|
Information from a telescope-attached to a stadium-size balloon
and launched in 1998 from McMurdo Station in Antarctica-splashed
across the front pages of newspapers around the world when it
discovered evidence that dark matter exists as well as that the
universe is flat. 
Directing the Boomerang Project (shortened for Balloon Observations
Of Millimetric Extragalactic Radiation and Geophysics) is John
Ruhl. Ruhl came from the University of California, Santa Barbara,
to join the CWRU faculty as a professor.
"John's arrival continues our efforts to create one of the strongest
departments in particle astrophysics in the country as part of
one of the best mid-size physics departments anywhere," said Lawrence
Krauss, chair and Ambrose Swasey Professor of Physics.
Ruhl studies the 10-12 billion-year old universe when it was
"a baby" at the age of 300,000 years. This age was an important
point in the universe's development as it transitioned from an
opaque plasmid soup of electrons, protons and photons to the clear
universe we see today. As the free electrons and protons merge
to form hydrogen atoms, the universe evolved with dense hot spots
that collapsed under gravitational forces into clusters and the
under dense, cold areas became voids.
While the universe was opaque, the photons bounced off the electrons
and protons. Once the universe cleared, billions of photons for
every electron were free to travel and continue to do so.
Ruhl's 1.3 meter cosmic microwave telescope on Boomerang is pointed
at the depths of the universe where the space archeologist maps
the photons' travels. He also has a larger land-based Acrminute
Cosmology Bolometric Array Receiver (Acbar) at the South Pole
that reads the development of smaller angles or slices of the
universe at .9 to 2.0 mm wavelength bands. Acbar's resolution
for reading information from the universe has more than twice
the resolution of the Boomerang scope-all instruments were built
by Ruhl and his research team in collaboration with other universities
in the United States, Italy and Canada.
The Boomerang microwave telescope is super sensitive to heat
from the universe and can detect these free photons in a similar
way to someone blindfolded can feel radiant heat from a fireplace
by extending their hands. Ruhl's 3,000 pounds of telescope and
related equipment in the Antarctic launch is equipped with a sensor
cooled to the temperature of .28 Kelvin and can record the presence
of these weak and faint photons.
"What we do with the telescope is to catch those photons that
are still traveling for billions of years, ever since they last
scattered off the plasma in the early universe," Ruhl said.
Results from the Boomerang Project sparked a "great hullabaloo"
in astrophysics, according to Ruhl.
"In textbook fashion, we nailed several results," he said, referring
to the findings of a characteristic scale in the size of the bright
and cold spots in the universe through what they call a power
spectrum. "These power spectra have provided a strong test of
inflation models of the early universe."
In reanalyzing Boomerang data, Ruhl and his research team also
found they could see the signatures of the oscillations going
on in the early electron and proton soup as the gravity from dark
matter impacted the plasma.
"Indirectly we can sense the dark matter by its gravitational
effects on the plasma," he said. "This was the right tool, and
what it means is that we have a solid understanding of what was
going on at that time in the early universe."
Boomerang telescope was airborne over 10 days in1998-99. Another
launch will take place in December.
"Antarctica is ideally suited for long duration ballooning,"
says Ruhl.
A stratospheric vortex at Antarctica allows the balloon to circle
the continent in 10 to 15 days, returning it near to the launch
pad for recovery.
Acbar, at the Amundsen-Scott South Pole Station, is atop a 10,000
foot polar plateau. The high altitude and cold ambient temperatures
make the Pole the best millimeter-wave observing site on the planet.
Ruhl has a third project that measures polarization in the cosmic
microwave background for a different view of the universe. This
research has the potential to confirm and improve the current
understanding of the physics of what is known about universe development
through an examination of different cosmological parameters, such
as dark matter theory, expansion of the universe or the existence
of a cosmological constant.
The projects are supported by the National Science Foundation
and the NASA and are done in collaboration with scientists from
the United States, Italy and Canada. He plans to continue this
work at CWRU.
Ruhl earned his bachelor's of art degree in 1987 from the University
of Michigan and his doctorate in physics in 1993 from Princeton
University.
|
