Case physicist detects solar system corrupted cosmological data
Starkman, collaborators may change cosmologists'
understanding of when the oldest stars in our universe
might have formed
February 21, 2005 | For more information: Susan
Griffith (216)-368-1004
 Recent findings from Case Western Reserve University physicists and
their collaborators may change cosmologists' understanding of when the
oldest stars in our universe might have formed.
Glenn Starkman, Armington Professor of Physics and Astronomy at Case,
and collaborators Craig Copi (Case), Dragan Huterer (then at Case, now
Hubble Fellow at the University of Chicago), and Dominik Schwarz (then
at CERN, now at the University of Bielfeld) have been studying cosmic
microwave background (CMB) radiation—the afterglow radiation left
over from the early ages of the universe.
The researchers published their study "Are the Low Notes of the
Microwave Background Cosmic?" recently in the journal, Physical
Review Letters.
The CMB has been called by some as the most conclusive piece of evidence
of the Big Bang theory—the idea that the universe was created some
10 to 20 billion years ago in a hot and dense state and has been expanding
and cooling since then.
The temperature of the CMB is extremely uniform all over the sky.
However, tiny temperature variations or fluctuations (at the part per
hundred thousand level) can offer great insight into the origin, evolution
and content of the universe. These temperature variations were first
seen in the early 1990's by instruments aboard the Cosmic Background
Explorer (COBE) satellite. In the intervening years they have been studied
over small portions of the sky by numerous ground and balloon-based
experiments, but recently the Wilkinson Microwave Anistropy Probe produced
a new all-sky map of the CMB.
Cosmologists express these temperature fluctuations as notes on a spherical
drum. An all-sky map allows cosmologists to study
the lowest notes of the CMB—the fluctuations over the largest angles.
One of the outstanding mysteries presented by the CMB—first noticed
by COBE and now confirmed by WMAP—is that the lowest
of these notes of the universe seem to be nearly missing.
Intriguingly, Starkman and colleagues have found that what little there
is of these notes, seems to be rung by the solar system itself, and
not by the early universe.
Back when our universe was only a mere 300,000 years old, it was much
hotter and denser. At that point electrons were not bound to atoms,
Starkman said. As the universe expanded and cooled, it went from an
opaque, cloudy environment to the transparent one we see today. At that
time, most of the photons in the universe were freed from the dense
plasma and became free to travel through the expanding universe.
In the nearly 14 billion years since then, these photons have been
stretched by the expanding universe so that instead
of being photons of visible light, they are now
microwaves, the so-called CMB. Yet, these photons
still carry the imprints of the small differences
in the temperature and density of their local environment—differences
which later grew into the galaxies and clusters of galaxies we now seen
in the universe, said Starkman.
These small differences were first measured in 1991 by instruments
aboard the COBE satellite. This satellite produced the very first maps
of the CMB.
With its improved technology, WMAP's map is of far higher resolution
and quality, Starkman said. The properties of this map have excited
the cosmology community over the last two years.
Now, a new analysis of the WMAP map of the CMB shows that patterns
in the map align in unexpected ways with the shape of the solar system.
In 1991, researchers had noticed that data from the COBE satellite
showed that the bass or very lowest notes in the universe were of very
low intensity. Over the years, that information had mostly been forgotten,
said Starkman. When WMAP provided more accurate maps of the microwave
sky, the weakness of these bass notes was confirmed.
The "low note" fluctuations, according to Starkman, seem
to be contaminated by a signal coming from the solar system itself or
its neighborhood. In addition to changing our understanding of when
the oldest stars in our universe may have formed, it could also challenge
the standard "inflation" theory for the vast size and incredible
smoothness of the universe and for the properties of the structures
it contains, Starkman said.
The researchers decided to look beyond just the "volume" of
each note. In their investigation, they assigned to each note (or for
physicists, each multipole component of the CMB sky) a certain number
of directions, called multipole vectors, with the lower notes having
fewer directions.
"We found that the multipole vectors of the quadrupole and the
octopole (the two lowest interesting groups of notes) were aligned in
such a way that they knew about the ecliptic poles, which form the axis
perpendicular to the plane of our solar system," reported Starkman. "They
also seemed toknow about the solar system's motion through the universe."
"What is interesting to cosmologists is that the volume of the
low notes was already unusually low. This suggests
that, to the extent that we detect the low notes
to begin with, much or all of what we see is not
from the universe but from our own solar system," said Starkman. "This
means the low notes of the universe are really
missing—even more so than we thought they were."
New information about the low notes in the universe adds another conundrum
to fundamental theories of the universe, said Starkman.
In addition to the mysteries of dark matter and
of the accelerating expansion of the universe,
we must now add that whatever mechanism—inflation
or something else—generated
the structure we see in the universe, it knew not
to make anything bigger than about the distance out to which we can
see today. This might be because the universe is like a drum constrained
by its shape only to produce certain notes. This
would be important to explorations of the universe's topology, he said.
Alternately, it could be that what we are seeing is further evidence
that we don't really understand gravity on the largest scales.
About Case Western Reserve University
Case is among the nation's leading research institutions. Founded in 1826
and shaped by the unique merger of the Case Institute of Technology and Western
Reserve University, Case is distinguished by its strengths in education, research,
service, and experiential learning. Located in Cleveland, Case offers nationally
recognized programs in the Arts and Sciences, Dental Medicine, Engineering,
Law, Management, Medicine, Nursing, and Social Work. http://www.case.edu.
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