Newsgroup sci.physics 216362

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John A. Stanley wrote:
> 
> In article , meron@cars3.uchicago.edu wrote:
> >In article <32DE2D18.1D3D@cdc.com>, Dave Monroe  writes:
> >>Saw on the CBS evening news last night where
> >>the US shipped 80 grams of plutonium to Viet Nam
> >>prior to the war for one reason or another.
> >>When the commies overran the south, our guys
> >>grabbed the wrong container and the Viet Cong
> >>were left with the goods.
> >>
> >>Anybody know if 80 grams of plutonium could be
> >>used to make a small weapon?
> >>
> >No, that's too little.
> 
> Depends on the type of weapon.... 80 grams of plutonium could make a
> whole lot of people die of cancer.
> 
A purist would call that a radiological weapon, not a nuclear weapon.
Dennis Nelson

In article , Goddess
 writes
>In article , Nick Sexton
> writes
>>In article <5as1hf$7jm@news.fsu.edu>, Jim Carr 
>>writes
>>>Rebecca Harris  writes
>>>}STARGRINDER  writes
>>>}>
>>>}>get a life!
>>>} 
>>>} Hear Hear!
>>>
>>>Goddess  writes:
>>>>
>>>>Yeah! I don't see why they bother with these posts on here. Why don't they 
>>post
>>>>it on some maths chat group?
>>>
>>> To those of us reading the crosspost in sci.physics or sci.math, the 
>>> concern is that completely misleading junk such as 
>>>
>>>: Comment: Note that atoms (atoms) = atoms
>>>:
>>>:       It seems that squaring an item (not a unit of
>>>: measurement) equals the item.  What do you think?
>>>
>>> is being posted in k12 groups where it could confuse impressionable 
>>> children.  If Kaufman was only talking to teachers, who should have 
>>> the sense to ignore him, it would not be quite so bad. 
>>>
>>
>>I'd just like to make a point. To whoever posts the educational stuff.
>>Listen up.
>>
>>k12.chat.junior is a chat group. People talk and stuff. What really
>>annoys people here is the educational stuff that gets posted. I don't
>>think many people read it, anyway. (And those who do are probably on
>>k12.ed.math anyway) So if you want to make us happy, then _please_ don't
>>send stuff to this group. s'just a thought.
>
>Don't write 'it's just a thought'! Sweetie, nobody's goin' to listen to ya if ya
>say that! You gotta tell em out right. Just like that! It's not just a thought,
>cause everybodys thinkin' it, so SPEAK OUT!
I just write "It's just a thought" so that it doesn't offend anyone if
they disagree with it. Not that it works, or anything.
-- 
Nick

One product I have seen is a small pump gizmo that screws onto a pop
bottle as a cap. It is used to increase the pressure inside the bottle to
prevent loss of carbonation. While that seems reasonable its performance
has not impressed me. Furthermore, I have had some success preserving
carbonation by a technique that seems totally opposite, and
counterintuitive. Upon opening a 2-litre bottle of pop, I squeeze the
bottle to displace most of the air before putting the cap back on. I
haven't run any scientific tests yet (e.g. with a control) because I can't
afford to piss away too much money on pop, but I'm wondering if anyone
knows whether or not this makes sense. Please email me as I am not on this
newsgroup often.
Mike

