Re: [Phys-l] States of matter?

[John Denker <jsd@av8n.com>]

On 10/13/2011 08:04 AM, David Bowman wrote:
> Not to mention spin glasses, nuclear matter and quark matter.  The
> electron-degenerate carbon/oxygen material in white dwarfs probably
> ought to be considered as its own distinct phase.

Now those are some fun examples.  What about a neutron star?
Or do you just consider that a really high-mass nucleus?

===================

While we are all pointing out ways in which "solid liquid gas"
might be too few categories, somebody ought to point out that
it might be too many:

Above the critical point, gas is indistinguishable from liquid.
The word  fluid  is used to describe this state.

Of course the words gas and liquid remain useful ... because
they /sometimes/ match reality.

This illustrates two points:
 -- I think that people should be allowed to define things
  however they like, according to their best judgment.
 -- On the other hand, definitions have consequences.  If
  you define things in a way that does not match reality,
  that counts as bad judgment.


On 10/13/2011 08:02 AM, Richard L. Bowman wrote:
> Chuck's comment, "I fear that they are mainly arguing as to what a
> correct Multiple Choice Test would include," seems to be the
> operative one for me. There have been too many occasions where I
> blame our elementary, middle and even high school educational systems
> for wanting only to label things so they can be memorized rather than
> emphasizing the models of how the universe works.
>
> So, to add to the list that others have already created, I'll mention
> the distinctions between mixtures and compounds that our children had
> to learn (and one of our sons now has to teach to middle school
> students) and the definition of mixtures as things that can be
> separated. So where do glasses fit into this scheme? And are neutrons
> mixtures of electrons and protons since under the right conditions
> one can separate electrons and protons from a neutron sample?

Wow.  +1 to that.

The one about "mixtures" is part of a package that also includes
requiring students to classify processes as "chemical change"
versus "physical change" based on casual macroscopic observations.
This is arrant nonsense, as detailed here:
  http://www.av8n.com/physics/chemical-physical.htm

Any student with one iota of critical thinking ability can see
that it is nonsense, and can see that the examples given in the
book do not conform to the definitions given in the book.

Typically the business about "chemical change versus physical change"
is heavily emphasized during the first week of class, along with
an emphasis on the poster version of "the scientific method"
  http://www.av8n.com/physics/scientific-methods.htm#sec-poster
and an emphasis on "significant figures"
  http://www.av8n.com/physics/uncertainty.htm

These three things are incompatible with science, and indeed 
incompatible with common sense ... /and the students know it/.

These three things serve to put everyone on notice that critical 
thinking is not tolerated in school.

To say the same thing in slightly more positive terms:  If you
want to improve students' critical thinking skills, stop requiring
them to learn stuff that cannot possibly be true.

I'm not saying this is easy, but it's got to be done.