The European Space Agency’s Planck satellite has released the most detailed map of the universe ever created, refining estimates of the age of the universe and its composition, as well as showing some interesting anomalies that scientists can’t yet explain.
Launched in 2009, Planck has been gathering data on the cosmic background radiation, an extremely cold glow leftover from the Big Bang. This radiation corresponds to particles of light that were emitted just 380,000 years after the universe was born, when the first atoms were formed. At that time, the entire cosmos was filled with white-hot radiation of 2,700 degrees Celsius. Over the age of the universe, the radiation has cooled to just 2.7 degrees above absolute zero. It now comes almost uniformly from every area of the sky at once.
“Planck’s data delivers a remarkable abundance of riches,” said cosmologist Krzysztof Gorski, who works on the U.S. portion of the Planck mission, during a NASA press conference Thursday. “We are very excited about the results as Planck gives us a chance to peek into the unknown.”
Scientists can look at the light from this era to determine the basic characteristics of the universe. Planck’s data tells cosmologists that the universe is 13.8 billion years old, about 100 million years older than previously thought, and contains slightly more matter, both ordinary and dark, than previous data suggested. It was also apparently expanding slightly faster at earlier times and slightly slower at later times than previously thought.
“The detailed measurements of the basic properties of the universe are slightly changed, but the overall picture is evolutionary, not revolutionary,” wrote physicist Matt Strassler of Rutgers University in New Jersey on his blog, Of Particular Significance, adding that it will still take a while to sift through the data and uncover all its significant components.
The cosmic background radiation is extremely uniform, giving credence to a theory known as inflation, which posits that a tiny fraction of second after the Big Bang the universe suddenly expanded in size nearly 100 trillion times. But there are subtle variations, typically a 100 millionth of a degree, that correspond to quantum ripples in the very early universe just a trillionth of a trillionth of a second after the universe was born.
“The contrast is turned way up in this image,” said cosmologist Charles Lawrence, project scientist of the U.S. Planck mission, during the NASA press conference.
The variations are important because they represent small clumps where slightly more matter existed in the early universe. These subatomic clumps acted like little Katamari balls, drawing other matter from around them and becoming the seeds from which larger entities, such as stars and galaxies, grew.
Though they are uniform in general, there are unexplained anomalies in the ripples. The finding is a strange variation between two halves of the universe: The photons in one half of the sky are slightly hotter than in the other half. There is also a large and unexplained cold spot. This was a result seen in Planck’s cosmic-microwave-background-mapping precursor, the WMAP spacecraft, but Planck has now confirmed that it is real and not just a statistical fluke.
“A clear cut interpretation is lacking,” said Gorski, but it could require new ideas of how physics or the universe work.
In other ways, though, the new Planck data quashes hopes for bizarre new physics. The findings provide zero evidence for cosmic strings, which might be expected under string theory, and can say almost nothing about the multiverse — that is, universes beyond our own — because inflation would hide evidence of their existence. The findings also show no indication of a hypothetical fourth class of neutrino, which would act slightly differently than the three neutrinos we know about and could help explain certain anomalous findings in experiments on Earth.