| Topic: |
Science > Physics |
| User: |
"Damir Zucic" |
| Date: |
22 Dec 2004 06:24:49 AM |
| Object: |
Physics Essays - weird journal? |
Hi everybody,
I am curious about the journal "Physics Essays". What kind of journal is
that? An electrical engineer from Croatia, which used to work in a big
industrial company and later founded a small private company dealing with
industrial automatics, elevators and such things (www.drives.hr, the text
is in Croatian language), managed to publish two "fundamental" articles
in this journal.
==========================================================================
By publishing such articles, the "Physics Essays" journal is endangering
Croatian universities. Even a rather decent local newspaper "Vjesnik" (in
Croatian language,
http://www.vjesnik.com/html/2003/12/07/Clanak.asp?r=sss&c=7 ) described
the first article as significant scientific contribution and states that
"it was published in renowned scientific journal".
Such references (together with some other doubtful contributions)
may be legally used to obtain a university position at some technical
faculty in Croatia and probably in some other developing countries!
==========================================================================
These two articles, "Quantization in Classical Electrodynamics"
(vol. 15, number 1 (2002), p 41) and "Absorption and Emission of Radiation
by an Atomic Ascillator" (vol. 16, number 2 (2003), p. 162) try to explain
some quantum phenomena by pure classical electrodynamics.
It is quite hard to read these two articles, but I have found some weird
things there. Here is just a short selection:
(1) It is assumed, that the total radiation of an electron in the atom is
the sum of the radiations of two dipoles, which are put perpendicular
to each other. What forms two dipoles in a hydrogen atom?
This thesis is derived from the book written by Eduard Schpolski.
Anyone ever heard who was Eduard Schpolski and what was his contribution
to physics?
(2) Some other key references are bad books, written by incompetent authors.
The references are an interesting mixture of classic works by reliable
authors and very obscure texts. I know that three cited authors from
Croatia during their entire carrier have not published even a single
internationaly relevant work. ISI Web of Science easily proves
what I am saying. The same may be proven for some other cited authors.
(3) It is very difficult to understand what forms the hardware of a
transmission line in an atom. The transmission line model is used to
derive some important equations (!?).
(4) There is a consistent mixing of macroscopic equations and microscopic
phenomena. Why reviewers accepted that "... similar to the macroscopic
area, there is also a displacement current in the microscopic area
generated by the circular motion of an electron ..."?
(5) Some equations are derived by considering a simple LC circuit. Why
anyone should believe that these equations have anything to do with
an atom?
For decades, physics is being raped at most technical faculties in Croatia.
I used to work at the Faculty of Electrical Engineering in Osijek and I
remember that it was very hard to save three decent physics courses,
including introductory quantum physics. My coleagues in Zagreb, Split and
Rijeka were defeated - my physics courses are the only survivors and the
Faculty of Electrical Engineering is still the only technical faculty in
Croatia where students learn decent physics.
Some years ago, I was under heavy pressure by the reviewers of the complete
faculty curriculum, because I have insisted that our courses should be
compatible with the courses at the best universities in Europe and USA.
I have moved to the School of medicine so I expect that soon a new attack
will be launched against physics and my coleagues at the Faculty of
Electrical Engineering.
Any information about Physics Essays will be appreciated. I think that
such journals may be dangerous for universities in developing countries.
Damir Zucic,
http://garlic.mefos.hr/zucic
.
|
|
| User: "Franz Heymann" |
|
| Title: Re: Physics Essays - weird journal? |
22 Dec 2004 04:43:39 PM |
|
|
"Damir Zucic" <zucic@garlic.mefos.hr> wrote in message
news:cqbp2h$dkg$1@bagan.srce.hr...
[snip]
These two articles, "Quantization in Classical Electrodynamics"
(vol. 15, number 1 (2002), p 41) and "Absorption and Emission of
Radiation
by an Atomic Ascillator" (vol. 16, number 2 (2003), p. 162) try to
explain
some quantum phenomena by pure classical electrodynamics.
Every now and again some electrical engineer who may well be
thoroughly knowledgeable about classical electromagnetism makes a song
and dance about explaining the stability of the hydrogen atom by using
classical electrodynamics only. All such attempts always fail without
exception. Here is the reason, which is universally applicable to
showing the futility of such attempts:
Atomic physics as developed with the aid of quantum theory is riddled
with formulae containing Planck's constant h. This constant does not
appear anywhere in classical electrodynamics. It follows that the
writer is pulling the wool over the eyes of his readers.
