This is a picture is the most accurate and detailed map of the oldest light in the Universe. The radiation originally formed about 380,000 years after the Big Bang, when all matter was created some 13.82 billion years ago.
Scientists call this radiation 'the cosmic microwave background' because it pervades all corners of space – providing a universal backdrop – due to the fact that it was formed so soon after the event that led to an ever-expanding Universe.
The image is the culmination of nearly 16 months of work on data gathered by the European Space Agency’s Planck space telescope, a satellite launched in 2009 that has been collecting the very slight temperature fluctuations in what has become known as the relic radiation of the Big Bang.
Scientists said the data indicates that the Universe is expanding at a slightly slower rate than previously believed, making it about somewhat older than the 13.7 billion years formerly given for the age of the Universe.
Differences in the colours of the map represent tiny variations in the temperature of the microwave background radiation, an extremely cold remnant of the Big Bang set at about 2.7 degrees above absolute zero (-273C).
These temperature variations correspond to regions of slightly different densities in the very earliest stages of the Universe when everything was a smooth soup of subatomic particles. These ripples represent the initial clumping together of matter to form the “seeds” of future stars and galaxies.
“This is the best ever baby picture of the Universe. It represents the moment when it was very young,” said Mark Ashdown, a Planck scientist at the University of Cambridge.
At this early point in time, the Universe was filled with a hot, dense soup of protons, electrons and photons that were interacting at temperatures of about 2,700C. When the protons and electrons joined together to form hydrogen atoms, light was set free.
This light became stretched out to microwave wavelengths as the Universe went through a rapid phase of expansion. The fluctuations in temperature and density of this microwave radiation reflect what happened within the first fractions of second after the Big Bang.
“The sizes of these tiny ripples hold the key to what happened in that first trillionth of a trillionth of a second. Planck has given us striking new evidence that indicates they were created during the incredibly fast expansion just after the Big Bang,” said Joanna Dunkley of Oxford University.
Scientists have peeled away the layers of light and radiation that separates us from this relic of the Big Bang, revealing a picture of an early universe that conforms remarkably well to the standard model of cosmology.
“Since the release of Planck’s first all-sky map image in 2010, we have been carefully extracting and analysing all the foreground emissions that lie between us and the Universe’s first light, revealing the cosmic background in the greatest detail yet,” said George Efstanthiou of Cambridge University.
Although the measurements made by Planck match the theoretical predictions of what the Universe should look like, there are some important differences, such as a notable asymmetry between the opposite hemispheres of the sky and a “cold spot” that extends over a much larger patch of the sky than expected.
“The fact that Planck has made such a significant detection of these anomalies erases any doubts about their reality; it can no longer be said that they are artefacts of the measurements. They are real and we have to look for a credible explanation,” said Paolo Natoli of Ferrara University in Italy.
Jan Tauber, Planck’s project scientist based in the Netherland, added: “On the one hand we have a simple model that fits our observations extremely well, but on the other hand we see some strange features which force us to rethink some of our basic assumptions.”