Peter Berdeklis  wrote:
>
>
>I've been thinking about this one a long time, asked a few people, got no 
>satisfactory answers.  Hope you can help.
>
>The Situation:
>
>Your standing in an almost perfect Faraday cage.  There is just one small 
>hole in the cage wall big enough to throw a quarter through without 
>hitting the wall.  Your Faraday cage is perfectly insulated from the 
>ground.  Now your cage gets hit by lightning.  
>
>(Obviously this is an extreme case of being in a car hit by lightning.)
>
>
>The Physics:
>
>Since you are in a Faraday cage there is no potential gradient inside.  
>Therefore no charge enters the cage beyond some skin depth on the outer 
>surface of the cage, which we will assume is small compared to the wall 
>thickness.
>
>Although there is no potential grad. inside the cage, the entire cage has 
>a significant potential with respect to the ground because the lightning 
>stroke just dumped 20 C of charge on it.
>
>You and the quarters you are carrying are at the same potential as the
>cage, well above the potential of the ground.  When you throw a quarter
>out the small hole you should get a spark as the quarter nears the 
>ground.  If you could jump out of the cage you should be hit by a similar 
>spark, even if you are not in contact with the cage after you jump.
>
>
>The Problem:
>
>No charge entered the Faraday cage (it is all on the surface of the cage). 
>What cause the increase in electrical potential energy inside the cage that 
>brings you and the quarters to the potential of the cage?  What changes 
>in your physical-electrical state?
>
>
>Maybe this is obvious to someone, but it has had me stumped for a while.  
The 20C or charge is confined to the outside of the Faraday cage, where 
all good mobile charge flows to equilibrium in conducting bodies.  The 
FIRST spark occurs when the quarter exits the cage and encounters 20C or 
charge at a million volts.  Also note that the edge of the hole has a 
very small radius of curvature, and the electric field will be 
concentrated there.
The SECOND spark occurs as the charged quarter aproaches the ground.
Humans work the same way, except for the screaming and convulsions
CLEAR!
-- 
Alan "Uncle Al" Schwartz
UncleAl0@ix.netcom.com ("zero" before @)
http://www.ultra.net.au/~wisby/uncleal.htm
 (Toxic URL! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?"  The Net!

> >The Situation:
> >
> >Your standing in an almost perfect Faraday cage.  There is just one small 
> >hole in the cage wall big enough to throw a quarter through without 
> >hitting the wall.  Your Faraday cage is perfectly insulated from the 
> >ground.  Now your cage gets hit by lightning.  
	If lightning struck the Faraday cage, would you necessarily be
insulated on the inside even without a hole? I thought my physics prof
said that a changing electric field will momentarily cause electrons to
rearrange themselves. Might a temporary field then be produced inside the
cage?
	This is kind of off the subject, but there's something I've always
wondered about conducting materials. 
	1. If you place a charge on the surface of a hollow, conducting
sphere, then there will be no field within the sphere. If the sphere has a
net negative charge, then an electron at any point within the hollow sphere
would not feel a net force.
	2. If you place a net charge on a conducting sphere, the charges
will rearrange themselves until they are on the outside of the sphere.  
This arrangement looks very similar to the charge on a hollow sphere.
Likely premature conclusion: If you place an electric charge inside the a
charged, conducting sphere, this charge should not be subjected to a net
force in any direction. The charge should remain where it was injected
into the sphere.
	The only problem is that this seems to disagree with the results
of experiment. Any ideas? 
					-Andrew

