Planck mission brings universe into sharp focus
The European Space Agency’s Planck space mission has released the most accurate and detailed map
ever made of the oldest light in the universe, revealing
new information about its age, contents and origins.
The map results suggest the universe is expanding
more slowly than scientists thought, and is 13.8 billion
years old, 100 million years older than previous estimates. The data also show there is less dark energy
and more matter, both normal and dark matter, in the
universe than previously known. Dark matter is an invisible substance that can only be seen through the
effects of its gravity, while dark energy is pushing our
universe apart.
“Astronomers worldwide have been on the edge of
their seats waiting for this map,” said Joan Centrella,
Planck program scientist at NASA. “These measurements
are profoundly important to many areas of science.”
The map, based on the mission’s first 15.5 months of
all-sky observations, reveals tiny temperature fluctuations in the cosmic microwave background, ancient
light that has traveled for billions of years from the very
early universe to reach us. The patterns of light represent the seeds of galaxies and clusters of galaxies.
“As that ancient light travels to us, matter acts like
an obstacle course getting in its way and changing
the patterns slightly,” said Charles Lawrence, the U.S.
project scientist for Planck at NASA’s Jet Propulsion
Laboratory. “The Planck map reveals not only the very
young universe, but also matter, including dark matter,
everywhere in the universe.”
The age, contents and other fundamental traits of
our universe are described in a simple model developed by scientists, called the standard model of cosmology. These new data have allowed scientists to test
This map shows the oldest light in our universe, as detected with
by the Planck mission. The ancient li ght, called the cosmic microwave background, was imprinted on the sky when the universe was
370,000 years old. It shows tiny temperature fluctuations that correspond to regions of slightly different densities, representing the
seeds of the stars and galaxies of today.
Image: ESA and the Planck Collaboration
and improve the accuracy of this model. At the same
time, some curious features are observed that don’t
quite fit with the simple picture. For example, the model assumes the sky is the same everywhere, but the light
patterns are asymmetrical, and there is a spot extending over a patch of sky that is larger than expected.
“On 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,” said Jan Tauber,
the European Space Agency’s Planck project scientist
based in the Netherlands. “This is the beginning of a
new journey, and we expect our continued analysis of
Planck data will help shed light on this conundrum.”
Supercomputer helps mission expose ancient light
Like archeologists carefully digging for fossils, scientists with the
Planck mission are sifting through
cosmic clutter to find the most ancient light in the universe.
The task is more complex than excavating fossils because just about
everything in our universe lies between us and the light. Complicating matters further is “noise” from
the Planck detectors that must be
taken into account. That’s where a
supercomputer helps out.
“So far, Planck has made about
a trillion observations of a billion
points on the sky,” said Julian Borrill of the Lawrence Berkeley National Laboratory. “Understanding
www.RocketSTEM.org
this sheer volume of data requires a
state-of-the-art supercomputer.”
Planck scientists have been accessing the supercomputers at the
Department of Energy’s National
Energy Research Scientific Computing Center. This computer makes
more than a quintillion calculations
per second, placing it among the
fastest in the world.
One of the most complex aspects of analyzing the Planck data
involves the noise from its detectors.
To detect the incredibly faint cosmic
microwave background, these detectors are made of extremely sensitive materials. When the detectors
pick up light from one part of the
sky, they don’t reset afterwards to a
neutral state, but instead, they sort
of buzz for a bit like the ringing of a
bell. This buzzing affects observations
made at the next part of the sky.
This noise must be understood,
and corrected for, at each of the
billion points observed repeatedly
by Planck. The supercomputer runs
simulations of how Planck would
observe the entire sky under different conditions, allowing the team
to identify and isolate the noise.
Another challenge is carefully
teasing apart the signal of the relic
radiation from the material lying in
the foreground, but one that a supercomputer can handle.
59
59