2013-03-21 13:41:55
A map tracing the "oldest light" in the sky has been produced by Europe's
Planck Surveyor satellite. Its pattern confirms the Big Bang theory for the
origin of the Universe but subtle, unexpected details will require scientists
to adjust some of their ideas.
A spectacular new map of the "oldest light" in the sky has just been released
by the European Space Agency.
Scientists say its mottled pattern is an exquisite confirmation of our Big-Bang
model for the origin and evolution of the Universe.
But there are features in the picture, they add, that are unexpected and will
require ideas to be refined.
The map was assembled from 15 months' worth of data acquired by the 600m-euro
( 515m) Planck space telescope.
It details what is known as the cosmic microwave background, or CMB - a faint
glow of microwave radiation that pervades all of space.
Its precise configuration, visible in the new Planck data, is suggestive of a
cosmos that is slightly older than previously thought - one that came into
existence 13.82 billion years ago.
This is an increase of about 50 million years on earlier calculations.
The map's pattern also indicates a subtle adjustment is needed to the
Universe's inventory of contents.
It seems there is slightly more matter out there (31.7%) and slightly less
"dark energy" (68.3%), the mysterious component thought to be driving the
cosmos apart at an accelerating rate.
Planck is the third western satellite to study the CMB. The two previous
efforts - COBE and WMAP - were led by the US space agency (Nasa). The Soviets
also had an experiment in space in the 1980s that they called Relikt-1.
The CMB is the light that was finally allowed to spread out across space once
the Universe had cooled sufficiently to permit the formation of hydrogen atoms
- about 380,000 years into the life of the cosmos.
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How Planck's view hints at new physics
Planck anomalies graphic
The CMB's temperature fluctuations are put through a number of statistical
analyses
Deviations can be studied as a function of their size on the sky - their
angular scale
When compared to best-fit Big Bang models, some anomalies are evident
One shows the fluctuations on the biggest scales to be weaker than expected
Theorists will need to adjust their ideas to account for these features
It still bathes the Earth in a near-uniform glow at microwave frequencies, and
has a temperature profile that is just 2.7 degrees above absolute zero.
But it is possible to detect minute deviations in this signal, and these
fluctuations - seen as mottling in the map - are understood to reflect the
differences in the density of matter when the light parted company and set out
on its journey all those years ago.
The fluctuations can be thought of as the seeds for all the structure that
later developed in the cosmos - all the stars and galaxies.
Scientists subject the temperature deviations to a range of statistical
analyses, which can then be matched against theoretical expectations.
This allows them to rule in some models to explain the origin and evolution of
the cosmos, while ruling out a host of others.
The team that has done this for Planck's data says the map is an elegant fit
for the standard model of cosmology - the idea that the Universe started in a
hot, dense state in an incredibly small space, and then expanded and cooled.
At a fundamental level, it also supports an "add-on" to this Big Bang theory
known as inflation, which postulates that in the very first moments of its
existence the Universe opened up in an exponential manner - faster than light
itself.
But because Planck's map is so much more detailed than anything previously
obtained, it is also possible to see some anomalous features in it.
One is the finding that the temperature fluctuations, when viewed across the
biggest scales, do not match those predicted by the standard model. Their
signal is a bit weaker than expected.
There appears also to be an asymmetry in the average temperatures across the
sky; the southern hemisphere is slightly warmer than the north.
A third significant anomaly is a cold spot in the map, centred on the
constellation Eridanus, which is much bigger than would be predicted.
These features have been hinted at before by Planck's most recent predecessor -
Nasa's WMAP satellite - but are now seen with greater clarity and their
significance cemented.
A consequence will be the binning of many ideas for how inflation propagated,
as the process was first introduced in the 1980s as a way to iron out such
phenomena.
The fact that these delicate features are real will force theorists to finesse
their inflationary solutions and possibly even lead them to some novel physics
on the way.