To be published in New Astronomy, (2001?) (astro-ph/0009491)

Abstract. A short introduction to structure formation is given, followed by a discussion of the possible characteristics of the initial perturbations assuming a generic inflationary origin. Observational data related to large-scale structure and the cosmic microwave background radiation is then used in an attempt to constrain the characteristics of such perturbations. Future directions are also explored.

The possibility of direct detection of a stochastic gravitational wave background produced during an inflationary phase in the early Universe is briefly discussed, as well as the available evidence regarding the present value of the total energy density in the Universe.

Key words: Cosmology; Inflation

Table of Contents

OVERVIEW

STRUCTURE FORMATION AND INFLATION

Introduction

Adiabatic vs. entropy perturbations

Passive vs. active perturbations

Gaussian vs. non-Gaussian perturbations

Scale-invariant perturbations ?

THE CMBR AND INFLATION

DIRECT DETECTION OF GRAVITATIONAL WAVES

IS THE UNIVERSE FLAT ?

REFERENCES