# On the Magnetic Evolution in Friedmann Universes and the Question of Cosmic Magnetogenesis

## Abstract

**:**

## 1. Introduction

## 2. The Question of Cosmic Magnetogenesis

#### 2.1. The Scale Question

#### 2.2. The Strength Question

## 3. Magnetic Fields in Flat FRW Universes

#### 3.1. Causality and Large-Scale Magnetic Evolution

#### 3.2. Large-Scale Superadiabatic Magnetic Amplification

#### 3.3. The Epochs of Reheating, Radiation and Dust

#### 3.4. The Role of the Initial Conditions

## 4. The Residual Magnetic Field

#### 4.1. The Time of Second Horizon Crossing

#### 4.2. The Final Magnetic Strength

## 5. Implications for Cosmic Magnetogenesis

#### 5.1. Conventional Scenarios

#### 5.2. Non-Conventional Scenarios

## 6. The Case of Nearly Flat FRW Universes

#### 6.1. Marginally Open FRW Models

#### 6.2. Marginally Closed FRW Models

## 7. Discussion

## Conflicts of Interest

## References and Notes

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Tsagas, C.G.
On the Magnetic Evolution in Friedmann Universes and the Question of Cosmic Magnetogenesis. *Symmetry* **2016**, *8*, 122.
https://doi.org/10.3390/sym8110122

**AMA Style**

Tsagas CG.
On the Magnetic Evolution in Friedmann Universes and the Question of Cosmic Magnetogenesis. *Symmetry*. 2016; 8(11):122.
https://doi.org/10.3390/sym8110122

**Chicago/Turabian Style**

Tsagas, Christos G.
2016. "On the Magnetic Evolution in Friedmann Universes and the Question of Cosmic Magnetogenesis" *Symmetry* 8, no. 11: 122.
https://doi.org/10.3390/sym8110122