STRANGE BUT TRUE- Quashing twinkling: How to stop a star's shimmer


DRAWING BY DEBORAH DERR McCLINTOCK

Q. "Twinkle, twinkle little star..." Stars scintillate because disturbances in the atmosphere bend the points of light erratically. How might you make our sun twinkle? –L. Digges

A. Here's one (elaborate) way: If you lie on the bottom of a deep pool wearing scuba gear, you'll see the sun wobbling around, brightening and darkening, and changing

shapes, suggests University of California physicist Carl Gwinn. Thanks to water waves, it's twinkling! 

Do planets also twinkle? Not so much, because their larger disks of light "average out" the light bendings. Huge-disked Jupiter and Saturn twinkle not; smaller-disked Mercury twinkles a little.

Finally, to turn off all twinkling, ride up on the space shuttle beyond Earth's thick cloak of gases– a fine vantage point for looking through a telescope à la Hubble.

Q. How does the Coast Guard find people lost at sea?– J.P. Jones

A. First they interview the family or friends about the type of boat, its destination, and any survival gear on board, says oceanographer Arthur A. Allen in Scientific American magazine. Then they use software called the Search and Rescue Optimal Planning System (SAROPS) to simulate different drift trajectories– people, oil drums, life rafts, sea kayaks, sailboats, etc. 

"With SAROPS, we can make more than 10,000 guesses about where the boaters might end up" he says, and figure which is most probable.

SAROPS can also factor in the effect of winds on various currents; then, with projections in hand, the rescuers deploy helicopters, C-130 planes, boats called cutters and motor lifeboats to try to find the missing. It even factors in the effect of white caps on waves that decrease visibility. 

Given the ocean's vastness, it's like "looking for a soccer ball– a person's head above water– in an area the size of Connecticut," says Allen. Survival models will tell how much heat the person can tolerate losing either directly or from shivering. Here, being big and fat or muscular is helpful. Dehydration too can exacerbate hypothermia.

"Yet even if weather conditions would permit a search to continue," he adds, "it may be called off if the computer models say the victims have no chance of still being alive."

Q. What is "assortative mating," and how might it be feeding the obesity epidemic? –R. Barr

A. One aspect of the phrase refers to the tendency of people to marry others like themselves, all the way down to choosing those with body builds like their own as spouses and to have kids together, say Michael Power and Jay Schulkin in The Evolution of Obesity. 

Thus "big" people will tend to date and marry other "big" people, just as thins tend to pair up with other thins, even matching up on their arm and leg sizes. The effect is stronger today as body types have become evident at a younger age, by the dating teens and early twenties.

Statistically speaking, say the authors, the pairing off of similar-sized individuals will amount to a double dosing of similar genes passed on to offspring. This could help explain the existence of both obesity-prone and obesity-resistant individuals. Thus, in our culture, the genetics of assortative mating may be affecting the distribution of fat and lean people, and may, in theory, cause a doubling of obesity prevalence in a few generations.

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Send Strange questions to brothers Bill and Rich at strangetrue@cs.com.

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