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Introduction


The annual March Meeting of the American Physical Society is a venue where physicists talk shop, divulging progress in fundamental research that may take a decade or more to surface as technologies that affect business. It's also where physicists discuss the practical side of their science. There were approximately 5,000 presentations at this year's conference in Indianapolis. Senior Writer Otis Port was in attendance and filed the following reports: Traditionally, physics has searched for explanations for the mysteries of existence through decomposition--chopping matter into ever-smaller components. Now, some physicists are reversing this trend. They study macro-scale features in the real world, including the complex networks that characterize life. Using statistical tools, they have been examining microbes, the vascular systems in plants, metabolic rates in animals, food chains in various ecosystems--as well as the topology of the Internet (above).

What they've found is surprisingly consistent. "Regardless of size, almost all life is sustainedby fractal-like hierarchical branching networks," said Geoffrey West, a physicist at Los Alamos National Laboratory. Fractals already are famous as one of nature's organizing principles--patterns that transcend scale, such as swirls of clouds that mirror the spirals of stars in galaxies. It will be interesting to see if fractal patterns also permeate the subatomic world. Grid computing is the poor man's supercomputer. It harnesses thousands of personal computers to work collectively on, say, finding a cure for anthrax. But the complexity of grid-computing networks pales beside what's coming: amorphous computing.

At the physics fest, computer engineers said they are turning to biology for inspiration. But the goal isn't necessarily an all-powerful computer--it's a synthetic biology for smart products and systems that mimic nature, said Gerald J. Sussman, an electrical engineer at Massachusetts Institute of Technology. One application: a lubricant with artificial cells--tiny microelectromechanical systems (MEMS). Some of these micron-size chips would function as sensors to detect changes in friction; others would calculate optimum lubricity and direct production of lubricant molecules by MEMS-size chemical plants. Another possibility would be self-repairing tissues such as cartilage.

Programming vast colonies of micromachines to work cooperatively is the main challenge. Fabricating such systems is a comparative snap, Sussman said, though "it is not yet within our grasp." To analyze the flow of traffic on freeways and streets, scientists originally turned to models of water gushing through pipes. As engineers collected more data on real-world traffic patterns, though, the inadequacies of this approach soon became apparent and spurred development of new, more detailed statistical models.

The latest "microscopic" techniques not only can simulate the movement of single cars, said physicist Michael Schreckenberg of Germany's University of Duisburg--they can also predict some aspects of driver behavior. Thus, it may soon be possible to generate continuously updated rush-hour simulations from real-time sensor data. Urban traffic managers could then flash timely warnings to drivers. But a few statistical potholes need filling, Schreckenberg said. One is integrating the two approaches, since the older models are better for some situations. Also, more accurate algorithms are needed for predicting how drivers might react to specific traffic alerts. -- At 32F, water is very sensitive to any temperature change: Raise or lower it by one degree, and water undergoes a phase transition between liquid and solid. Entire ecosystems also have such critical junctures, according to physicists at Scotland's University of Edinburgh. Their computer models reveal a potentially worrisome aspect of global warming. Rising temperatures have gradual and foreseeable results on the climate until a critical point is reached. Then there is an abrupt and dramatic phase transition--as hard to reverse as it is to predict.

-- Magnetic-resonance imaging should soon be producing new types of visuals to help neuroscientists understand how the human brain works. More efficient MRI systems may be able to measure the oxygen content of small groups of brain cells, reported E. Mark Haacke, director of the MRI Institute for Biomedical Research in St. Louis. Oxygen level is an important indicator of cell health and physiology. Thus, the new technology could be a potent diagnostic tool for physicians as well as a means of spotting clusters of brain cells gearing up to process electrical signals.

-- Boosters of ultrawideband (UWB) radio are celebrating the recent approval for wireless telecom applications. UWB would greatly expand wireless capacity. And because it carries traffic via billions of pulses every second, spreading them helter-skelter across a huge swath of frequencies, it's inherently secure. Papers at the Indianapolis conference described some interesting UWB applications--for example, peering through containers to inspect the quality of various packaged goods, or enhancing images of the birth pangs of new stars.


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