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Science File | Mind Over Matter

The Good, the Bad and the Context

September 04, 1997|K.C. COLE | TIMES SCIENCE WRITER

In a high school science class recently, I gave the students some of my own articles from the Los Angeles Times to read as examples of science writing.

"Wow," said one of the students. "Your writing is really bad!"

It took me a while to realize it was a compliment. "Bad" was teenage for "good."

As always, context is everything.

In fact, one of the reasons that the discovery of zero produced such a profound revolution in mathematics is that zero allows you to put numbers in their place. The numeral 1 in the number 1,000,000 means something very different from the same numeral in the number 10 or 1,001.

In the same way, June marks the beginning of summer--if you happen to be in Los Angeles. In Buenos Aires, the same month marks the beginning of winter. The number 911 means "emergency." But in another context, mathematician Ian Stewart points out, the same number could mean that you lost the lottery, or that you live on a long street.

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Just as you may not recognize your dentist in the supermarket checkout line, scientists often have to strain to recognize scientific data out of context. The researchers looking at images of Mars through their camera on Pathfinder got a big surprise when the camera uncoiled to its full height, and suddenly the boulders looked smaller. The observers didn't have any context to judge the scale of the first images correctly.

With only one-third the gravity of Earth, geological forces on Mars also have to be seen in a very different context. Weaker gravity means that mountains on Mars can be much higher than mountains on Earth, because gravity doesn't so readily pull them down. Canyons can be deeper, because the walls don't so readily cave in.

The relief on Mars gets as high as 20 miles. "There's nothing like that on Earth," said Pathfinder project scientist Matthew Golombek.

Mountains on Mars can also get higher because the geological context is different. Earth's continents slide about on enormous plates that float around on "a mushy mantel," Golombek said. Mars' terra is firmer. So tall mountains have more support.

Water also flows differently in one-third gravity--which affects the way it eats away at rocks, tumbles and scours the landscape. When geologists try to reconstruct the biblical-scale floods that scarred the Martian landscape billions of years ago, they'll have to take this different context into account.

Indeed, everything flows differently, depending on gravitational context. In zero gravity--for example, on the space shuttle--water doesn't flow at all but floats in spherical blobs. Even flames--which are burning gases--tend to form into spheres.

Some things even change their identity depending on their context. A cake crumb on the floor is dirt; the same crumb on the cake is food.

Other things change shape: The Earth is round over a long distance. But a small patch of Earth is flat.

Still others become invisible. Where do the stars spend their days? Up in the sky, but you can't see them in the context of a bright sky.

Gravity completely disappears in the context of falling. Indeed, some physicists dismiss gravity as a "pseudo force" because it doesn't exist for something that's falling. That's why astronauts "float" in orbit around the Earth. Gravity hasn't gone away. Instead, the spaceship circles in a continual state of free fall, pulled toward Earth enough to keep it in orbit, but not enough to send it crashing to the ground.

Luckily for scientists, not everything morphs chameleon-like because of context. A basic rock such as basalt is basalt wherever it's found. "I could not tell you," says Golombek, "whether it's from Mars or the moon or the ocean bottom."

Context plays its part in what happens to the rock. Moon rocks do not get chemically broken down by air and water, or cooked by heating in volcanoes. All these things leave their fingerprints--telling geologists exactly where the basalt has been. Scientists create confusion of their own when they use their in-house jargon out of context. You'll often hear a researcher describe a result as "robust," but that doesn't mean it's big or heavy or strong; instead, it means the measurement has stood up to many tests. A result described as "non-trivial" is important or even profound.

Or perhaps "bad" would be a better word in this context.

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