Jeff Candy  wrote in article
<01bc0492$5220d130$38c00bce@TIME>...
> 
> In the electron version of the EPR paradox, the two 
> electrons are described collectively as a *single* spin singlet 
> state:
> 
>                        |+-> - |-+>
>                        -----------
>                          Sqrt(2)
>                 
I don't believe there is anything different going on in the electron case. 
(Note that I am not familiar with the details of this analysis, so I'm just
groping in the dark.)  In the analysis of the Aspect experimental design,
the pair of photons are defined through the use of a single state vector,
exactly as in the electron case.  And it works.  I'm postulating that this
is merely a mathematical relationship, and not a physical connection of the
two particles in question.
Consider what normally goes on in a QM analysis.  We start by deciding how
many degrees of freedom are needed to describe the system under study.  Any
eigenstate used to describe the system needs this many degrees of freedom. 
But separate eigenstates are added together with complex coefficients. 
Thus we have introduced a larger space to describe the system than is
apparently needed.  In the specific case of the EPR thought experiment, we
then go on to enforce a conservation rule, namely that we know the total
spin of the two particles.  There is no way to know this from an
observation on one of the particles.  In fact, we only know it because we
know the origin of the particles, i.e. the original state of the system at
some time in the past.  (To invent a catch-phrase, we have introduced
"non-local knowledge" into our mathematical treatment.)  This seems to me
entirely analogous to the well-known classical method of Lagrange
multipliers.  An additional degree of freedom is added to the Lagrangian
(or Hamiltonian, whichever, it's been a long time since grad school), and a
constraint is added in the form of a separate equation.  The constraint is
only added back at the end to collapse the expanded system back to the real
system under study.  No one expects the Lagrangian with the extra degree of
freedom to physically describe the system under study.  We only use this
Lagrangian as a computational aid.  Some quantum field theory techniques
such as spontaneous symmetry breaking and guage theories seem to be using
very similar techniques.
> you must ask what in particular is wrong, or rather nonphysical, about
the 
> spin-singlet state itself!  
> 
The spin-singlet state, IMHO, is non-physical.  There's nothing wrong with
it.  It's a convenient mathematical representation of the system under
study including constraints we've inferred through knowledge of
conservation laws.  It does not correspond one-to-one with the system under
study because we've introduced "imaginary" degrees of freedom.  (The
evocative nature of that term is merely fortuitous.)
My problem lies entirely in the mathematics.  I don't understand why the
generalization from a Euclidean vector space to a complex vector space buys
us so much computational power.  (Of course, why is an illegal question...)
 Of course it's possible that the universe really is a Hilbert space, and
the non-locality is a physical phenomenon.  I prefer to believe, until I'm
convinced otherwise, that the Hilbert space is merely a convenient
mathematical tool that does not have direct physical implications.  That
statement, at this point, is roughly equivalent to saying I believe God
maintains a watch over all correlated particles, and enforces conservation
rules on a case-by-case basis.  I believe, however, that there is a way to
prove what I'm saying.  I believe that the answer lies in something
analogous to the concept of meta-languages discussed by Hofstadter in
"Goedel, Escher, Bach."  I would like to invent a new mathematical system
in which the steps followed by the mathemetician are encoded in the
mathematics.  Put in less grandiose terms, I would like to follow the
implications of each step in the analysis of a system as to how they affect
the relationship of the theory to the system under study.  I believe the
answer is not very far out, i.e. QM is extremely (though somewhat
accidentally) close.  I wish I knew more Complex Analysis, Conformal Field
Theories, etc...
Am I missing something?  Didn't Dirac basically say, "Let's do it this way
and see what happens?"  Is there some physical or philosophical meaning to
a complex vector space?  Can I come up with one more rhetorical question?
> Consider spin-1/2 systems in general.  A (2 pi) rotation about any 
> axis is *not* an identity map: 
> 
>                        R(2 pi) |a> = -|a>
> 
> Does that in itself mean the QM description of spin-1/2 systems 
> is "wrong"?
>
I have no problem whatsoever with this.  It's counter-intuitive, but so are
lots of truths.  It's accepted as fact that the negative sign has no
physical consequences until interference effects come into play, and then
we're back to the same situation:  we're describing interactions among
separate states and may be assuming constraints that destroy the one-to-one
correspondence of equation to physical system.
The thing I don't understand about spin is basically embodied in the
Stern-Gerlach experiments.  I can find no intuitive justification for the
quantization of the z-component of spin.  In the case of electronic orbits,
quantization occurs because only specific energies can give closed
(bound-state) orbits.  This is at least visualizable.  But in the case of a
magnetic moment being deflected by a magnetic field, it's not bound and I
don't understand why discrete deflections occur.  Oh, well, one can only
keep trying.
> -------------------------------------------------------------------
> Jeff Candy                        The University of Texas at Austin
> Institute for Fusion Studies      Austin, Texas
> -------------------------------------------------------------------
> 
Thank you for your comments.
Timothy J. Ebben
2470 Island Drive #304
Spring Park, MN  55384
"For this is all a dream we dreamed
 One afternoon long ago.."

