Browse Physics

Scott Pratt, Physics 1, 29 (2008) – Published October 13, 2008

Particles & Fields Nuclear Physics Interdisciplinary Physics

Energetic particle jets created in relativistic heavy-ion collisions might create detectable shock waves as they travel through the quark-gluon plasma.

Joseph J. Niemela, Physics 1, 26 (2008) – Published October 6, 2008

Superfluidity Quantum Mechanics Fluid Dynamics

Images of vortex motion in superfluid helium reveal connections between quantum and classical turbulence and may lead to an understanding of complex flows in both superfluids and ordinary fluids.

Rembert Duine, Physics 1, 27 (2008) – Published October 6, 2008

Atomic & Molecular Physics

Spin dependence of atomic and electronic interactions can give rise to propagating regions of aligned spins in solids called spin waves. These have now been observed in a gas of ultracold fermionic atoms.

Hendrick L. Bethlem, Physics 1, 25 (2008) – Published September 29, 2008

Atomic & Molecular Physics

Paramagnetic atoms and molecules experience a force in a magnetic field and scientists have now used this force to decelerate and trap hydrogen atoms. This method promises new opportunities for precision measurements on hydrogen isotopes and may be applied to a host of atoms and molecules for which existing cooling techniques fail.

Simon Cornish, Physics 1, 24 (2008) – Published September 25, 2008

Atomic & Molecular Physics

Atoms colliding in a magnetic field can form weakly bound states called Feshbach molecules. These states have now been used in combination with advanced laser techniques to create tightly bound ground-state molecules close to quantum degeneracy.

Norman J. Wagner, Physics 1, 22 (2008) – Published September 22, 2008

Soft Matter

A shear force can melt a colloidal glass, causing it to flow in a highly nonlinear fashion. Physicists have now found a way to put the description of this type of flow on a more formal theoretical footing.

Jeremy L. O’Brien, Physics 1, 23 (2008) – Published September 22, 2008

Quantum Information Optics

Laser beams made up of millions of sharply defined and coherently locked optical frequencies, called optical frequency combs, may provide a way to implement a powerful quantum computer.

Dung-Hai Lee, Physics 1, 19 (2008) – Published September 15, 2008

Superconductivity

Discovering superconductivity above room temperature is a dream for modern science and technology. Now, theorists propose that for certain types of superconductors, contact with a metal layer could greatly increase the transition temperatures of these materials—in some cases by as much as an order of magnitude.

John Pendry, Physics 1, 20 (2008) – Published September 15, 2008

Optics

Thick layers of disordered materials, such as milk or snow, scatter light so that very little of it gets through. Theorists say that a properly designed combination of incident light waves would be almost completely transmitted and we now have experimental proof of this remarkable result.

Detlef Lohse, Physics 1, 18 (2008) – Published September 8, 2008

Fluid Dynamics

A novel dimensionless parameter allows prediction of whether dispersed particles in a turbulent flow enhance or attenuate the turbulence.

Mathias Kläui, Physics 1, 17 (2008) – Published September 2, 2008

Magnetism Nanophysics

Most applications based on magnetism are incompatible with domain walls, which interrupt a homogeneous magnetization. Scientists are turning this view around as they discover new ways to use an electric current to manipulate and store information in nanoscale domain walls.

Vincent Crespi, Physics 1, 15 (2008) – Published August 25, 2008

Mesoscopics Graphene

Graphene has been idealized as a two-dimensional electron system in which the electrons behave like massless fermions, but how “perfect” is it? Scientists now show they can prepare free-standing sheets of graphene that have some of the highest electron mobilities of any inorganic semiconductor.

Sébastien Balibar, Physics 1, 16 (2008) – Published August 25, 2008

Superfluidity

Experiments indicate that, as in a superfluid, mass can flow through solid helium-4 without viscous resistance. Recent calculations shed light on how this may happen thanks to defects in the crystal lattice.