Franz
[snip]
Franz
.
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|
| User: "Timo Nieminen" |
|
| Title: Re: Physics Essays - weird journal? |
22 Dec 2004 05:19:04 PM |
|
|
On Wed, 22 Dec 2004, Franz Heymann wrote:
Every now and again some electrical engineer who may well be
thoroughly knowledgeable about classical electromagnetism makes a song
and dance about explaining the stability of the hydrogen atom by using
classical electrodynamics only. All such attempts always fail without
exception. Here is the reason, which is universally applicable to
showing the futility of such attempts:
Atomic physics as developed with the aid of quantum theory is riddled
with formulae containing Planck's constant h. This constant does not
appear anywhere in classical electrodynamics. It follows that the
writer is pulling the wool over the eyes of his readers.
It can be conjured up out of classical electrodynamics. One need only take
the ratio of angular momentum flux density to intensity/(angular
frequency), or AM flux to power/(angular frequency) for a circularly
polarised plane wave or paraxial Gaussian beam, or for even more fun, a
paraxial Laguerre-Gauss beam.
Of course, using intensity/(angular frequency) is a sneaky way of saying
"let there be photons of energy hbar*omega".
--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
.
|
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| User: "Franz Heymann" |
|
| Title: Re: Physics Essays - weird journal? |
23 Dec 2004 12:50:27 AM |
|
|
"Timo Nieminen" <timo@physics.uq.edu.au> wrote in message
news:Pine.LNX.4.50.0412230913430.10549-100000@localhost...
On Wed, 22 Dec 2004, Franz Heymann wrote:
Every now and again some electrical engineer who may well be
thoroughly knowledgeable about classical electromagnetism makes a
song
and dance about explaining the stability of the hydrogen atom by
using
classical electrodynamics only. All such attempts always fail
without
exception. Here is the reason, which is universally applicable to
showing the futility of such attempts:
Atomic physics as developed with the aid of quantum theory is
riddled
with formulae containing Planck's constant h. This constant does
not
appear anywhere in classical electrodynamics. It follows that the
writer is pulling the wool over the eyes of his readers.
It can be conjured up out of classical electrodynamics. One need
only take
the ratio of angular momentum flux density to intensity/(angular
frequency), or AM flux to power/(angular frequency) for a circularly
polarised plane wave or paraxial Gaussian beam, or for even more
fun, a
paraxial Laguerre-Gauss beam.
Of course, using intensity/(angular frequency) is a sneaky way of
saying
"let there be photons of energy hbar*omega".
Timo,
You are usually very lucid, but I fear this last contribution of yours
is totally lost on me.
Franz
.
|
|
|
| User: "Timo Nieminen" |
|
| Title: Re: Physics Essays - weird journal? |
23 Dec 2004 01:08:18 AM |
|
|
On Thu, 23 Dec 2004, Franz Heymann wrote:
"Timo Nieminen" <timo@physics.uq.edu.au> wrote:
On Wed, 22 Dec 2004, Franz Heymann wrote:
Atomic physics as developed with the aid of quantum theory is
riddled
with formulae containing Planck's constant h. This constant does
not
appear anywhere in classical electrodynamics.
It can be conjured up out of classical electrodynamics. One need
only take
the ratio of angular momentum flux density to intensity/(angular
frequency), or AM flux to power/(angular frequency) for a circularly
polarised plane wave or paraxial Gaussian beam, or for even more
fun, a
paraxial Laguerre-Gauss beam.
Of course, using intensity/(angular frequency) is a sneaky way of
saying
"let there be photons of energy hbar*omega".
Timo,
You are usually very lucid, but I fear this last contribution of yours
is totally lost on me.
On re-reading, it's lost on me, too. What I meant to say was that, for
example, for a left circularly polarised plane wave,
quantum angular momentum: hbar per photon
classical AM flux: I/w
so one should be able to extract hbar by some suitable ratio. Of course, I
was mistaken, as all that one can extract is that the classical field is
spin 1.
--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
.
|
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| User: "Franz Heymann" |
|
| Title: Re: Physics Essays - weird journal? |
23 Dec 2004 09:31:07 AM |
|
|
"Timo Nieminen" <timo@physics.uq.edu.au> wrote in message
news:Pine.LNX.4.50.0412231658380.3984-100000@localhost...
