Bulletin of the American Physical Society
2005 APS March Meeting
Monday–Friday, March 21–25, 2005; Los Angeles, CA
Session L6: Presenting Current Research to Undergraduates: Physical Review Focus Authors |
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Sponsoring Units: FEd Chair: David Ehrenstein, APS Room: LACC 502A |
Tuesday, March 22, 2005 2:30PM - 3:06PM |
L6.00001: Controlling the Microscopic World with Holograms Invited Speaker: An optical tweezer uses the forces exerted by a strongly focused beam of light to trap and move objects ranging in size from tens of nanometers to hundreds of micrometers. Since their introduction in 1986, optical tweezers have become a mainstay of research in biology, physical chemistry, and condensed matter physics. This presentation highlights recent advances that promise to take optical traps out of the laboratory and into the mainstream of manufacturing, medical diagnostics, and even consumer products. In particular, recently introduced techniques in computer-generated holography can create hundreds of simultaneous optical traps, each of which can be moved independently in three dimensions and can be transformed from force-exerting pincers into new all-optical tools such as torque-exerting optical vortices. By providing unprecedented access and control over the mesoscopic world, the next generation of single-beam optical traps also offers revolutionary new opportunities for fundamental and applied research. [Preview Abstract] |
Tuesday, March 22, 2005 3:06PM - 3:42PM |
L6.00002: `Wavefunction' Imaging in Complex New Materials Invited Speaker: Advanced scanning tunneling microscopy techniques now allow one to image not only the locations of the atoms in a material, but also the quantum mechanical wavefunction of the electrons which move through it. This means that one can explore directly the quantum mechanical environment within new electronic materials, learning how their exotic properties are generated at the atomic scale. I will discuss how these new `wavefunction' imaging techniques work and show several examples of studies in which they revealed startling new insights into what is actually occurring inside complex new materials. [Preview Abstract] |
Tuesday, March 22, 2005 3:42PM - 4:18PM |
L6.00003: Sonoluminescence and other energy focusing phenomena Invited Speaker: Fluids and solids that are driven off equilibrium do not return smoothly to the equilibrium state. Instead they can display a wide range of energy focusing phenomena. In sonoluminescence a sound wave passing through a fluid has its energy concentrated by 12 orders of magnitude to create ultraviolet picosecond flashes of light. For 30KHz sound waves the spectrum is a blackbody yet its size is so small as to confound theory. At the very low frequencies achieved with a water hammer the strength of a single flash can be up-scaled by 6 orders of magnitude so as to be visible to this audience, in a real time demonstration. In a ferroelectric crystal such as Lithium Tantalate the application of heat leads to the expulsion of electrons with energies that can exceed 100KeV. Upon striking a target x-rays are emitted. A crucial question relates to whether there exist experimental configurations in which these processes can be used to generate nuclear fusion. Energy focusing also plays a role in turbulence, where intermittency leads to the formation of unexpected structures. Static electricity generated by friction is another striking example of an energy focusing effect. In the 'barometer light' dragging glass through mercury at a speed of 1mm/sec leads to picosecond electrical discharges where the electrons are accelerated to over 1{\%} the speed of light. Experiments indicate that this effect is related to phenomena encompassed by everyday friction. [Preview Abstract] |
Tuesday, March 22, 2005 4:18PM - 4:54PM |
L6.00004: Stock Market Crashes and Skipped Heartbeats: Complex Systems Follow Universal Rules Invited Speaker: Stock market gyrations and heartbeat anomalies are not entirely random. They follow universal rules that physicists can understand. I will discuss some of these rules in a variety of complex systems, including social and computer networks, and the coding in DNA molecules. One theme is that extreme but rare events like stock market crashes are not entirely unexpected but fit quite normally into the proper statistical framework. [Preview Abstract] |
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