New Boomerang Findings Reveal “Music” of the Early Universe
An international team of cosmologists has begun to hear
the “music of creation” in its discovery of acoustic “notes”
in the sound waves that rippled through the universe not long
after the Big Bang.
The new results — from a detailed analysis of high-
resolution images obtained by the BOOMERANG (Balloon
Observations of Millimetric Extragalactic Radiation and
Geophysics) experiment — provide the most precise
measurement to date of several of the key characteristics
which cosmologists use to describe the universe.
BOOMERANG is an extremely sensitive microwave telescope
suspended from a balloon that circumnavigated the Antarctic
in late 1998. The balloon carried the telescope at an
altitude of almost 37 kilometers (120,000 feet) for 10 1/2
days. The images were published just one year ago. A more
detailed analysis of these maps provided the new results,
which were presented today at the American Physical Society
Spring Meeting in Washington, DC.
“The early universe is full of sound waves compressing and
rarefying matter and light, much like sound waves compress
and rarefy air inside a flute or trumpet,” said Italian team
leader Paolo deBernardis. “For the first time the new data
show clearly the harmonics of these waves.”
Cosmologists believe the universe was created approximately
12-15 billion years ago in an enormous explosion called the
Big Bang. The intense heat that filled the embryonic universe
is still detectable today as a faint glow of microwave
radiation known as the cosmic microwave background (CMB)
which is visible in all directions. Whatever structures were
present in the very early universe would leave their mark
imprinted as a very faint pattern of brightness variations in
the CMB.
The cosmic microwave background was first discovered by a
ground-based radio telescope in 1965. Within a few years,
Russian and American theorists had independently predicted
that the size and amplitude of structures that developed in
the early universe would form what mathematicians call a
“harmonic series” of structure imprinted on the CMB. In 1991,
NASA’s Cosmic Background Explorer satellite (COBE) discovered
the first evidence for structure of any sort in the CMB.
The BOOMERANG images are the first to bring the cosmic
microwave background into sharp focus. The images reveal
hundreds of complex regions visible as tiny variations —
typically only 100 millionths of a degree — in the
temperature of the CMB. The new results show the first
evidence for a harmonic series of angular scales on which
structure is most pronounced.
The presence of these harmonic peaks bolsters the theory that
the universe grew from a tiny subatomic region during a
period of violent expansion a split second after the Big
Bang. “Just as the difference in harmonic content allows us
to distinguish between a flute or trumpet playing the same
note, so the details of the harmonic content imprinted in the
CMB allow us to understand the detailed nature of the
universe,” said lead author Barth Netterfield, of the
University of Toronto in Canada.
Last April, the BOOMERANG team was able to reveal only one
harmonic peak, said U.S. team leader, Andrew Lange, of the
California Institute of Technology, Pasadena. “Using a music
analogy, last year we could tell what note we were seeing —
if it was C sharp or F flat. Now, we see not just one, but
three of these peaks and can tell not only which note is
being played, but also what instrument is playing it — we
can begin to hear in detail the music of creation,” he said.
The images obtained cover about three percent of the sky. The
BOOMERANG team plans another campaign to the Antarctic in the
near future, this time to map even fainter images encoded in
the polarization of the cosmic microwave background. The
scientific payoff of such measurements “promises to be
enormous” said U.S. team leader of the new effort, John Ruhl,
of the University of California at Santa Barbara. “With
today’s results we know for sure that the music is there and
we can interpret it. There is no doubt that by listening
carefully, and in new ways, we will learn even more.”
The 36 team members come from 16 universities and
organizations in Canada, Italy, the United Kingdom and the
United States. Primary support for the BOOMERANG project
comes from NASA and the National Science Foundation in the
United States; the Italian Space Agency, Italian Antarctic
Research Programme, and the University of Rome “La Sapienza”
in Italy; and from the Particle Physics and Astronomy
Research Council in the United Kingdom.
For more information on and images from BOOMERANG, see:
http://www.physics.ucsb.edu/~boomerang/
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