On Thu, 23 Dec 2004, Franz Heymann wrote:
"Timo Nieminen" <timo@physics.uq.edu.au> wrote:
On Wed, 22 Dec 2004, Franz Heymann wrote:
Atomic physics as developed with the aid of quantum theory is
riddled
with formulae containing Planck's constant h. This constant
does
not
appear anywhere in classical electrodynamics.
It can be conjured up out of classical electrodynamics. One need
only take
the ratio of angular momentum flux density to intensity/(angular
frequency), or AM flux to power/(angular frequency) for a
circularly
polarised plane wave or paraxial Gaussian beam, or for even more
fun, a
paraxial Laguerre-Gauss beam.
Of course, using intensity/(angular frequency) is a sneaky way
of
saying
"let there be photons of energy hbar*omega".
Timo,
You are usually very lucid, but I fear this last contribution of
yours
is totally lost on me.
On re-reading, it's lost on me, too. What I meant to say was that,
for
example, for a left circularly polarised plane wave,
quantum angular momentum: hbar per photon
classical AM flux: I/w
so one should be able to extract hbar by some suitable ratio. Of
course, I
was mistaken, as all that one can extract is that the classical
field is
spin 1.
Quite.
I know of no collection of classical physical constants which can be
combined to give a quantity which has the dimensions of an angular
momentum and the magnitude of Planck's constant.
Franz
.
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| User: "John C. Polasek" |
|
| Title: Re: Physics Essays - weird journal? |
30 Dec 2004 09:09:02 AM |
|
|
On Thu, 23 Dec 2004 15:31:07 +0000 (UTC), "Franz Heymann"
<notfranz.heymann@btopenworld.com> wrote:
"Timo Nieminen" <timo@physics.uq.edu.au> wrote in message
news:Pine.LNX.4.50.0412231658380.3984-100000@localhost...
On Thu, 23 Dec 2004, Franz Heymann wrote:
"Timo Nieminen" <timo@physics.uq.edu.au> wrote:
On Wed, 22 Dec 2004, Franz Heymann wrote:
Atomic physics as developed with the aid of quantum theory is
riddled
with formulae containing Planck's constant h. This constant
does
not
appear anywhere in classical electrodynamics.
It can be conjured up out of classical electrodynamics. One need
only take
the ratio of angular momentum flux density to intensity/(angular
frequency), or AM flux to power/(angular frequency) for a
circularly
polarised plane wave or paraxial Gaussian beam, or for even more
fun, a
paraxial Laguerre-Gauss beam.
Of course, using intensity/(angular frequency) is a sneaky way
of
saying
"let there be photons of energy hbar*omega".
Timo,
You are usually very lucid, but I fear this last contribution of
yours
is totally lost on me.
On re-reading, it's lost on me, too. What I meant to say was that,
for
example, for a left circularly polarised plane wave,
quantum angular momentum: hbar per photon
classical AM flux: I/w
so one should be able to extract hbar by some suitable ratio. Of
course, I
was mistaken, as all that one can extract is that the classical
field is
spin 1.
Quite.
I know of no collection of classical physical constants which can be
combined to give a quantity which has the dimensions of an angular
momentum and the magnitude of Planck's constant.
Franz
That's because you haven't read my Dual Space theory. There I
developed a new fundamental constant, call it L, (for lack of
greeking on this teletype):
L = 1.771e-14m
from which
h = L*me*c/alpha
and you're right, it took one more fundamental constant.
Mr. Dualspace
If you have something to say, write an equation.
If you have nothing to say, write an essay
.
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| User: "Timo Nieminen" |
|
| Title: Re: Physics Essays - weird journal? |
23 Dec 2004 06:23:06 PM |
|
|
On Thu, 23 Dec 2004, Franz Heymann wrote:
Quite.
To change the topic, are you familiar with E. J. Post, "Formal structure
of electromagnetics"? If so, what do you think of the book?
--
Timo Nieminen - Home page: http://www.physics.uq.edu.au/people/nieminen/
Shrine to Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
.
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| User: "Franz Heymann" |
|
| Title: Re: Physics Essays - weird journal? |
28 Dec 2004 03:53:24 PM |
|
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"Timo Nieminen" <timo@physics.uq.edu.au> wrote in message
news:Pine.LNX.4.50.0412241021380.10522-100000@localhost...
On Thu, 23 Dec 2004, Franz Heymann wrote:
Quite.
