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"Cosmic Laws Like Speed of Light Might Be Changing, a Study Finds"

An international team of astrophysicists has discovered that the basic laws of nature as understood today may be changing slightly as the universe ages, a surprising finding that could rewrite physics textbooks and challenge fundamental assumptions about the
workings of the cosmos.

The researchers used the world's largest single telescope to study
the behavior of metallic atoms in gas clouds as far away from Earth
as 12 billion light years. The observations revealed patterns of
light absorption that the team could not explain without assuming a
change in a basic constant of nature involving the strength of the
attraction between electrically charged particles.

If confirmed, the finding could mean that other constants regarded
as immutable, like the speed of light, might also have changed over
the history of the cosmos.

The work was conducted by scientists in the United States,
Australia and Britain and was led by Dr. John K. Webb of the
University of New South Wales in Sydney, Australia. It is to be
published on Aug. 27 in the field's most prestigious journal,
Physical Review Letters.

Scientists who have examined the paper have not been able to find
any obvious flaws. But because the consequences for science would
be so far-reaching and because the differences from the expected
measurements are so subtle, many scientists are expressing
skepticism that the discovery will stand the test of time, and say
they will wait for independent evidence before deciding whether the
finding is true.

On the other hand, the finding would fit with some theorists' new
views of the universe, particularly the prediction that previously
unknown dimensions might exist in the fabric of space.

Even scientists on the project have been deliberately cautious in
presenting their result. Describing the implications of what his
team observed, Dr. Webb said, "It's possible that there is a time
evolution of the laws of physics."

Dr. Webb added, "If it's correct, it's the result of a
lifetime."

Dr. Rocky Kolb, an astrophysicist at the Fermi National
Accelerator Laboratory who was not involved in the work, said the
finding could not only force revisions in cosmology, or the science
of how the universe began and later evolved, but also add credence
to an unproven theory of physics called string theory, which
predicts that extra dimensions exist.

"The implication, if it is true, would just be so enormous that
it's something people should look at and take seriously," Dr. Kolb
said. "This would upset the apple cart."

The magnitude of the change apparently observed by the group is
minute, amounting to just 1 part in 100,000 in a number called the
fine structure constant over 12 billion years. That constant, also
referred to as alpha, is defined in terms of more familiar
quantities like the speed of light and the strength of electronic
attractions within atoms.

But even that small change would rock physics and cosmology, said
Dr. Sheldon Glashow of Boston University, who received a Nobel
Prize in physics in 1979. The importance of such a discovery, Dr.
Glashow said, would rank "10 on a scale of 1 to 10."

Considering the unexpected nature of the finding, both Dr. Glashow
and Dr. Kolb said the chances were high that some more mundane
explanation for the results would turn up.

Dr. John Bahcall, an astrophysicist at the Institute for Advanced
Study in Princeton, N.J., said the complicated analysis that was
required to infer the tiny changes from the observations could — in
principle, at least — be obscuring possible errors.

"The effect does not scream out at you from the data," Dr. Bahcall
said. "You have to get down on all fours and claw through the
details to see such a small effect."

But others said that the team had been very careful and that any
unknown source of error would have to be extremely subtle to be
missed.

"If they were claiming anything less dramatic, probably most
people would find their work very careful and believable," said Dr.
Massimo Stiavelli, an astrophysicist at the Space Telescope Science
Institute in Baltimore.

"Exceptional results deserve extraordinary proof," Dr. Stiavelli
said, adding that he was reserving judgment until further evidence
became available.

The work relied on observations of light from distant beacons
called quasars, which shine with a brightness equivalent to
billions of suns. The light is probably emitted by matter torn from
young galaxies by the powerful gravity of a black hole.

Besides Dr. Webb, the team included three other scientists at the
University of New South Wales, Michael T. Murphy, Dr. Victor V.
Flambaum, and Dr. Vladimir A. Dzuba and one physicist at Cambridge
University in Britain, Dr. John D. Barrow. Three American
astronomers who are experts on quasars were also members of the
team — , Dr. Christopher W. Churchill of Pennsylvania State
University, Dr. Jason X. Prochaska of the Carnegie Observatories,
and Dr. Arthur M. Wolfe of the University of California at San
Diego.

The observations, made by the 30- foot-wide Keck Telescope on
Mauna Kea, in Hawaii, looked in detail at the absorption of quasar
light by gas clouds in deep space between Earth and the quasars.
Metal atoms like zinc and aluminum are often present in trace
amounts in the clouds.

The absorption of light by such atoms creates dark spikes at
various wavelengths in the quasar's spectrum, with a pattern so
well defined that it is often likened to a fingerprint. The value
of those wavelengths is directly related to the value of the fine
structure constant.

But the fingerprint seemed to change in time, Mr. Murphy said,
indicating that the constant grows larger as one goes nearer to the
present and was not really constant.

"What we have found is that, statistically, there is a difference
between the fine structure constant a long time ago and here on
earth," he said.

Far from being of interest only in understanding atomic behavior,
said Dr. Barrow of Cambridge University, the effect would be
important "because it gives you such a feedback into fundamental
physics."

String theory, for example, could accommodate changes in
quantities that accepted physics theory considers immutable. String
theorists postulate that space contains tiny, unseen dimensions.
Any change in the size of those dimensions — much like the
expansion of the universe in the space we are familiar with — could
change quantities like the fine structure constant, said Dr. Paul
Steinhardt, a physicist at Princeton University.

Dr. Steinhardt said most theorists would have expected those
changes to have occurred in the first seconds of the universe's
life and be virtually unobservable by astronomers today. Still, he
pointed out that several years ago, other astronomers unexpectedly
found that the present universe is apparently filled with a
mysterious kind of energy that counteracts gravity on large scales.
Perhaps the two effects are somehow related, Dr. Steinhardt said.

Other scientists pointed out that geologic processes, like
naturally occurring nuclear fission, have been used to determine
that the fine structure constant has probably changed little over
the past two billion years on Earth. But researchers on the new
paper point out that their results reach back much farther in time,
and that interpreting the geological results is also a complicated
matter.

But a few physicists, like Dr. Jacob D. Bekenstein of Hebrew
University in Israel, noted that some theories have long been
predicting a change in some of nature's apparent constants. Dr.
Bekenstein called the findings "potentially revolutionary" and said
he was inclined to believe them.

"After much thinking about this issue," Dr. Bekenstein said, "I
think the quasar observations may have found the real variation."

http://www.nytimes.com/2001/08/15/science/15PHYS.html?ex=998885276&ei=1&en=3eead33e0aa0937b

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