Maciej Lewenstein, Physics 1, 13 (2008) – Published August 18, 2008

Atomic & Molecular Physics

A Bose-Einstein condensate (BEC) can dramatically collapse and explode when the interactions between the atoms are sufficiently strong and attractive. Now, scientists have imaged the anisotropic, clover-leaf shape of such a collapsing gas when the attractive atomic interactions are strongly dipolar.

Michael E. Peskin, Physics 1, 14 (2008) – Published August 18, 2008

Particles & Fields Astrophysics Accelerators

New arguments based on astrophysical phenomena constrain the possibility that dangerous black holes will be produced at the CERN Large Hadron Collider.

Stephen Godfrey, Physics 1, 11 (2008) – Published August 11, 2008

Particles & Fields

The BABAR collaboration at SLAC has observed the radiative decay of an excited state of bottomonium (the bound state of a bottom quark and its antiparticle) to its ground state ηb. Observing this long-sought ground state should enable better tests of quantum chromodynamic calculations of quark interactions and the computational approach called lattice quantum chromodynamics.

Joseph B. Natowitz, Physics 1, 12 (2008) – Published August 11, 2008

Nuclear Physics

Heavy nuclei formed by fusion reactions often decay rapidly by fissioning into two fragments. Understanding how these decays occur and over what time scale provides a means to locate the superheavy “island of stability.”

Michael L. Cherry, Physics 1, 9 (2008) – Published August 4, 2008

Particles & Fields Astrophysics

Forty years ago, it was predicted that there would be a sharp cutoff in the intensity of the very-high-energy cosmic rays that strike the earth’s surface. Two collaborations—the HiRes and Auger telescopes—are providing compelling evidence for this so-called “GZK effect.”

Shamit Kachru, Physics 1, 10 (2008) – Published August 4, 2008

Atomic & Molecular Physics String Theory

Results from string theory, generalizing the anti-de Sitter/conformal field theory correspondence, may offer a fresh set of mathematical tools for understanding some kinds of phase transitions that occur in cold atomic systems.

Hélène Bouchiat, Physics 1, 7 (2008) – Published July 28, 2008

Mesoscopics

A decade ago, experimentalists showed that persistent currents can flow in nonsuperconducting mesoscopic metal rings, but there was no theory that correctly explained the magnitude or direction of the unexpectedly large currents. Theorists are now proposing a simple idea that may at last explain these results.

Igor M. Sokolov, Physics 1, 8 (2008) – Published July 28, 2008

Statistical Mechanics Biological Physics

Current technology permits tracking single molecules with exquisite precision, but the results need to be interpreted with care. Long-duration measurement of the motion of a single particle yields information that is different and complementary to that obtained from an ensemble average of many particles.

Shou-cheng Zhang, Physics 1, 6 (2008) – Published July 23, 2008

Quantum Mechanics Semiconductor Physics

Electrons in graphene can be described by the relativistic Dirac equation for massless fermions and exhibit a host of unusual properties. The surfaces of certain band insulators—called topological insulators—can be described in a similar way, leading to an exotic metallic surface on an otherwise “ordinary” insulator.

Latha Venkataraman, Physics 1, 5 (2008) – Published July 21, 2008

Nanophysics

A molecule that links two metal electrodes could function like a chemically tunable miniature electronic device, provided that electrons can move easily across the molecular junction. A group in Leiden has now made highly conducting molecular junctions with benzene.

Miles Blencowe, Physics 1, 3 (2008) – Published July 14, 2008

Quantum Mechanics Gravitation

The longitudinal ringing mode of a metal bar resonator weighing approximately one metric ton has been cooled to submillikelvin temperatures with the use of active amplifier feedback. Further improvements may allow researchers to approach the quantum limit for cooling macroscopic objects.

Steve K. Lamoreaux, Physics 1, 4 (2008) – Published July 14, 2008

Quantum Mechanics Nanophysics

Modification of electromagnetic zero-point fluctuations by closely spaced conductors causes an interaction between them called the Casimir force. New experiments with nanostructured silicon substrates show that the geometry of the conducting surfaces has a large effect on this force.