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PERSONAL TECHNOLOGY | IN DEVELOPMENT / KATHLEEN WIEGNER

Facts Beyond the Fiction of 'Chain Reaction'

September 02, 1996|KATHLEEN WIEGNER

In the current movie "Chain Reaction," Keanu Reeves and Morgan Freeman play members of a scientific team that devises a way to produce significant amounts of energy from a process known as "sonoluminescence." The story may be fiction, but there is real physics involved in the notion of converting sound energy to light energy.

Sonoluminescence is a process that transforms sound energy into light energy by concentrating sound by a factor of more than a trillion. This concentration creates light flashes that are 50-trillionths of a second or shorter and generates local temperatures far hotter than those on the surface of the sun.

Sonoluminescence is created by aiming ultrasonic waves at an air bubble in a small water cylinder. The sound waves cause the bubble to oscillate furiously, which in turn causes it to expand. But as it gets larger, a near-vacuum is created inside because of the relatively few air molecules that are present.

That causes the bubble to collapse dramatically, and during this compression phase, a flash of light emerges from the bubble. Physicists estimate the collapse produces temperatures of about 10,000 degrees Kelvin, much hotter than the sun's surface.

Being a movie in need of drama, however, "Chain Reaction" departs from science, since sonoluminescence will not generate lots of energy any time soon. In the movie, the scientists discover an inexpensive way to extract hydrogen from water. A process known as electrolysis does split the hydrogen and oxygen molecules in water, but using sonoluminescence to generate electrolysis would be very difficult to do--perhaps impossible.

Some scientists suspect that sonoluminescence may have the potential to create small amounts of nuclear fusion energy. However, such fusion reactions, if they occurred at all, would not produce energy to power a city. Still, getting nuclear fusion energy from sound waves would rank as an amazing feat. But not as amazing as the science in "Chain Reaction."

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It's the Floor: According to the American Academy of Orthopedic Surgeons, of the more than 3 million sports injuries reported last year, almost 700,000 happened on the basketball court. That makes basketball the most dangerous sport, ahead of football, snow skiing, skating and baseball.

Part of the problem is underfoot. A good floor gives players the bounce they need for those skyhooks. A dead floor puts them at risk for injury.

Oddly enough, little information exists about what makes a good floor. But Robbins Inc., the Cincinnati-based company that supplies flooring for the majority of NBA teams and provided floors for the nine venues at this year's Olympic Games in Atlanta, is funding research at Purdue University to come up with standards for wood floors.

Most basketball floors are made of northern hard maple. But wood is challenging from an engineering standpoint, because it's an organic material that is affected by age, temperature and moisture. Researchers have found that the uniformity of the floor can be as important as overall ability to disperse the force of the player's landing.

Floors that aren't uniform are more of a problem than floors that don't absorb impact adequately. In the near future, specifications for proper flooring could be established, which would, in turn, lead to regular testing. Sections of a floor that weren't performing adequately could then be replaced.

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I See 3-D: One of the problems with many robots and other automated systems equipped with artificial vision is that their eyes "see" the world as two-dimensional. As a result, they have a lot of trouble assessing the relative positions of objects.

Some robots can reconstruct 3-D images, but the process tends to be slow and cumbersome. Now two physicists from the Weizmann Institute in Israel have developed a 3-D imaging technique that speeds up and simplifies the process.

The system uses two regular video cameras, a light source and a transparent fluorescent screen placed between the cameras and the object to be filmed. When light is reflected off the object, it strikes the screen and creates a flash that the cameras record along with the image of the object.

One camera films continuously, and the other has a shutter that opens for only a billionth of a second at a time, registering just a tiny fraction of the light particles emitted by the flashes. Because both the speed of light and the time it takes for the flashes to fade on the screen are known, it is possible to determine the exact distance between the screen and each point on the object's surface.

This information, in turn, is combined with data from the picture of the filmed object to form a 3-D image. The system can be applied in such diverse fields as aerial photography, cartography and surveying.

Freelance writer Kathleen Wiegner can be reached at kkwrite@aol.com

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