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Thursday, January 16, 2014

Does Scale Matter?

Mathematicians have devised a new way to fly:

When the Wright brothers pioneered powered flight, said Leif Ristroph, they “didn’t solve a lift problem; they solved a stability problem.”

Dr. Ristroph, who works in applied mathematics at New York University’s Courant Institute, also solved a stability problem recently, with a small, hovering, flapping-wing flying machine that looks for all the world like a flying jellyfish.

The lightweight, electrically powered machine, which seems to be the first of its kind, keeps itself right side up without the benefit of sensors or any righting mechanism. Its stability is completely a result of its shape and the movement of its three-inch wings.


As to the problem of stability, Dr. Ristroph said they solved it from an engineering perspective, but the math is still not settled. “We don’t really understand for the active flyers how this works,”

UN Says Lag in Confronting Climate Woes Will be Costly:

Nations have so dragged their feet in battling climate change that the situation has grown critical and the risk of severe economic disruption is rising, according to a draft United Nations report. Another 15 years of failure to limit carbon emissions could make the problem virtually impossible to solve with current technologies, experts found.

The flying jellyfish's stability is very difficult to understand because non-laminar airflow is chaotic. Modeling chaotic systems is extremely difficult, even when trying to understand something as simple as stability for something small and eminently observable.

Yet climate scientists claim certainty for their models, which involve a chaotic system that is large and, in many respects, very difficult to observe.


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