Talk:Metastability/Archive 1

Archive 1

Dropped text

I dropped the following text during a merge:

Systems prone to metastable states tend to exhibit power law behavior when measured over time. This is because the interactions are scale invariant. For instance, adding a single grain to a sandpile can result in anything from a small local disturbance (common) to the collapse of almost the entire pile (rare).

I'm not sure this is correct, and it's unreferenced and rather sweeping in scope. References would be appreciated if this claim is defensible. -- Beland (talk) 01:40, 6 June 2008 (UTC)

Hello! I (wavepacket) added that text. I agree it is rather sweeping, but of course there is the usual author's tension between readable prose and mathematically precise terminology. I am not yet good at both at the same time. One reference might be Manfred Schroeder's "Fractals, Chaos, Power Laws" (1991, WH Freeman and Company). Chapter 4 (Power Laws: Endless Sources of Self-Similarity) notes that "scaling invariance results from the fact that homogeneous power laws lack natural scales...". In his references, Schroeder points to examples from RM May (Science 214 pg 1441), and a very cool power-law distribution of impact rates vs. particle size graph from Schoemaker, US Geological Survey.

Metastability vs hysteresis

I think that the article would gain from distinguishing between the words metastable equilibrium and hysteresis. A system at metastable equilibrium is well described by Statistical mechanics and the fluctuations obey the fluctuation dissipation theorem. On the other hand hysteresis refers to the fact that most physical systems do not reach equilibrium instantaneously.

EDIT: Perhaps it is better to write it the following way:

A metastable system can equilibrium system for all purposes. As an example the state of a metastable system is fully described by the value of temperature and pressure. (unsigned comment)

I added a "see also" link, but not an explanation of the difference between the two concepts. They both seem to have pretty clear definitions. If anyone feels the need to add this contrast, I would say it this way: hysteresis is the dependence of state on the history of the environment, not just the current environment (which may or may not imply equilibrium) and metastability is equilibrium (a stable state) outside the ground state. -- Beland (talk) 12:51, 6 June 2008 (UTC)

Created two subarticles

I created two subarticles in order to be able to distinguish and specialize them.--Carl Hewitt 04:43, 21 July 2005 (UTC)

Additional note: Physics page no longer explains metastable. (unsigned comment)

I've merged several articles back into this one, so that the general scientific concept could be explained, and then applied to the various fields. Some subarticles remain. -- Beland (talk) 12:52, 6 June 2008 (UTC)

Is this wrong?

"It is analogous to being balanced precisely at the top of a round hill, rather than safely at the bottom of a valley" - -Wouldn't that be a definition of unstable (i.e. a small disturbance moves the system further and further away from the initial point) rather than metastable? Commutator (talk) 07:45, 13 June 2008 (UTC)

Ferromagnetic materials

-Ferromagnetic materials also present a metastable behavior. If one considers the presence of an external magnetic field, the equilibrium state is obtained when the material aligns its magnetization with the exterior field. But if the sample already presents a residual magnetization, which is in the opposite direction of a small exterior field, then the system becomes metastable. This situation has a very good description, what makes it even more interesting. —Preceding unsigned comment added by 129.132.146.33 (talk) 11:05, 17 July 2008 (UTC)

Expert attention needed?

There's an expert attention needed tag in the article, but it's not particularly obvious why. (Obviously any Wikipedia article would be benefitted by having an expert view...) Unless someone suggests what specific issue should be looked at, I'll clear the tag. Djr32 (talk) 18:01, 1 August 2009 (UTC)

Done. Djr32 (talk) 20:54, 2 October 2009 (UTC)

Metastability in electronics

There's a separate article about metastability in electronics - should add a link from this section to the article —Preceding unsigned comment added by 132.68.244.59 (talk) 20:44, 15 February 2010 (UTC)