In Max Born's Optik, when he discusses the optics of metals, he has a table
of values of n and n\kappa for various metals. He remarks that n is often
less than 1, which implies that the speed of light in the metal is greater
than in a vacuum;

that the value of the dielectric constant computed
from these values is negative, which is meaningless;

and that some formulas
he established don't seem to be consistent with these values.

He explains
all of this. The issue of the speed of light he resolves by talking about
group velocity and by claiming that the instance of faster than light
travel doesn't count as a signal, which is the real issue. The issue of
the negative dielectric constant and the inconsistency with earlier theory
he deals with by referring to the discussion in Chapter I of difficulties even
in the case of nonconducting materials, where the issue is resolved by
considering the separate effects of electrons and nuclei in the material.

The corresponding section of Born and Wolf doesn't mention these difficulties.

Any idea why the interesting discussion was removed?

Also, both books refer to a paper of A.Kundt from the late 19th century
which directly measured the dielectric constants of metals by making
extremely thin metal prisms. Any idea where one might find this article
online? Has this work been reproduced by any modern research? These days
they might have better ways of setting up the same experiment.

In Max Born's Optik, when he discusses the optics of metals, he has a
table
of values of n and n\kappa for various metals. He remarks that n is often
less than 1, which implies that the speed of light in the metal is
greater
than in a vacuum;

Also, both books refer to a paper of A.Kundt from the late 19th century
which directly measured the dielectric constants of metals by making
extremely thin metal prisms. Any idea where one might find this article
online? Has this work been reproduced by any modern research? These days
they might have better ways of setting up the same experiment.

Nowadays n and k measurements are usually done by looking at the
reflectance vs angle.

Nowadays n and k measurements are usually done by looking at the
reflectance vs angle.

And what? Ellipsometry at various agles I suppose?



So I believe. I get my data out of Palik & Ghosh.

"Phil Hobbs" wrote > Allan Adler wrote:
In Max Born's Optik, when he discusses the optics of metals, he has a
table
of values of n and n\kappa for various metals. He remarks that n is often
less than 1, which implies that the speed of light in the metal is
greater
than in a vacuum;

snip, admirable answer by PCDH (as usual), sorry.

Also, both books refer to a paper of A.Kundt from the late 19th century
which directly measured the dielectric constants of metals by making
extremely thin metal prisms. Any idea where one might find this article
online? Has this work been reproduced by any modern research? These days
they might have better ways of setting up the same experiment.

http://en.wikipedia.org/wiki/August_Kundt

Have you tried Google Books (Full View Option)?
I have found amazing stuff there.
There are many answers concerning (August) Kundt.
I do not have the courage to sift through them.
I thought of him thus far as an acoustician but apparently he worked in
optics as well.

Nowadays n and k measurements are usually done by looking at the
reflectance vs angle.

And what? Ellipsometry at various agles I suppose?

Have you tried Google Books (Full View Option)?
I have found amazing stuff there.
There are many answers concerning (August) Kundt.
I do not have the courage to sift through them.
I thought of him thus far as an acoustician but apparently he worked in
optics as well.

I haven't learned to use Google Books. Also, I have a lot of problems with
my ancient browser. I'll see what I can find out next time I use a more
contemporary computer and browser.

As to B & W, Emil Wolf is still around at the University of Rochester,
most likely emeritus, so maybe you can get in touch with him and ask.

BTW where did you find your copy of Born?

BTW where did you find your copy of Born?

Germany. You might be able to order it from www.amazon.de.
I bought mine about 25 years ago. At the time, and maybe still,
they had a very good book distribution system. I walked into a
bookstore in a small town and asked about the book and they told
me they would have it the next day.

I put off reading it for decades because I thought I didn't have time
to get involved in its details. So, recently, I conned myself into reading
it by telling myself it was just to practice my German. I'm not checking
all details but I am nevertheless following it without much effort. One
advantage of reading it in German, apart from being able to get Born's
point of view by itself (he is a very good writer), is that I cannot avoid
reading it slowly; that is something I often don't have the patience
to do in English.

Knowing German is a formidable advantage if one wants to study "early
physics", mostly 19th century and early 20th.

I forgot to mention that if you want to download stuff from Google Books
in a library you need at the minimum a CD.
These downloads are typically 20 MB sometimes more, sometimes less.
I assume that your computer can read CDs.

I haven't learned to use Google Books. Also, I have a lot of problems with
my ancient browser. I'll see what I can find out next time I use a more
contemporary computer and browser.