A timely piece from ESA and Herschel because in the past few weeks I’ve been reviewing this time period. We cannot look back much further, if any, to the 380,000 year point (after the big bang) that I know of because before that the temperatures generated were too high; the universe was a dense mix of ions and free electrons. There were so many free electrons the photons were scattered and the universe was opaque.
Once the temperature dropped below 3,000 K, atoms formed and the number of free electrons dropped to the point where photons could escape and bingo, the Universe became transparent.
Those photons became a 3000 K blackbody. As time went on and the universe expanded (and it still is) those blackbody photons redshifted, redder wavelengths means cooler temperatures until we see it now as 2.7 K.
The idea of polarization, I’m still getting a handle on especially the “B-mode”. I’m currently reading one of Stephen Hawking’s books with a short section on polarization – this release helped clear up a few things.
From ESA and Herschel:
Using a telescope in Antarctica and ESA’s Herschel space observatory, astronomers 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.
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.