Astronomers map how light of the big bang scattered across the universe
Most detailed ever chart of cosmic microwave background confirms remarkable accuracy of current cosmological models
The most detailed map ever made of the oldest light to shine through the universe has been released by scientists at the European Space Agency (ESA).
The view of the heavens in red and blue speckles confirms with astonishing accuracy the theories cosmologists draw on to explain the evolution of the universe from a fraction of a second after the big bang.
The map reveals tiny variations in the “cosmic microwave background” or CMB – the faint glow of radiation that is left over from the earliest light to illuminate the cosmos. These primordial photons are all around us, and account for 1% of the “snow” that could be seen on untuned television sets.
The red and blue spots reveal areas where the radiation is slightly hotter or cooler than the average temperature. Areas that are cooler (blue) are more dense and become the seeds of stars and galaxies.
The director-general of Europe’s space agency, Jean-Jacques Dordain, described the new map as “a giant leap in understanding the origins of the universe.”
The size and variations in the CMB have led the Planck scientists to tweak their estimates both of the age of universe and the nature of the matter and energy strewn throughout it.
The latest data suggests the universe is expanding at a slower rate than thought, making it roughly 80m years older at 13.82bn years.
Scientists have made minor changes to the estimated make-up of the observable universe too, with normal matter now comprising slightly more, at 4.9%. There is a little more dark matter, at 26.8%, and less dark energy, at 68.3%.
In the latter cases, “dark” is synonymous with “unknown”. Dark matter is an invisible substance that appears to cling to galaxies, but whose existence can be inferred only by its gravitational pull. Dark energy is equally mysterious, and thought to drive the expansion of the universe.
The CMB is what remains of light that spread through the universe as soon as it became transparent, around 380,000 years after the big bang. Before then, a fog of particles prevented light from shining through the fledgling cosmos. As the universe expanded, that visible light was stretched into longer-wavelength microwaves.
The map provides strong support for a theory called “inflation”, which describes a brief and hair-raising period in which the early universe expanded faster than the speed of light.
“The sizes of these tiny ripples hold the key to what happened in the first trillionth of a trillionth of a second,” said Joanna Dunkley at Oxford University. “Planck has given us striking evidence that indicates they were created during this incredibly fast expansion, just after the big bang.”
Some features of the map may take many years to explain, though. The Planck map confirms a strange asymmetry in the CMB that has mystified cosmologists. The planets in the solar system all orbit in the same plane, but the microwave background looks different above and below. Just on the horizon in the northern hemisphere is an unusual “cold spot” in the CMB that is equally baffling.
“Our ultimate goal would be to construct a new model that predicts the anomalies and links them together. But these are early days. So far, we don’t know whether this is possible and what type of new physics might be needed. And that’s exciting,” said George Efstathiou, a Planck scientist at Cambridge University.
[Bing bang via Shutterstock]