Physics

Nanomechanical oscillators -- tiny strips of vibrating silicon only a few hundred atoms thick -- are the subject of extensive study by nanotechnology researchers. They could someday replace bulky quartz crystals in electronic circuits or be used to detect and identify bacteria and viruses.

The catch is that measuring their vibrations isn't easy. It is usually done by bouncing laser beams off them -- which won't work when the nanodevices become smaller than the wavelength of the light -- or with piezoelectric devices -- those bulky quartz crystals we're trying to get rid of.


Schematic of the experimental setup.

Researchers in Japan have developed a pair of molecular-scale scissors that open and close in response to light. The tiny scissors are the first example of a molecular machine capable of mechanically manipulating molecules by using light, the scientists say.

The scissors measure just three nanometers in length, small enough to deliver drugs into cells or manipulate genes and other biological molecules, says principal investigator Takuzo Aida, Ph.D., professor of chemistry and biotechnology at the University of Tokyo.


The scissors-like molecular machine extends or folds in response to different wavelengths of light. Credit: University of Tokyo.

As an electromagnetics guy I stay in touch with a lot of what is happening in that segment of physics by subscribing to plain, ol' email lists. People who need info just fire off a question to the group and someone helps.

Occasionally recruiters spam the place because, you know, all of their recruiting emails are terribly important to the whole planet. When I got my email this morning, I saw this:

University of Chicago scientists will demonstrate how to incinerate a white dwarf star in unprecedented detail at the “Paths to Exploding Stars” conference on Thursday, March 22, in Santa Barbara, Calif.

White dwarf stars pack one and a half times the mass of the sun into an object the size of Earth. When they burn out, the ensuing explosion produces a type of supernova that astrophysicists believe manufactures most of the iron in the universe.

A new nanoscale apparatus developed at JILA—a tiny gold beam whose 40 million vibrations per second are measured by hopping electrons—offers the potential for a 500-fold increase in the speed of scanning tunneling microscopes (STM), perhaps paving the way for scientists to watch atoms vibrate in high definition in real time.


This slow-motion simulation of the JILA nanoscale motion detector shows the wiggling of a floppy metal beam, just 100 nanometers thick, as it is struck by an electric current at the dot. Red indicates the greatest change in position from the rest state. Credit: Credit: K. Lehnert/JILA

Despite advances in experimental nuclear physics, the most detailed probing of atomic nuclei still requires heavy doses of advanced nuclear theory. The problem is that using theory to make meaningful predictions requires massive datasets that tax even high-powered supercomputers.

In a March 16 Physical Review Letters article, researchers from Michigan State and Central Michigan universities report dramatic success in stripping away much of this stubborn complexity. The advance, which slashes computational time from days or weeks to minutes or hours, may help address one of the most important questions in nuclear physics today: what is the structure of heavy atomic nuclei?

For the first time, scientists of the BaBar experiment at the Department of Energy's Stanford Linear Accelerator Center (SLAC) have observed the transition of one type of particle, the neutral D-meson, into its antimatter particle. This observation will now be used as a test of the Standard Model, the current theory that best describes all the universe's luminous matter and its associated forces.


Silicon Vertex Tracker. The SVT is the heart of the BABAR experiment at SLAC—in the photo, physicists are putting the finishing touches on improvements to the detector. (Photo Courtesy of Peter Ginter)

Work completed by a visiting research professor at Rowan University, physics professors and a student from the institution shows that light is made of particles and waves, a finding that refutes a common belief held for about 80 years.

Shahriar S. Afshar, the visiting professor who is currently at Boston's Institute for Radiation-Induced Mass Studies (IRIMS), led a team, including Rowan physics professors Drs.

Quantum gravity is the holy grail of theoretical physics in the 21st century. The frustrating thing about the search for it is that the window in which we could experimentally access quantum effects of gravity is very far away from what we can reach. It would take particle energies as high as 1016 TeV to access them. That is 15 orders of magnitude higher than what even the Large Hadron Collider - The World's largest Microscope - will probe. Alternatively, one had to examine distances as small as 10-20femtometers!

Understanding the origin and behavior of the magnetic fields of planets and stars is the goal of research being carried out by many teams from all over the world. The VKS1 collaboration (CEA2, CNRS3,4, Ecole normale supérieure in Lyon3, Ecole normale supérieure in Paris4) has succeeded in creating in the laboratory a magnetic field in a highly turbulent flow of liquid sodium. Although the extreme conditions specific to astrophysical and geophysical environments cannot all be reproduced in the laboratory, the magnetic field observed shows remarkable similarities with magnetic fields observed in the cosmos. The findings represent a significant advance in the understanding of the mechanisms at work in the formation of natural magnetic fields.