- A new analysis of the "echo" of the Big Bang
has left cosmologists scratching their heads and could throw a monkey wrench
into efforts to understand how the universe began.
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- U.S. and European scientists analyzed the distribution
of "hot" and "cold" regions -- areas that are putting
out greater or less amounts of energy than the average -- of the cosmic
microwave background radiation (the so-called echo). What they found was
unexpected: an apparent correlation between those hot and cold spots and
the orientation and motion of our solar system.
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- "All of this is mysterious," says Glenn Starkman,
a Canadian physicist based at Case Western Reserve University in Cleveland
and one of the authors of a recent paper in Physical Review Letters that
outlined the finding. "And the strange thing is, the more you delve
into it, the more mysteries you find."
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- The study, by Case Western scientists and the European
Centre for Nuclear Research in Geneva, is based on data from the WMAP satellite,
the NASA spacecraft that began mapping the cosmic microwave background
(CMB) radiation in fine detail in 2001.
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- The observed correlation is troubling on several fronts.
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- First of all, there is no reason to believe that the
finding reflects any physical connection between our local astronomical
neighbourhood and the universe at large.
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- As Dr. Starkman puts it: "None of us believe that
the universe knows about the solar system, or that the solar system knows
about the universe."
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- Far more plausible, he says, is that something within
our solar system is producing or absorbing microwaves. That means that
anyone doing cosmology would have to take into account such "local"
contamination.
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- (The correlation involves the largest-scale fluctuations
of the CMB radiation. If some of those fluctuations are a local rather
than a cosmological phenomenon, it would mean that the truly cosmological
large-scale fluctuations are even less intense than previously thought.)
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- There is, however, another possibility: The patterns
seen by Dr. Starkman and his colleagues might simply be a fluke -- an accidental
alignment between the solar system and patterns in the CMB radiation.
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- If the correlation is real, however, it could cast doubt
on the popular "inflation" model of the early universe. That
model, which builds on the well-established Big Bang theory, says the universe
underwent a period of incredibly rapid, exponential growth in the first
split-second of its existence.
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- One of its predictions is that the universe should be
nearly perfectly "smooth," that the CMB fluctuations should be
equally intense at all scales.
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- An analogy with a musical instrument can be helpful:
If you hit a drum, you hear many tones at the same time -- a primary tone
as well as many overtones, or "harmonics." The inflation model
predicts that all the overtones in the CMB should be equally intense, but
instead "we're missing the bass," Dr. Starkman says. "And
what bass there is seems to be not generated by the universe, but by something
local."
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- Other physicists are responding with caution to the finding.
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- "There is no way to judge the real significance
of such a result," says Charles Bennett of NASA's Goddard Space Flight
Center in Greenbelt, Md., the leader of the WMAP team.
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- It all depends on how we perceive "chance,"
and how we evaluate probabilities, Dr. Bennett says. The alignments seen
in the CMB may seem unlikely, he says, but that doesn't necessarily mean
that they require new physics to explain them.
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- He points out that "improbable things happen frequently
because there are lots of opportunities for them to occur." In other
words, he says, the newly discovered CMB correlations are most likely the
product of chance.
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- Dan Falk is a science journalist based in Toronto.
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- http://www.theglobeandmail.com/
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