Astronomers using a telescope in Antarctica and ESA’s Herschel space observatory, have made the first detection of a subtle twist in the relic radiation from the Big Bang, paving the way towards revealing the first moments of the Universe’s existence. Image © ESA
The elusive signal was found in the way the first light in the Universe has been deflected during its journey to Earth by intervening galaxy clusters and dark matter, an invisible substance that is detected only indirectly through its gravitational influence.
The discovery points the way towards finding evidence for gravitational waves born during the Universe’s rapid ‘inflation’ phase, a crucial result keenly anticipated from ESA’s Planck mission.
The relic radiation from the Big Bang – the Cosmic Microwave Background, or CMB – was imprinted on the sky when the Universe was just 380 000 years old. Today, some 13.8 billion years later, we see it as a sky filled with radio waves at a temperature of just 2.7 degrees above absolute zero.
Tiny variations in this temperature – around a few tens of millionths of a degree – reveal density fluctuations in the early Universe corresponding to the seeds of galaxies and stars we see today. The most detailed all-sky map of temperature variations in the background was revealed by Planck in March.
But the CMB also contains a wealth of other information. A small fraction of the light is polarised, like the light we can see using polarised glasses. This polarised light has two distinct patterns: E-modes and B-modes.
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