Text 667, 92 rader
Skriven 2005-12-08 18:52:29 av Herman Trivilino (1:106/2000.7)
Ärende: PNU 757
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PHYSICS NEWS UPDATE                                                            

The American Institute of Physics Bulletin of Physics News
Number 757  December 7, 2005  by Phillip F. Schewe, Ben Stein
                        
THE TOP PHYSICS STORIES FOR 2005.  At the Relativistic Heavy Ion
Collider (RHIC) on Long Island, the four large detector groups
agreed, for the first time, on a consensus interpretation of several
year's worth of high-energy ion collisions: the fireball made in
these collisions---a sort of stand-in for the primordial universe
only a few microseconds after the big bang---was not a gas of weakly
interacting quarks and gluons as earlier expected, but something
more like a liquid of strongly interacting quarks and gluons
(www.aip.org/pnu/2005/split/728-1.html ).  Other top physics stories
for 2005 include, in general chronological order of their appearance
throughout the year, the following: the arrival of the Cassini
spacecraft at Saturn and the successful landing of the Huygens probe
on the moon Titan (http://www.aip.org/pnu/2005/split/716-1.html );
the development of lasing in silicon (Nature, 17 February); the
biggest burst of light ever recorded from outside the solar system,
from a soft gamma  repeater
(http://www.aip.org/pnu/2005/split/721-1.html ); further evidence
for superfluid behavior in a solid
(http://www.aip.org/pnu/2005/split/724-2.html ); detection of
infrared radiation directly from an exoplanet
(http://www.aip.org/pnu/2005/split/724-1.html ); zeptogram mass
sensitivity in a cantilever sensor
(http://www.aip.org/pnu/2005/split/725-1.html ); spashless impact of
droplets at low pressures
(http://www.aip.org/pnu/2005/split/725-3.html ); the demonstration
of pyrofusion, fusion reactions created with a pyroelectric crystal
(http://www.aip.org/pnu/2005/split/729-1.html ); the best yet
prediction of hadron masses using lattice QCD
(http://www.aip.org/pnu/2005/split/731-1.html ); the best
measurement yet of the weak nuclear force
(http://www.aip.org/pnu/2005/split/736-1.html ); superfluidity
directly observed in a sample of ultracold fermi atoms
(http://www.aip.org/pnu/2005/split/734-1.html ); extension of the
"comb" technique for measuring frequency (a topic pertaining to the
2005 Nobel prize in physics) into the ultraviolet
(http://www.aip.org/pnu/2005/split/735-2.html ); geoneutrinos
observed (http://www.aip.org/pnu/2005/split/739-3.html ); hybrid
atom-molecule dark states
(http://www.aip.org/pnu/2005/split/744-1.html ); using statistical
mechanics to predict the effectiveness of flu vaccines
(http://www.aip.org/pnu/2005/split/724-3.html ); hydrophobic water
(http://www.aip.org/pnu/2005/split/747-2.html ); 2005 Nobel Prize
(http://www.aip.org/pnu/2005/split/748-1.html ); molecules that walk
(http://www.aip.org/pnu/2005/split/751-2.html ); phonon Hall effect
(http://www.aip.org/pnu/2005/split/750-1.html ); short gamma ray
bursts identified as coming from in-spiraling neutron stars (Nature
6 October); hyperentangled states
(http://www.aip.org/pnu/2005/split/754-1.html ); further progress in
research concerning left-handed or negative-refraction materials,
including perfect lensing (Science 22 April), almost perfect lensing
in the mid-infrared (http://www.aip.org/pnu/2005/split/750-3.html ),
and extension of negative-index behavior into the near-infrared
region (http://www.aip.org/pnu/2005/split/756-1.html).

FRACTAL-DOMINATED CHEMISTRY.  Why does cream poured into coffee
swirl the way it does?  A new study of how chemical reactions
proceed establishes new equations for reaction rates by taking
mixing abnormalities more into account.  Many existing equations
assume efficient mixing of ingredients, but this is far from the
case.  Before reactions can take place, proper mixing has to occur,
and as two Hungarian physicists now discover in their simulations of
mixing under more realistic fluid flow conditions, reactions often
occur along a fractal frontier.  Indeed, much real-world fluid
chemistry is chaotic in nature and takes place not in general
solution but along a many-filamented fractal surface. Some previous
studies of the steady time-independent fracticality of chemical
reactions occurring in open flows, those in which fluid continuously
flows into and out of a container.  According to Gyorgy Karolyi
(Budapest University of Technology and Economics) and Tamas Tel
(Eotvos University), their new study is the first to address the
tougher problem of a closed flow, one in which the fluid remains in
the container; in this case, the resultant filamentary fractal is
not steady but instead evolves through time, gradually filling up
more and more of the container volume.  They derive the relation
between reaction rate and fractal dimensionality (the extent to
which surface of the filaments lies between that of a two
dimensional and three dimensional object).  Fractal mixing is
suspected in the disposition of several natural systems, such as
plankton in the ocean, sea ice floating in the ocean, and cloud
patterns (http://earthasart.gsfc.nasa.gov/vortices.html).  Karolyi
(karolyi@tas.me.bme.hu) suggests that the new equations might
provide new insights for those who design microfluidic devices such
as micromixers used in printing and medical equipment.  (Karolyi and
Tel, Physical Review Letters, upcoming article)

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 * Origin: Big Bang (1:106/2000.7)