Number 533, March 28, 2001 by Phil
Schewe, James Riordon, and Ben Stein
A Diamond as Big as the Ritz
Life expectancy
is not the same for all quarks. The "strange" quark, for example,
is very unstable compared to the "up" and "down"
quarks. However in the exotic high-density environment inside a neutron
star, strange quarks are expected to fare better.
A new study conducted
by Krishna Rajagopal and Frank Wilczek at MIT (wilczek@mit.edu,
617-253-0284) shows how much better. Previously it was thought that
the quark-matter collective (what you get by compressing matter to extraordinary
densities, as the RHIC accelerator, but keeping it cool) consisting
of up quarks (each with an electrical charge of +2/3), down quarks (charge
-1/3) and a smaller number of strange quarks (charge -1/3) would have
an overall positive electrical charge. This in turn was expected to
attract electrons, making the quark glob metallic and opaque.
The MIT calculations
show, however, that the strange quark population to be on a par with
the ups and downs, meaning the quark-matter part of the neutron star
would be electrically neutral; it would in fact be a transparent insulator
free of electrons. "Thus it seems likely," says Wilczek, "that
inside each neutron star is a 'Diamond as big as the Ritz,' actually
much bigger, and a million billion time as dense." The core would
not be a solid or crystal in the usual sense, and would not have facets,
but it would reflect some light at its boundaries and would otherwise
look like a diamond. (Physical
Review Letters, 16 April 2001; text at Physics
News Select)
Quantum Teleportation of a Moving Atom
Quantum teleportation
involves transmitting all of the information contained in a quantum-mechanical
particle (such as a photon or atom) to another particle, even if the
two are completely separated by a large distance. Experimentally demonstrated
with photons in numerous labs, quantum teleportation schemes have up
to now focused on transmitting a particle's internal states, such as
photon polarization.
Exploring quantum
teleportation with atoms, an Israel-Germany-Czech Republic collaboration
(Tomas Opatrny, Weizmann Institute/F. Schiller University, pto@tpi.uni-jena.de)
has come up with an experimental proposal for transmitting an atom's
full information including its "external" states, such as
its energy of motion. This procedure replicates the quantum features
of the external motion of a particle.
For example, if
particle-to-be-teleported C yielded a diffraction pattern after passing
through two slits, then the same pattern would be produced by particle
B, which receives the teleported information. The researchers propose
the following idea: Dissociate a very cold molecule with a laser pulse
into two atoms (called A and B). Then, manipulate the two atoms so that
they become entangled: each one is in a fuzzy state individually but
has a precisely defined relationship with its partner. Then, let one
of the entangled particles (such as A) collide with particle C, whose
unknown state should be teleported. After their collision, the momentum
values of the collision partners A and C are measured.
With that information,
the researchers know how to "kick" and deflect atom B so that
the motion of B precisely emulates that of particle C. Teleportation
is extremely demanding, but the authors say that state-of-the-art equipment
for studying atomic collisions and quantum effects makes this experiment
"hard but feasible." (Opatrny
and Kurizki, Phys. Rev. Lett., 2 April 2001; text at Physics
News Select.)
Fluid Oxygen Becomes Metallic
Fluid oxygen becomes
metallic at a pressure of 1.2 Mbar and temperatures around 4500 K, discovered
Marina Bastea (925-424-2803, bastea1@llnl.gov),
Arthur C. Mitchell, and William J. Nellis of the Lawrence Livermore
National Laboratory (LLNL). Although other groups have reported metallic
oxygen formed by compressing the solid phase, this is the first time
anyone has managed to make a metal from the disordered liquid phase.
To create the metallic
fluid, the researchers fired a projectile at a reservoir of liquid oxygen
trapped between two single-crystal sapphire anvils. The resulting shockwaves
produced the metal-forming conditions for periods of 100-200 ns. The
experimental technique is similar to the one used by Weir et. al. at
LLNL for groundbreaking experiments leading to the first creation of
metallic hydrogen in 1996 (Update
263). The experiment should stimulate theoretical progress in the
relatively immature field of physics involving warm fluids at high densities
and pressures. (Physical
Review Letters, 2 April 2001; text at Physics
News Select.)
Most Distant Supernova
The careful
analysis of an object called 1997ff now reveals it as the most distant
supernova known, at a redshift of 1.7. Its discovery helps to fill
out the cosmological view that the current era in which the expansion
of the universe is accelerating was preceded by an era in which the
expansion had been decelerating.
Study of the
object also reduces the chances that obscuring dust might have distorted
our impression of other distant supernovas being used as standard
candles for establishing a distance scale to the remote corners of
the universe. The dust problem had stood as a possible qualification
to the interpretation that the universal expansion was not in fact
slowing down but actually gaining speed (LBL
press release, April 4, 2001).
The new observation
of four additional supernovas from the deceleration era (although
not quite as distant as the z=1.7 object) further buttresses the new
thinking (Science News,
31 March 2001).
The Biggest Quasar Survey Ever
The biggest quasar survey ever, constituting an inventory of more
than 11,000 objects, reveals that the clustering of quasars even at
early times in the history of the universe was surprisingly consistent
with quasar densities much later. This result, coming out of the Two-Degree
Field (2dF) quasar survey conducted with the Anglo-Australian Telescope,
was reported today at two separate meetings: by Robert Smith of Liverpool
John Moores University at the UK National Astronomy Meeting in Cambridge,
UK; and by Tom Shanks of the University of Durham at The Dark Universe
symposium at the Space Telescope Science Institute in Baltimore. (RAS
press release, April 4)
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