Re: Missing term

[Brian Whatcott <betwys1@SBCGLOBAL.NET>]

At 09:44 PM 8/29/2003 -0400,  Chuck Britton, you wrote:

>         Passing from liquid to vapor at temp and pressure above the
> critical point show no demarcation in their properties. Are,
> therefore, liquids and vapors the same thing??????

I would say that above the critical point,  liquid and
gas are indistinguishable.

> >
> >
> >There seems to be quite a wide acceptance of the idea that
> >   solidified glass flows. This position is supported
> >by the assertion that medieval church glass is thicker at the foot.
> ///
> >The creep, if I can call it that, apparently takes place over very
> >   much longer time-scales, so the concept is not so clear cut.
>
>         If the creep is as fast as claimed - then we could run an
> easy optical interferometer experiment to measure it over available
> time frames.
> --
> Chuck Britton


The basis for the retreat from conceptualizing glass as a fluid is the
existence of clear cut interferometric results which do support the
position that creep in glass sufficient to produce the observed thickness
disparities does not occur in intervals measured in hundreds of years.

Though I do not have such results to hand, if I suppose a pane of glass
that is 400 years old varies from 1/4 to 1/3 inch, top to bottom,
I might test for a time rate of change of thickness of
7/24 inch > 1/3 inch per 400 yrs
or say 1 mm per 400 yr
1 um per 0.4 yr
150 nm (1/4 lambda) in 22 days

If I wanted to hurry the test along, I could well hang a load from
a glass strip in the optical path. 1/4 lambda path length reduction
 in a day or two would be achievable, if the fluid glass hypothesis
 held water. But it doesn't.


Brian Whatcott    Altus OK    Eureka!