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Environment & Science

Atmospheric and climate research is all about math and chaos

I'm almost done stuffing my brain with atmospheric research at NCAR, the National Center for Atmospheric Research in Boulder. We spent vast amounts of time discussing modeling for global climate change, which couples weather data with all kinds of other things: interactive ocean, land surface, and sea ice models; changes in greenhouse gases, solar input, volcanoes, visible air pollution; standard carbon cycles. If that sounds like math, it is. All week long, we've seen math, upon math, upon math. You can imagine, if you're doing a lot of calculations the way these people are, they love their supercomputers, which make it possible for answers to emerge in one's lifetime. Some of these scientists talk about signals, and patterns, and how both of those can create enough certainty that scientists can say with confidence what will happen. But they also acknowledge, quite correctly, every day, that the math part of their job has limitations. 

I really liked one talk talked a little about Pierre LaPlace. He was a French mathematician and philosopher. A quote of his, known as LaPlace's Demon, postulates the existence of One Equation to Rule Them All: a calculation that, in theory could be solved, to tell us what will happen, and what has happened in in the past. 

We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at any given moment knew all of the forces that animate nature and the mutual positions of the beings that compose it, if this intellect were vast enough to submit the data to analysis, could condense into a single formula the movement of the greatest bodies of the universe and that of the lightest atom; for such an intellect nothing could be uncertain and the future just like the past would be present before its eyes.

You could conceivably interpret LaPlace's Demon as the end of a field of study. I heard this idea, and remembered it from a play; it was stolen by a character, Thomasina, in the Tom Stoppard play Arcadia. ("If you could stop every atom in its position and direction, and if your mind could comprehend all the actions thus suspended, then if you were really, really good at algebra you could write the formula for all the future; and although nobody can be so clever to do it, the formula must exist just as if one could.") If LaPlace, and Stoppard's Thomasina, are right, the movements and fate of everything in the universe is a problem that is soon solvable, dependent only on the capabilities of supercomputer calculators. But, even though NCAR is about to open a new supercomputer in Wyoming that can crunch equations way, way, way faster than the current supercomputer, the NCAR scientists who rely on modeling in climate and atmospheric science see plenty of chaos in the system, still. That chaos comes from variables they're working to understand, better. 

Later in Arcadia, another character, Valentine, tries to explain statistical modeling and regression to a non-mathematician. 

Pictures of turbulence – growth – change – creation – it’s not a way of drawing an elephant, for God’s sake! The unpredictable and the predetermined unfold together to make everything the way it is. It’s how nature creates itself, on every scale, the snowflake and the snow- storm. It makes me so happy. To be at the beginning again, knowing almost nothing. People were talking about the end of physics. Relativity and quantum theory looked as if they were going to clean out the whole problem between them. A theory of everything. But they only explained the very big and the very small. The universe, the elementary particles. The ordinary-sized stuff which is our lives, the things people write poetry about – clouds – daffodils – waterfalls – and what happens in a cup of coffee when the cream goes in – these things are full of mystery, as mysterious to us as the heavens were to the Greeks. We’re better at predicting events at the edge of the galaxy or inside the nucleus of an atom than whether it’ll rain on auntie’s garden party three Sundays from now. Because the problem turns out to be different. We can’t even predict the next drip from a dripping tap when it gets irregular. Each drip sets up the conditions for the next, the smallest variation blows prediction apart, and the weather is unpredictable the same way, will always be unpredictable. The future is disorder. A door like this has cracked open five or six times since we got up on our hind legs. It’s the best possible time to be alive, when almost everything you thought you knew is wrong.

I kind of feel that way after my week here. Which is great, frankly.