Monday, April 4, 2011

Messy Science

The type of science I like is what I call 'messy science'.  'Neat science' is the sort where you are looking at only one or maybe a few (easily counted) objects, which can be described by one or only a few number, like mass and momentum.  Celestial mechanics is a 'neat science' in this way, at least for the solar system.  Also, I hope, obvious is that being neat does not mean that it's easy.

Messy science is things like organismal biology or, for my own professional work, climate.  In climate, you can take something simple, like the rotation of the earth, and wind up with a lengthy list of things which affect it.  Conversely, you have a long list of things affected by it -- including the climate.  In What is a Day?, I mentioned a few things which affect the earth's rotation.

Another thing that is involved is the fact that the earth's inner core -- sitting about 5000 km below us -- rotates at a different rate than the crust.  In between the two is the liquid outer core, which has its own angular momentum, and whose top is about 3000 km below us.  More recent work (that paper was published in 2000) is now suggesting that one can learn about climate by studying the earth's core's rotation -- here for the press release, or here for the Dickey, Marcus, and deViron, 2011 paper: Air Temperature and Anthropogenic Forcing: Insights from the Solid Earth.

What a lovely, messy, situation!  We can look to the earth's core for signs about what is happening in climate!

I'll come back to this later for a discussion of the research paper itself.  Maybe, like many new ideas, it won't hold up.  If not, somebody else will get to write the paper which shows why not.  In the mean time, here's another candidate for the messiness of climate.  There's also another datum for how small the scientific community is.  I've met the lead author; it was she who explained to me how it was possible to measure length of day variations to such very high precision.

2 comments:

EliRabett said...

Not sure about celestial mechanics, it is the ultimate n body problem with a lot of chaotic detail in that clockwork orange

Penguindreams said...

That's what I mean about the difference between messy and not simple. Celestial mechanics is certainly not simple. But it also certainly is not as messy as climate. Number of degrees of freedom for celestial mechanics is only 6N, and N is not terribly large for the solar system. So you're looking at only dozens to hundreds of degrees of freedom. For climate, there doesn't seem to be any good, hard figures, but the climate models have millions of degrees of freedom.