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Butterfly Effect


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Butterfly Effect, illustration

Credit: Andrij Borys Associates / Shutterstock

Lily's eyes scanned the yard, an expansive tract of suburban real estate she called the back 40. She was not pleased.

"Eliot, this is embarrassing. Our property makes the Dust Bowl look lush. Is it ever going to rain again?"

Her husband turned toward the sky as if seeking an answer. But of course he already knew what his response would be, and so did she.

"October, Lily ... It rains in October."

"I don't care about seasonal behavior or what's normal for the state. If it doesn't rain in Longmont or Loveland, well, tough for them. I just care about this backyard patch. Make it rain here, will you? You're the meteorologist."

"Yes, dear, I am," Eliot replied, flashing a slight smile in the interests of domestic tranquility, and went inside.

Despite the fact that Eliot had a sheepskin testifying to his meteorological chops Lily's gibe was a reminder he wasn't the man he had once hoped to be. He wasn't really a weather forecaster. In high school, he could look at the clouds, sense the temperature, and know a front was moving in. Some of his friends admired his ability to predict afternoon thunderstorms, while others thought he was just obsessive. Eliot didn't care much. He enjoyed the fact that his skills could be tested every day, his predictions verified or disproved within hours. It was like being a day trader, but without the risk.

Eliot followed his meteorological interests through grad school, but by the late 2030s technology was rendering his skills obsolete. Weather forecasts were increasingly the province of computer models, massive calculations that spit out accurate predictions for any place on the planet, down to an acre or less. This development was inevitable, requiring only the ability to build a finer grid of weather datawind, temperature, barometric pressureand the compute power to crunch it all. Both were now at hand.

Improved satellites had refined the grid by a factor of 20 in all directions. The whole planetcontinents, ocean surface, the entire atmosphere below six mileswas now sampled on a scale of 300 feet. Every few minutes, the weather was measured and binned into five trillion cells, the mother of all spreadsheets.

It was Eliot's job to feed this vast anthill of numbers into the models several times a day and bring to bear the compute power available in the Extended Cloud. Yes, he had to understand what he was doing, and, yes, he had to be careful. But it wasn't traditional weather forecasting, and definitely not weather manipulation.

So Lily's remarks bothered him. Was he truly helpless? All his life people had teased him with Charles Dudley Warner's bromide that everyone complains about the weather, but no one does anything about it. But he was a scientist. He knew that weather involved immense highly energetic systems. The output of 100 power plants was nothing compared to a hurricane's terawatts. How could anyone do anything about the weather? It was akin to moving the Rocky Mountains.

He also knew the weather was a system that was chaotic and close to equilibrium. A small change could have big consequences. The butterfly effect.

The idea that a butterfly could precipitate a storm was a popular idea, recognized centuries ago. Eliot had thought about it in school but reckoned the flapping wings of a single insect really couldn't do much. And predicting its effects was impossible.

But now he considered a slightly greater perturbationnot a butterfly's flutter but a disturbance as large as a tennis court. A change in the parameters of one cell in that mother of all spreadsheets. Could such a perturbation have a significant effect anywhere else?

Eliot decided on an experiment. First, he ran a model based on the latest grid datanothing new therepredicting the weather 20 minutes into the future. Then he went back into the input matrices and manipulated the parameters in one cell, the one that covered his backyard. He then lowered the temperature by five degrees and ran the model again.

A simple program subtracted the two results, color-coding any differences. Blue indicated cells with no change, green very slight differences, and yellow and red locations that were significantly altered. Because weather, carried by the wind, doesn't move faster than the speed of sound, he looked at the results only within 250 miles. Beyond that, Eliot would need a prediction further into the future, and couldn't be sure if any effects were due to his manipulated data or not.

The difference plot was mostly just a noisy sea of blue and green pixels. A few were red, indicating, for example, the barometric pressure was 1% greater or lesser than it would have been without the backyard temperature change. His theoretical butterfly hadn't had much effect. But there was one spot that was yellow ... where the local wind speed had increased by a factor of two. A factor of two! Eliot pushed back his chair and let out a low whistle.

Lily watched her husband inch the rented pickup down the driveway, stopping just short of the desiccated wasteland that was their yard. He had lined its bed with plastic and spent several hours filling it with water from the kitchen sink.

"Are you going to tell me what this is about, Eliot? I mean, is this your idea of making rain?"

"I'm going for a real live butterfly effect."

"Like when you feel nervous? When your tummy turns upside down?"

"Not at all. It's when a small stimulus produces a big effect. Consequences that greatly outweigh causes."


But there was one spot that was yellow ... where the local wind speed had increased by a factor of two. A factor of two!


"You mean like the shooting of Archduke Franz Ferdinand?"

"Who?"

"1914. Franz Ferdinand was assassinated by a fervent Yugoslavian nationalist. Small event. But within months, they were digging trenches in France. The First World War.

"No trenches here, Lily. And no archdukes either." He pulled the gate on the pickup, and three tons of water spilled out onto the parched earth.

In 20 minutes, Eliot was looking at his difference plots. Despite the fact that he had lowered the surface temperature of his yard considerably more than the five degrees of his numerical test, there was still no apparent effect within 250 miles. This butterfly had flapped its wings for naught.

What Eliot couldn't see, and wouldn't understand until much later, was that six hours after he flooded the yard, a Russian military transport carrying diplomats would run into trouble on its approach to Warsaw's Bemowo Airfield. The flight forecast had predicted smooth skies all the way. And they were, except at 3,000 feet short of the runway where an unusually forceful dust devil lifted one wing and tossed the plane on its back.

Was it an accident? The Russians certainly didn't think so. This was subtle sabotage, and no degree of pleading could convince them otherwise. In the predawn skies the following day, an unmanned drone headed west, hugging the flat landscapes of Northern Europe. Someone had finally done something about the weather.

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Author

Seth Shostak (seth@seti.org) is the senior astronomer at the SETI Institute in Mountain View, CA.


©2017 ACM  0001-0782/17/11

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