In article <32DF4AA2.693A@telepath.com>,
Vincent Johns   wrote:
>(posted & emailed)
>Herman Rubin  wrote:
>> In article <01bc034b$0f28e4a0$22b32e9c@goldbach.idcnet.com>,
>> goldbach  wrote:
>> >[...]
>> >The numeral, which is
>> >a symbol-similar to a word in its use, is the means
>> >which a mind symbolizes the concept so that it can
>> >use it as a unit for purposes of thought.
>> This is a grave error.  It is the cause of much misunderstanding
>> of mathematical concepts by far too many people.  The use of
>> numerals is a means of communication, and the use of these to
>> think about numbers is one of the reasons why people cannot
>> handle mathematical concepts.  The number which is represented
>> as "30" in the usual way, or XXX in Roman numerals, or as 36
>> in octal, or as '''''''''''''''''''''''''''''' in tick marks,
>> or as 11110 in binary is the same number, and its properties
>> are the same, no matter how it is represented.
>The properties of the number are the same, regardless of the 
>system of numeration, yet what one can do with it (as in other 
>fields of endeavor) may well depend on the notational system 
>used.  It is my impression that the ancient Greeks, though their 
>geometry was well developed, did not do nearly as much with 
>arithmetic because of their klutzy (i.e., inconvenient) numbering 
>system.  Numerical ideas were not as easy to express as they 
>might have been with a different system, and this hampered 
>mathematical thought.
There numbering system had nothing to do with it.  There is little
difference between using different symbols for multiples of different
powers of 10 and using the same symbols for each digit.  One could
even use a symbol for each power of 10 and repeat it the requisite
number of times.  But this is unimportant.
>We use and manipulate algebraic equations (using a notation 
>which was not available to the Greeks) to solve problems,
This is what the Greeks were lacking.  How they wrote numbers down
has absolutely nothing to do with it.  The idea of using a symbol
for a number was invented by Diophantus around 300 AD.  Having our
type of representation of numbers would have made no difference
whatever.  The Babylonians had a system much like the "Arabic"
numerals, only base 60.  But it was the lack of algebra which
was the problem, and not the way numbers were written.
Euclid, in showing that the square root of 2 is irrational, had
to use words; it was a half a millennium later that the notion of
variable was invented.  I believe that we should teach this in
first grade, and USE it to teach the properties of numbers, and
also to teach arithmetic.  Although he uses labels for points in
proofs, his statements of theorems are often difficult, because
only words are used.  Even allowing variable points outside of
proofs would simplify the statements.
>often without giving any thought to the physical interpretation 
>that one might give to intermediate results.  There is no need
>to keep in mind the interactions of, say, four variables.
>Given modern notation, all we need do is translate a suitable
>problem into standard algebraic notation; then the standard
>operations on the symbols, plus a bit of insight, lead one 
>quickly to a solution which is easily translated back to 
>physical terms.  The notation serves well for communication 
>(e.g., for convincing someone that one's solution is valid) but 
>also for providing a mechanism for deriving a solution, even 
>without any need for communication with someone else.  Sometimes 
>one needs only a result and does not need to formulate a proof.
This linguistic use of variables for communication is something
which I have been pushing for years.  But it seems to be meeting
with massive resistance; there is the widespread belief that 
symbolism is unimportant, and that one should learn how to solve
the problems without formulating them.  
We find that those who have had too much manipulation have much
greater difficulty in being willing or able to learn to use
precise terminology.  It is not the arithmetic notation or
computational facility which is the problem, but the inability
to learn to READ and WRITE and SPEAK symbolically.
-- 
This address is for information only.  I do not claim that these views
are those of the Statistics Department or of Purdue University.
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
hrubin@stat.purdue.edu         Phone: (317)494-6054   FAX: (317)494-0558

huber@laser24.unibe.ch (Thomas Huber) wrote:
>Hello,
>Could anyone please explain to me the principle of
>"charge transfer absorption", which occurs in crystals
>somewhere in the ultraviolet. References are welcome,
>too, of course
>
Metal-to-ligand charge transfer is an allowed or strongly allowed 
process.  Look up references on ligand field theory (Might start with 
Figgis).  The absorptions tend to have very large oscillator strengths, 
and can occur anywhere from the UV through the visible into the IR.  
Spreading out charge is a good thing.  Consider the Creutz-Taube ion.
Consider Fe(II) or Fe(III), neither of which have strong optical 
transitions even when complexed in a strong ligand field like that of 
ammonia.  Compare (H3N)6Fe(II or III) with (H2O)6Fe(II or II), and 
(H2O)4Cu(II) and (H3N)4Cu(II).  Phenanthroline has no visible 
transitions.  (phen)3Fe(II) is a brilliant deep red; (phen)3Fe(III) is a 
brilliant deep blue.  Charge transfer to/from the organic ligand does it.
One could tinker with the Fe system to give it an intense, allowed 
transition.  Fe(II,III) oxide, Fe3O4, is black.  Similar spinel or 
inverse spinel structures like copper chromite are incredibly black.
-- 
Alan "Uncle Al" Schwartz
UncleAl0@ix.netcom.com ("zero" before @)
http://www.ultra.net.au/~wisby/uncleal.htm
 (Toxic URL! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?"  The Net!