.gov/servlets/purl/1425341.
```

```
@article{osti_1425341,
```

title = {Final Scientific/Technical Report-Quantum Field Theories for Cosmology},

author = {Nicolis, Alberto},

abstractNote = {The research funded by this award spanned a wide range of subjects in theoretical cosmology and in field theory. In the first part, the PI and his collaborators applied effective field theory techniques to the study of macroscopic media and of cosmological perturbations. Such an approach—now standard in particle physics—is quite unconventional for theoretical cosmology. They addressed several concrete questions where this formalism proved valuable, both within and outside the cosmological context, concerning for instance macroscopic physical phenomena for fluids, superfluids, and solids, and their relationship to the dynamics of cosmological perturbations. A particularly successful outcome of this line of research has been the development of “solid inflation”: a cosmological model for primordial inflation where the expansion of the universe is driven by an exotic solid substance. In the second part, the PI and his collaborators investigated more fundamental questions and ideas, for the present universe as well as for the very early one, using quantum field theory as a guide. The questions addressed include: Is the present cosmic acceleration due to a new, ‘dark’ form of energy, or are we instead observing a breakdown of Einstein’s general relativity at cosmological distances? Is the cosmic acceleration accelerating? Is the Big Bang unavoidable? Related to this, is early inflation the only sensible cure for the shortcomings of the standard Big Bang model, and the only possible source for the observed scale-invariant cosmological perturbations?},

doi = {10.2172/1425341},

journal = {},

number = ,

volume = ,

place = {United States},

year = {Sat Mar 10 00:00:00 EST 2018},

month = {Sat Mar 10 00:00:00 EST 2018}

}