22 March 2013

Planck reveals an almost perfect Universe

Discovery Center is part of the eagerly awaited release of Planck data and results. Results that in a heartbeat made the Universe 80 million years older, changed the content of the Universe and revealed the existence of features that challenge the foundations of our current understanding of the Universe.

On Thursday the 21st of march, the Planck science team released data and remarkable results from ESA’s Planck satellite. The Discovery Center Planck team were present both at the official press conference in Paris, and at an event in Planetarium in Copenhagen - giving a talk about the results from Planck.

Cosmic Microwave BackgroundThe data release included the most detailed map ever created of the cosmic microwave background. The cosmic microwave background is relic radiation from the Big Bang, and is the oldest light in our Universe – imprinted on the sky when it was just 380 000 years old. At that time, the young Universe was filled with a hot dense soup of interacting protons, electrons and photons at about 2700ºC. When the protons and electrons joined to form hydrogen atoms, the light was set free. As the Universe has expanded, this light today has been stretched out to microwave wavelengths, equivalent to a temperature of just 2.7 degrees above absolute zero. This cosmic microwave background shows tiny temperature fluctuations that correspond to regions of slightly different densities at very early times, representing the seeds of all future structure: the stars and galaxies of today.

Amazing anomalies

Overall, the information extracted from Planck’s new map provides an excellent confirmation of the standard model of cosmology at an unprecedented accuracy, setting a new benchmark in our manifest of the contents of the Universe. But, Planck has also revealed remarkable anomalies in the cosmic microwave background.

One anomaly is an asymmetry in the average temperatures on opposite hemispheres of the sky, in contradiction with the prediction made by the cosmological standard model that the Universe should be broadly similar in any direction we look. Other anomalies include parity asymmetry (a subject extensively investigated at the Discovery Center), a cold spot that extends over a patch of sky that is much larger than expected and alignment of certain multipoles which indicates a possible preferred direction of the Universe.

Fordeling af stof i universet. Målinger før og efter Planck

New cosmic recipe

Planck has also rewritten the cosmic recipe of what makes up our Universe. Normal matter that makes up stars and galaxies contributes just 4.9% of the mass/energy density of the Universe. Dark matter, which has thus far only been detected indirectly by its gravitational influence, makes up 26.8%, nearly a fifth more than the previous estimate. Conversely, dark energy, a mysterious force thought to be responsible for accelerating the expansion of the Universe, accounts for less than previously thought.

Finally, the Planck data also set a new value for the rate at which the Universe is expanding today, known as the Hubble constant. At 67.15 kilometres per second per megaparsec, this is significantly less than the current standard value in astronomy. The data imply that the age of the Universe is 13.82 billion years.

This is the beginning of a new journey and we expect that our continued analysis of Planck data will help shed light on this conundrum.

More on Planck and CMB

More on the CMB and matter distribution in the Universe

CMB and inflation