To change the topic, are you familiar with E. J. Post, "Formal
structure
of electromagnetics"? If so, what do you think of the book?
No. When was it published?
I stopped buying books when I began to realise that senility is
lurking around the corner.
Franz
.
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| User: "TimoAllan NIEMINEN" |
|
| Title: Re: Physics Essays - weird journal? |
29 Dec 2004 12:20:05 AM |
|
|
On Tue, 28 Dec 2004, Franz Heymann wrote:
"Timo Nieminen" <timo@physics.uq.edu.au> wrote:
To change the topic, are you familiar with E. J. Post, "Formal
structure
of electromagnetics"? If so, what do you think of the book?
No. When was it published?
I stopped buying books when I began to realise that senility is
lurking around the corner.
1962, North-Holland. There's a Dover reprint also.
I've been having fun reading it while commuting. A skinny little book.
Apart from being interested in your general impressions, Post is very
pro-SI. I was wondering what a member of the anti-SI old
guard would say. The other fun thing is he uses (t,x,y,z) as
4-coordinates, so not the usual metric tensor.
--
Timo
.
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| User: "Franz Heymann" |
|
| Title: Re: Physics Essays - weird journal? |
29 Dec 2004 04:08:21 AM |
|
|
"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote in message
news:Pine.OSF.4.58.0412291607260.20735@dingo.cc.uq.edu.au...
On Tue, 28 Dec 2004, Franz Heymann wrote:
"Timo Nieminen" <timo@physics.uq.edu.au> wrote:
To change the topic, are you familiar with E. J. Post, "Formal
structure
of electromagnetics"? If so, what do you think of the book?
No. When was it published?
I stopped buying books when I began to realise that senility is
lurking around the corner.
1962, North-Holland. There's a Dover reprint also.
I've been having fun reading it while commuting. A skinny little
book.
Apart from being interested in your general impressions, Post is
very
pro-SI. I was wondering what a member of the anti-SI old
guard would say.
You know well what I think of SI, so I won't be responsible for
opening that can of worms yet again.
{:-))
The other fun thing is he uses (t,x,y,z) as
4-coordinates, so not the usual metric tensor.
I hope he does use coefficients -1,1,1,1
I used to use the Minkowski metric in my teaching days, with ict for
the fourth component of the position vector.
I will try and lay my hands on a copy of the book.
Franz
.
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| User: "TimoAllan NIEMINEN" |
|
| Title: Re: Physics Essays - weird journal? |
29 Dec 2004 02:45:11 PM |
|
|
On Wed, 29 Dec 2004, Franz Heymann wrote:
"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote:
Apart from being interested in your general impressions, Post is
very
pro-SI. I was wondering what a member of the anti-SI old
guard would say.
You know well what I think of SI, so I won't be responsible for
opening that can of worms yet again.
{:-))
Your SI tirades make for interesting reading, at any rate. Me, I use SI, I
teach SI. Perhaps this results from the trauma of doing a PhD in
astrophysics (being the last refuge of the anti-SI outside of fields where
it actually makes sense to not use SI).
The other fun thing is he uses (t,x,y,z) as
4-coordinates, so not the usual metric tensor.
I hope he does use coefficients -1,1,1,1
If you mean signs -+++, I forget, and left the book at work for the
holidays, so can't check for a while.
Post's point is (I think) that c being a fundamental property of
space-time, the metric tensor is its proper home, rather than hiding it in
the coordinates, or worse, choosing units with c = 1 in order to hide it
as completely as possible.
I used to use the Minkowski metric in my teaching days, with ict for
the fourth component of the position vector.
Ack! Complex coordinates to maintain maximal Euclideanness!
I started teaching relativity with only a fuzzy recollection of what I'd
done as a student half a lifetime ago. Teaching is the true way to learn
something well. I (so far) follow Jackson and use (iirc) +1,-1,-1,-1.
Not that it *really* matters. I cna't remember what my fave relativity
textbook even uses (Van Bladel, Relativity and Engineering (or similar))
Which reminds me, do you know Van Bladel's electromagnetics textbook? Our
library has no copy to check. I hear from one person that it is deep and
dense - he suggested Landau & Lifshitz as the closest other book.
I will try and lay my hands on a copy of the book.
If you're willing to buy, the Dover edition is under US$10. I had to do
the paperwork to extract a copy from the library warehouse; seems nobody
had borrowed it for many years.
