Published in 1992, "Observational and Physical Cosmology".

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Abstract. Big Bang nucleosynthesis (BBNS) theory is sketched, indicating the dependence of primordial abundances of D, ³He, ⁴He and ⁷Li on the mean baryonic density of the universe and the dependence of ⁴He on the number of neutrino families and the neutron half-life. Observational data and inferred primordial abundances of these elements are reviewed and shown to be consistent (within errors) either with standard BBNS in a homogeneous universe about 100 seconds after the Big Bang or with moderately inhomogeneous BBNS models resulting from earlier phase transitions like the quark-hadron transition if this is first order. However, models with closure density supplied by baryons are apparently ruled out. Finally, implications for the existence of baryonic and non-baryonic dark matter are briefly discussed.

Table of Contents

INTRODUCTION

The hot Big Bang

Primordial Nucleosynthesis

Non-standard BBNS models

Primordial abundances

DEUTERIUM AND³He

Deuterium

Helium 3

Primordial D+ ³He

LITHIUM 7

Lithium in the galaxy

Lithium in subdwarfs

HELIUM 4

Introduction

Recombination lines in nebulae

Complications in emission-line analysis

Newer results

The primordial helium abundance

REFERENCES