chaosbook:diffusion:nigel

** Predrag to Nigel**:
I've been barking up every tree for years, but this is the first time that a light went on upstairs, thanks! The questions are good, so sorry for the delay, but I used them to rewrite a section in the intro to ChaosBook: please have a look at

which, read in tandem with

hopefully addresses your remark? Let me know what to edit next…

— *Predrag Cvitanovic 2009-01-12 04:30*

**Nigel to Predrag:**
you didn't tell me the most amazing thing that I just learned about from your chaos book. I refer to
the passage in chapter on Deterministic diffusion (see ChaosBook.org/chapters/diffusion.pdf):

Chaos: what is it good for? TRANSPORT! Measurable predictions:

- AFM tip drag force figure 24.7 c).

That Smale’s “structural stability” conjecture turned out to be wrong is not a bane of chaotic dynamics - it is actually a virtue, perhaps the most dramatic experimentally measurable prediction of chaotic dynamics. As long as microscopic periodicity is exact, the prediction is counterintuitive for a physicist - transport coefficients are not smooth functions of system parameters, rather they are nonmonotonic, nowhere differentiable functions.

This is totally bizarre. Transport coefficients are averaged quantities, at least as thought about from kinetic theory or Green-Kubo formulae. So this Weierstrass-like behavior is astonishing. How could you resist telling me about it??!! I got the hint about this from Greg Eyink, who I was talking about last week in Cambridge.

Now my question: do you know an explanation that a simple-minded physicist like me could understand? And another question: how could I see this in experiment? Has it been seen in simulation? etc….

— *Nigel Goldenfeld, nigel [snail] uiuc.edu, 2008-12-20 12:25 *

chaosbook/diffusion/nigel.txt · Last modified: 2010/02/02 07:55 (external edit)