--
Timo
.
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| User: "Franz Heymann" |
|
| Title: Re: Physics Essays - weird journal? |
29 Dec 2004 05:02:05 PM |
|
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"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote in message
news:Pine.OSF.4.58.0412300621210.1707@dingo.cc.uq.edu.au...
On Wed, 29 Dec 2004, Franz Heymann wrote:
"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote:
Apart from being interested in your general impressions, Post is
very
pro-SI. I was wondering what a member of the anti-SI old
guard would say.
You know well what I think of SI, so I won't be responsible for
opening that can of worms yet again.
{:-))
Your SI tirades make for interesting reading, at any rate. Me, I use
SI, I
teach SI. Perhaps this results from the trauma of doing a PhD in
astrophysics (being the last refuge of the anti-SI outside of fields
where
it actually makes sense to not use SI).
I, too, taught SI. I used Gaussian in personal work, as did all my
colleagues, except when doing electrical circuit calculations.
The other fun thing is he uses (t,x,y,z) as
4-coordinates, so not the usual metric tensor.
I hope he does use coefficients -1,1,1,1
If you mean signs -+++, I forget, and left the book at work for the
holidays, so can't check for a while.
Same thing?
Post's point is (I think) that c being a fundamental property of
space-time, the metric tensor is its proper home, rather than hiding
it in
the coordinates, or worse, choosing units with c = 1 in order to
hide it
as completely as possible.
I used to use the Minkowski metric in my teaching days, with ict
for
the fourth component of the position vector.
Ack! Complex coordinates to maintain maximal Euclideanness!
It worked a dream.
I started teaching relativity with only a fuzzy recollection of what
I'd
done as a student half a lifetime ago. Teaching is the true way to
learn
something well. I (so far) follow Jackson and use (iirc)
+1,-1,-1,-1.
Not that it *really* matters. I cna't remember what my fave
relativity
textbook even uses (Van Bladel, Relativity and Engineering (or
similar))
Which reminds me, do you know Van Bladel's electromagnetics
textbook?
No. I confess complete ignorance.
Our
library has no copy to check. I hear from one person that it is deep
and
dense - he suggested Landau & Lifshitz as the closest other book.
I will try and lay my hands on a copy of the book.
If you're willing to buy, the Dover edition is under US$10. I had to
do
the paperwork to extract a copy from the library warehouse; seems
nobody
had borrowed it for many years.
I'll get it.
Franz
.
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| User: "TimoAllan NIEMINEN" |
|
| Title: Re: Physics Essays - weird journal? |
30 Dec 2004 02:35:16 AM |
|
|
On Wed, 29 Dec 2004, Franz Heymann wrote:
"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote:
Your SI tirades make for interesting reading, at any rate. Me, I use
SI, I
teach SI. Perhaps this results from the trauma of doing a PhD in
astrophysics (being the last refuge of the anti-SI outside of fields
where
it actually makes sense to not use SI).
I, too, taught SI. I used Gaussian in personal work, as did all my
colleagues, except when doing electrical circuit calculations.
Did they force you to teach in SI? Or were you teaching engineers?
Given that the literature (even recent papers) is mixed SI/Gaussian, it's
probably a good thing for students to be made to deal with both.
My opinion is that relativistic EM theory should be done in the same units
as the usual "conventional" stuff, especially relativistic EM with
material media. I don't see any harm in teaching an advanced course to
physicists in Gaussian units, and some good if previous courses have been
SI. However, I don't want to do that.
At the moment we're using our own private units in the heart of our
computer code. One day it will cause me trouble when I need to actually
calculate an electric field amplitude in real units, instead of
watts^(1/2).
The actual numbers we use all come out in photon-normalised units eg
torque and angular momentum densities and fluxes all in hbar per photon.
The other fun thing is he uses (t,x,y,z) as
4-coordinates, so not the usual metric tensor.
I hope he does use coefficients -1,1,1,1
If you mean signs -+++, I forget, and left the book at work for the
holidays, so can't check for a while.
Same thing?
Depending on what you meant, perhaps. Using (t,x,y,z) means one doesn't
have a metric tensor with diagonal -1,1,1,1 unless one chooses very
special units for time (or position).
Post's point is (I think) that c being a fundamental property of
space-time, the metric tensor is its proper home, rather than hiding
it in
the coordinates, or worse, choosing units with c = 1 in order to
hide it
as completely as possible.
