David Weinberg: “Galaxies and large-scale structure form as a result of the gravitational amplification of tiny primordial fluctuations in the density of matter. The inflation hypothesis ascribes the origin of these fluctuations to quantum processes during a period of exponential expansion that occupied the first millionth-of-a-billionth-of-a-trillionth of a second of cosmic history. Experiments over the last decade have revealed the imprint of these fluctuations as part-in-100,000 intensity modulations of the cosmic microwave background (CMB), which records the small inhomogeneities present in the Universe half a million years after the big bang.” (Science Week)