Re: [asa] Bacterial Gene May Affect Climate And Weather

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Date: Sat Feb 17 2007 - 22:03:21 EST

AFPhys says:

> By the way, I work intimately with supercomputer modeling and the results
> of such computations. Believe me when I say that even very well understood
> physical models are subject to huge errors when it comes to comparison of the
> outputs of these runs with real world data and inputs. We're often stymied as
> to what is going on because our models didn't suggest things we actually see
> in or simple, well measured, lab situations.

It is one thing to emphasize that there are limitations. Anyone
involved with computer modeling understands that. It is
another thing to say "give up".

As you say, also, there is a great problem with "dynamics". The "mesh" that
the present models are using is ridiculously large (by necessity) and there is
no foreseeable computational technique or equipment on the horizon to overcome

If we follow this logic, then we should have listened to
"give up" with the Sommerfeld model of a free electron gas.
It's a silly model when you think about it. It ignores electron-
electron interactions in a _metal_ (an inherently chaotic system
and surely one that contains a multitude of electrons).
How worse could you get than such a stupid idea? Well, if we
had listened to "give up", we would not have improved this model
to handle semiconductors, and we would probably still be using
an abacus or a slide rule.

The Boltzmann model for an ideal gas is just as stupid. Should
we have listened to "give up" on statistical mechanics too? Then
we would never have arrived at even the Sommerfeld model.

Maybe we should "give up" on particle physics. We hardly have
an easy way to model the entire standard model quantitatively.
Perhaps we have given up on it in the US.

Resolution is an important issue. At some level of resolution,
we can probably expect chaos, but, just like the challenges
of semiconductors, gas laws, and particle physics, we start
with the large grid and gradually work our way to the details.

by Grace we proceed,

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Received on Sat Feb 17 22:03:49 2007

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