I used to use the Minkowski metric in my teaching days, with ict
for
the fourth component of the position vector.
Ack! Complex coordinates to maintain maximal Euclideanness!
It worked a dream.
I think Post has a (brief) rant against that practice. I think we got our
undergrad relativity course that way, and it didn't work a dream. Not that
that was the fault of ict. I forget what we got in our graduate EM course,
but I do remember it being a most excellent course. When I took it over
many years later I had to relearn everything, but that's life. My goal is
to make the course equally excellent as my precedent's.
--
Timo
.
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| User: "Franz Heymann" |
|
| Title: Re: Physics Essays - weird journal? |
30 Dec 2004 11:48:20 AM |
|
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"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote in message
news:Pine.OSF.4.58.0412301751370.27117@dingo.cc.uq.edu.au...
On Wed, 29 Dec 2004, Franz Heymann wrote:
"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote:
Your SI tirades make for interesting reading, at any rate. Me, I
use
SI, I
teach SI. Perhaps this results from the trauma of doing a PhD in
astrophysics (being the last refuge of the anti-SI outside of
fields
where
it actually makes sense to not use SI).
I, too, taught SI. I used Gaussian in personal work, as did all
my
colleagues, except when doing electrical circuit calculations.
Did they force you to teach in SI? Or were you teaching engineers?
There were no rules as to what we had to or had not to teach. In my
case, it was necessary to teach SI because at that time I was teaching
Elec & Mag, and the textbvook which I preferred (Harnwell) was very
good indeed, except for the fact that it used SI units. Incidentally,
I am a renegade engineer-turned -physicist, and I was actually taught
in SI and foot-pound-second units. The former for all things
electrical and the latter for all things mechanical.
Given that the literature (even recent papers) is mixed SI/Gaussian,
it's
probably a good thing for students to be made to deal with both.
Actually, more than one of us spent some time discussing the
relationships between units with the students.
My opinion is that relativistic EM theory should be done in the same
units
as the usual "conventional" stuff, especially relativistic EM with
material media. I don't see any harm in teaching an advanced course
to
physicists in Gaussian units, and some good if previous courses have
been
SI. However, I don't want to do that.
At the moment we're using our own private units in the heart of our
computer code. One day it will cause me trouble when I need to
actually
calculate an electric field amplitude in real units, instead of
watts^(1/2).
The actual numbers we use all come out in photon-normalised units eg
torque and angular momentum densities and fluxes all in hbar per
photon.
You are leading me to confess that I have a preference for setting up
my equations using entirly "local" units. As a trivial example, when
calculaing an orbit, I would express positions and times in units of
some salient dimension or time in the problem at hand, and force in
terms of the force needed to produce an orit with a radius 1 (in my
then already chosen spatial units). It usually results in
calculations in which all the numerical quantities come in the ball
park of 1, instead of ranging anywhere between 10^-10 and 10^10.
The other fun thing is he uses (t,x,y,z) as
4-coordinates, so not the usual metric tensor.
I hope he does use coefficients -1,1,1,1
If you mean signs -+++, I forget, and left the book at work for
the
holidays, so can't check for a while.
Same thing?
Depending on what you meant, perhaps. Using (t,x,y,z) means one
doesn't
have a metric tensor with diagonal -1,1,1,1 unless one chooses very
special units for time (or position).
In that kind of "geometric" work, I usually put c = 1, meaning that
my time unit is the time taken for light to travel 1 metre.
Post's point is (I think) that c being a fundamental property of
space-time, the metric tensor is its proper home, rather than
hiding
it in
the coordinates, or worse, choosing units with c = 1 in order to
hide it
as completely as possible.
I used to use the Minkowski metric in my teaching days, with
ict
for
the fourth component of the position vector.
Ack! Complex coordinates to maintain maximal Euclideanness!
It worked a dream.
I think Post has a (brief) rant against that practice. I think we
got our
undergrad relativity course that way, and it didn't work a dream.
Not that
that was the fault of ict. I forget what we got in our graduate EM
course,
but I do remember it being a most excellent course. When I took it
over
many years later I had to relearn everything, but that's life. My
goal is
to make the course equally excellent as my precedent's.
A worthy aim.
