Inflationary cosmology and the scale-invariant spectrum

The first section of the paper explains what a scale-invariant power-spectrum is, and the requirements placed on a cosmological theory of such density perturbations. The second section explains and analyses the concept of the Hubble horizon, and its behaviour within an inflationary space-time. The third section expounds the inflationary derivation of scale-invariance, and scrutinises the assumptions within that derivation. The fourth section analyses the explanatory role of 'horizon-crossing' within the inflationary scenario.