From: LARRY KLAES (ljk4_at_msn.com)
Date: Fri Jan 09 2004 - 17:32:27 PST
----- Original Message -----
From: physnews_at_aip.org
Sent: Friday, January 09, 2004 1:58 PM
To: ljk4_at_MSN.COM
Subject: Physics News Update 668
PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 668 January 9, 2004 by Phillip F. Schewe, Ben Stein, and
James Riordon
LARGE GALAXIES FORMED SURPRISINGLY EARLY, a new study finds. You'd
expect that a census of the farthest, earliest galaxies would
feature a lot of smaller, hotter, younger, bluer galaxies, perhaps
in the act of smashing into and coalescing with their neighbors.
But a new survey made using the 8-meter Hawaii telescope of the
Gemini Observatory shows rather that at only a comparatively short
time after the big bang the universe was already well furnished with
large, reddish, mature elliptical galaxies. The Gemini Deep Deep
Survey (GDDS) trawled the poorly patrolled "Redshift Desert" region
of cosmic history, the epoch roughly 3 to 6 billion years since the
big bang and found instead what team member Roberto Abraham
(University of Toronto) calls a "Redshift Dessert"---plenty of
massive old galaxies where you'd expect few. Abraham and his
colleagues reported the results at this week's meeting of the
American Astronomical Society (AAS) in Atlanta.
Patrick McCarthy (Carnegie Institution) said that what the survey
shows is that at a point only 4 billion years into the life of the
universe there were already galaxies up to 3 billion years old.
This leaves very little time for the assembly of something as big as
an elliptical galaxy. Furthermore, the galaxies in the survey
possess a plentiful stock of heavier "metal" atoms, the kind that
would have to be cooked up in repeated cycles of star birth and
supernova. To put the question in term of galaxy demographics: how
could there be so many senior citizens so early? According to
Roberto Abraham, all of this should make theorists sweat.
(www.gemini.edu/gdds/)
LARGE SCALE STRUCTURES IN THE EARLY UNIVERSE are also larger than
expected. Like the presence of surprisingly early mature galaxies
at a redshift of about 2 (see the item above) another result at the
AAS meeting suggests that the standard cosmological model---or at
least that part of it devoted to galaxy formation---is in need of
revision. A group of astronomers using the Blanco Telescope of the
Inter-American Observatory in Chile and the Anglo-Australian
Telescope in Australia reported seeing a grouping of 37 galaxies,
all at a redshift close to 2.38, spread 300 million light years
across the sky. Povilas Palunas (University of Texas) said that
this constitutes the largest observed structure in the distant
universe. According to models that simulate how the hot diffuse
matter of the infant cosmos distilled into a web of knots and
filaments, such an immense agglomeration should not have arisen so
quickly.
The statistical case for saying that this sampling of bright
galaxies (fainter galaxies could not be seen) is truly a coherent
structure and not just a chance juxtaposition can be expressed as a
probability with 1000-to-1 odds, a likelihood obtained by looking
not at the specific arrangement of galaxies themselves but at the
daunting amount of void between the galaxies. Gerard Williger
(Johns Hopkins) said that he and his colleagues would naturally like
next to sample adjoining volumes of deep space in order to test the
proposition that the hasty filimentation of matter seen in this
initial data set (the observed galaxies lie in the southern
constellation "Grus") is not an isolated incident
(www.gsfc.nasa.gov/topstory/2004/filament.html).
NEGATIVELY MISBEHAVING MUONS bolster earlier evidence of new physics
beyond the standard model, though further experimental and
theoretical work may be needed to confirm this possibility. At
Brookhaven National Laboratory's "g-2" experiments, an international
collaboration has been studying the decay of the muon, a heavy
cousin of the electron, by measuring the muon's magnetic moment, a
quantity that describes the strength with which the particle
interacts with magnetic fields. In 2001, researchers studied
positively charged muons and found a discrepancy between the
experimental value and the predictions of the standard model (see
Update 524), though the discrepancy was later reduced after
researchers discovered an error in the theory. Yesterday,
researchers reported measurements on negatively charged muons that
matched the precision of the previously reported positive muon
results. Combining the data on positive and negative muons, the
researchers find a disagreement between the experiments and the
standard model of as much as 2.8 standard deviations, about the same
level of discrepancy that was originally reported in 2001 before the
theory error was discovered. (For a discussion of the meaning of
"standard deviation" and statistical significance in general, see
this past Update item:
http://www.aip.org/enews/physnews/2001/split/566-2.html.)
What would cause this discrepancy? Perhaps the muon's magnetic
moment is being influenced by hypothesized but yet-undiscovered
"supersymmetric" particles (with names such as "squarks") that are
not included in the standard model. However, further work may be
needed to check and refine the very difficult theoretical
calculations on the muon's magnetic moment. Unfortunately,
additional experiments at Brookhaven are out of the question for the
moment, as the project's funding has ended. However, experiment
spokesman Lee Roberts of Boston University says that the new results
are prompting his group to write a new proposal for continuing their
experimental tests, and future accelerator experiments, such as
those at the upcoming Large Hadron Collider in Europe, will search
for supersymmetric particles. (More information at
http://www.bnl.gov/bnlweb/pubaf/pr/2004/bnlpr010804.htm)
***********
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