|Subj:||Study Suggests Speed of Light May Have Changed Over History of Universe|
|Date:||8/15/01 12:01:53 PM Pacific Daylight Time|
Aug 15, 2001
Study Suggests Speed of Light May Have Changed Over History
By Matt Crenson
The Associated Press
New observations from the world's biggest telescope indicate
that one of nature's supposedly immutable constants has
changed over the 15 billion-year history of the universe.
Physicists were shocked at the discovery, but pleasantly so
because it suggests that new theories about how the universe
works on the subatomic scale may be correct.
"This has fundamental implications for our understanding of
physics," said John Webb, a professor at the University of
New South Wales in Sydney, Australia.
Webb led the research team that made the discovery, which is
described in a paper to be published August 27 in Physical
The team found that the fine structure constant - a number
that determines the strength of electromagnetic force and
thus the speed of light - may have been ever so slightly
smaller billions of years ago. If true, then current
theories are incorrect because they maintain that light's
speed and other fundamental properties do not change in
either space or time.
This is actually good news to physicists, because proposed
theories can accommodate changes in the fine structure
constant over time. Known as string theories, they allow
either a 10- or 26-dimensional universe, rather than a 4-D
one containing the three spatial dimensions plus time. The
extra dimensions would be curled or folded, so they would be
impossible to detect in everyday life - or even in any
physics experiment yet conducted.
"This would be a clue to help guide how you convert string
theories into something relevant," said Gordon Kane, a
physicist at the University of Michigan. "It's just a very
nice piece of information, if it stands up."
That is a big if, said John Bahcall of the Institute for
Advanced Study in Princeton, N.J.
"I'm quite cautious about whether to believe this result,"
The physicists used the world's most powerful telescope to
peer at some of the most distant objects in the universe.
They aimed the Keck telescope atop Hawaii's Mauna Kea at 17
different quasars, which are extremely bright objects
probably associated with black holes.
The quasars are so far away - about 12 billion light-years -
that light they produced at the dawn of the universe is only
now reaching Earth.
During its long journey, the light has passed through clouds
of intergalactic gas, where some of it has been absorbed.
The patterns of absorption tell scientists something about
the gas, and something about the light as well - including
its speed and the fine structure constant that determines
how fast it goes.
"It's like a car headlight on a foggy night. The headlight
shines through the fog ... and you can see the change on the
background light because of the presence of the fog," Webb
The scientists hope to confirm their results using a
different telescope, perhaps the Very Large Telescope at the
European Southern Observatory in Chile.