Franz
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| User: "Timo Nieminen" |
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| Title: Re: Physics Essays - weird journal? |
30 Dec 2004 04:12:56 PM |
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On Thu, 30 Dec 2004, Franz Heymann wrote:
"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote:
On Wed, 29 Dec 2004, Franz Heymann wrote:
I, too, taught SI. I used Gaussian in personal work, as did all
my
colleagues, except when doing electrical circuit calculations.
Did they force you to teach in SI? Or were you teaching engineers?
There were no rules as to what we had to or had not to teach. In my
case, it was necessary to teach SI because at that time I was teaching
Elec & Mag, and the textbvook which I preferred (Harnwell) was very
good indeed, except for the fact that it used SI units.
[cut]
Actually, more than one of us spent some time discussing the
relationships between units with the students.
Discussion at least makes students aware that other systems of units
exist. Forcing students to actually use different systems will bring a
whole new level of familiarity.
Your students would have hated it if you taught them a Gaussian course
with an SI text, but it might have been good for them. Unnecessary
confusion for undergrads, but good for graduate students who'll actually
deal with the horrible mixed bag of units out there.
The worst I have to deal with, worse than units, is the existence of about
16 different conventions for vector wavefunctions in spherical
coordinates. That I would not inflict on students in coursework.
The actual numbers we use all come out in photon-normalised units eg
torque and angular momentum densities and fluxes all in hbar per
photon.
You are leading me to confess that I have a preference for setting up
my equations using entirly "local" units. As a trivial example, when
calculaing an orbit, I would express positions and times in units of
some salient dimension or time in the problem at hand, and force in
terms of the force needed to produce an orit with a radius 1 (in my
then already chosen spatial units). It usually results in
calculations in which all the numerical quantities come in the ball
park of 1, instead of ranging anywhere between 10^-10 and 10^10.
Standard practice everywhere, of course. The trouble comes when
translating these into what one actually measures. In principle, this
should be no trouble, but in practice ...
In that kind of "geometric" work, I usually put c = 1, meaning that
my time unit is the time taken for light to travel 1 metre.
It's clean and elegant. Make students deal with the ugly. Easy to go from
ugly to clean simply by erasing all of the "c"s. The reverse is far more
difficult.
PS For some further interesting reading, try the "Japanese papers" on
Alain Bossavit's home page (google finds with ease).
--
Timo
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| User: "Franz Heymann" |
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| Title: Re: Physics Essays - weird journal? |
31 Dec 2004 08:57:51 AM |
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"Timo Nieminen" <uqtniemi@mailbox.uq.edu.au> wrote in message
news:Pine.OSF.4.58.0412310751230.6408@dingo.cc.uq.edu.au...
On Thu, 30 Dec 2004, Franz Heymann wrote:
"TimoAllan NIEMINEN" <uqtniemi@mailbox.uq.edu.au> wrote:
On Wed, 29 Dec 2004, Franz Heymann wrote:
I, too, taught SI. I used Gaussian in personal work, as did
all
my
colleagues, except when doing electrical circuit calculations.
Did they force you to teach in SI? Or were you teaching
engineers?
There were no rules as to what we had to or had not to teach. In
my
case, it was necessary to teach SI because at that time I was
teaching
Elec & Mag, and the textbvook which I preferred (Harnwell) was
very
good indeed, except for the fact that it used SI units.
[cut]
Actually, more than one of us spent some time discussing the
relationships between units with the students.
Discussion at least makes students aware that other systems of units
exist. Forcing students to actually use different systems will bring
a
whole new level of familiarity.
Your students would have hated it if you taught them a Gaussian
course
with an SI text, but it might have been good for them.
{:-((
Unnecessary
confusion for undergrads, but good for graduate students who'll
actually
deal with the horrible mixed bag of units out there.
The worst I have to deal with, worse than units, is the existence of
about
16 different conventions for vector wavefunctions in spherical
coordinates. That I would not inflict on students in coursework.
I know what you mean.
The actual numbers we use all come out in photon-normalised
units eg
torque and angular momentum densities and fluxes all in hbar per
photon.
You are leading me to confess that I have a preference for setting
up
my equations using entirly "local" units. As a trivial example,
when
calculaing an orbit, I would express positions and times in units
of
some salient dimension or time in the problem at hand, and force
in
terms of the force needed to produce an orit with a radius 1 (in
my
then already chosen spatial units). It usually results in
calculations in which all the numerical quantities come in the
ball
park of 1, instead of ranging anywhere between 10^-10 and 10^10.
Standard practice everywhere, of course. The trouble comes when
translating these into what one actually measures. In principle,
this
should be no trouble, but in practice ...
