The creation of the Universe. Illustration depicting the history of the formation of the Universe, based on the theory of the inflationary Big Bang and data from NASA's COBE satellite. The Big Bang is at top left. After a minute fraction of a second, small fluctuations in the energy 'soup' of the Universe have appeared. A period of rapid 'inflationary' expansion followed. 300,000 years later, these fluctuations had formed the ripples" in the microwave background detected by COBE in 1991-2 (centre). These patterns of energy show that vast amounts of 'dark' matter existed, which provided gravity to form the galaxies seen today, 15 billion years later (bottom right)."