In that kind of "geometric" work, I usually put c = 1, meaning
that
my time unit is the time taken for light to travel 1 metre.
It's clean and elegant. Make students deal with the ugly. Easy to go
from
ugly to clean simply by erasing all of the "c"s. The reverse is far
more
difficult.
{:-))
PS For some further interesting reading, try the "Japanese papers"
on
Alain Bossavit's home page (google finds with ease).
I'll have a look
A happy New Year to you and yours,
Franz
--
Timo
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| User: "Andy Resnick" |
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| Title: Re: Physics Essays - weird journal? |
27 Dec 2004 10:33:04 AM |
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Timo Nieminen wrote:
On Thu, 23 Dec 2004, Franz Heymann wrote:
Quite.
To change the topic, are you familiar with E. J. Post, "Formal structure
of electromagnetics"? If so, what do you think of the book?
Have it, and tried to read it. It reminded me of Truesdell's approach
to mechanics- the creation of 'rational electromagnetics'. I'll
probably try to read it again.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
CWRU School of Medicine
tanspose 'op' for mail
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| User: "TimoAllan NIEMINEN" |
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| Title: Re: Physics Essays - weird journal? |
29 Dec 2004 12:23:33 AM |
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On Mon, 27 Dec 2004, Andy Resnick wrote:
Timo Nieminen wrote:
Have it, and tried to read it. It reminded me of Truesdell's approach
to mechanics- the creation of 'rational electromagnetics'. I'll
probably try to read it again.
It's been my commuting reading for a while. Such a skinny little book,
such a long time to read it ...
Post's strongly-stated SIism is a bit unusual for a book of its age. But
generally very elegant and nice. Read a book chapter by Post is a recent
book, which inspired me to seek it out. Now to decide how much of it to
inflict on my students next year.
--
Timo
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| User: "Andy Resnick" |
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| Title: Re: Physics Essays - weird journal? |
22 Dec 2004 02:42:45 PM |
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Damir Zucic wrote:
Hi everybody,
I am curious about the journal "Physics Essays". What kind of journal is
that?
<snip>
I've read a few articles from the Journal (not the two mentioned), and I
recognize two names on the editorial board (Kruskal and Scully). My
recollection is that the Journal is somewhat on the fringe of science,
something like controlled, semi-rigorous free association. A lot of
speculation, not a lot of concrete examples. Not one of the first-rank
Journals, but not at the bottom, either. My library doesn't have
electronic access, so that (probably) means the department doesn't feel
the need to pay for access.
And, for what it's worth, every Journal out there calls itself "world
class". Why would nayone want to subscribe to, or submit articles to, a
Journal that advertises itself as "second rate"? (The Journal of
Irreproducible Results and its brethren omitted from consideration)
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
CWRU School of Medicine
tanspose 'op' for mail
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| User: "Bjoern Feuerbacher" |
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| Title: Re: Physics Essays - weird journal? |
22 Dec 2004 07:23:54 AM |
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Damir Zucic wrote:
[snip]
These two articles, "Quantization in Classical Electrodynamics"
(vol. 15, number 1 (2002), p 41) and "Absorption and Emission of
Radiation
by an Atomic Ascillator" (vol. 16, number 2 (2003), p. 162) try to
explain some quantum phenomena by pure classical electrodynamics.
"explain" in what sense? Does he give quantitative descriptions?
Does he manage to derive Planck's constant h (or the hydrogen
energy levels, or something else involving h) using only
electrodynamics? If yes, that would be worth a Nobel prize; if
no, his work has no value.
It is quite hard to read these two articles, but I have found some weird
things there. Here is just a short selection:
(1) It is assumed, that the total radiation of an electron in the atom is
the sum of the radiations of two dipoles, which are put perpendicular
to each other. What forms two dipoles in a hydrogen atom?
Apparently he assumes that the electron moves on circular orbits.
Such a movement can be described by two perpendicular oscillating
dipoles. That's a quite standard practice.
[snip]
(4) There is a consistent mixing of macroscopic equations and microscopic
phenomena. Why reviewers accepted that "... similar to the macroscopic
area, there is also a displacement current in the microscopic area
generated by the circular motion of an electron ..."?
How could that motion generate a displacement current???
[snip]
Any information about Physics Essays will be appreciated.
Sorry, don't know about that.
[snip]
Bye,
Bjoern
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