HDTenEightyP/NetNews huggingface dataset:
From: kriman@acsu.buffalo.edu (Alfred M. Kriman)
Newsgroups: sci.physics
Subject: Re: ... an infinite mesh of 1ohm resistors ...
Summary: A pointer to a published instance of the problem.
Date: 30 Jul 92 22:36:38 GMT
Organization: "UB" = State Univ. of New York at Buffalo

In article <1992Jul30.025452.23086@mixcom.com> Adam Costello ttyytt@mixcom.com
writes:
>In article <1992Jul28.093201.10671@fs7.ece.cmu.edu> snyder@henry.ece.cmu.edu
(John Snyder) writes:
>>[...]
>>no capacitors present.  We solved *MANY* such problems in Electrical
>>Engineering 101 (groan! (:^)).  The current goes in at terminal A, and 
>>out at terminal B.  I cannot seem to locate the original problem, but my 
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>[...]
>the current comes out terminal B, but doesn't go in anywhere.  I doubt
>you ever did anything like this in EE 101.  (I sure didn't!)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>By the way, if you've forgotten the original problem, here it is in a
>nutshell:
>
>What is the resistance between the two ends of any resistor in an
>infinite square lattice of 1 ohm resistors?

	Could this be a generational thing?  This is problem 2.27 of
_Introduction to Modern Network Synthesis_, by M. E. Van Valkenburg (Wiley,
New York, 1960).  Although it is intended that much of the book be covered in
a one-semester undergraduate course, "[w]e assume that the reader is familiar
with the elementary methods of network analysis."  On the third hand, chap. 2
is really review.  This is too sweet a problem not to appear in other texts,
but I haven't seen it.  (It's not in Van Valkenburg's more elementary book,
and not in any of half a dozen rather more recent textbooks scattered around
here.)
	Also, much of the byegone emphasis on network theorems and equivalent-
circuit transformations was intended to ease the load on engineers doing
hand calculations and assisted only by steam-powered abaci.  Nowadays, everyone
uses Spice(TM) to figure the dc current in a one-capacitor network.
	Still, it's a shame that more _fun_ problems don't appear in textbooks.

[ I _know_ that the "correct" spelling is _bygone_.]
From: paj@uk.co.gec-mrc (Paul Johnson)
Newsgroups: sci.physics
Subject: Re: Blue Sky
Date: 27 Jul 92 15:20:42 GMT
Reply-To: paj@uk.co.gec-mrc (Paul Johnson)
Organization: GEC-Marconi Research Centre, Great Baddow, UK

In article <1099@kepler1.rentec.com> andrew@rentec.com (Andrew Mullhaupt) writes:
>Why is the sky blue?
>
>Later,
>Andrew Mullhaupt
>
>P. S. I have an idea, but I'd like to collect answers from physicists.
>I sometimes use as a philosophical example 'go ask a physicist why the
>sky is blue, and he'll likely say...' and I would like to be honest
>about it. It's been a while since I actually asked any physicists this
>question, so here goes.


In `The Cuckoo's Egg', Clifford Stoll reports an oral exam where one
examiner asked this very question.  Stoll's reply was something along
the lines of "Err.....duh.... scattered light".

The examiner asked Stoll "Could you be more specific".  Stoll made a
more specific reply.  The examiner asked for more details, and so on.

Stoll reports that when he finally finished answering this question
some two hours later, he was covered in sweat and he had covered a
blackboard in equations.
-- 
Paul Johnson (paj@gec-mrc.co.uk).	    | Tel: +44 245 73331 ext 3245
--------------------------------------------+----------------------------------
These ideas and others like them can be had | GEC-Marconi Research is not
for $0.02 each from any reputable idealist. | responsible for my opinions
Xref: sparky sci.physics:11940 sci.astro:8441 sci.philosophy.tech:2899 talk.religion.misc:12946
From: yaron@astro.as.utexas.edu (Yaron Sheffer)
Newsgroups: sci.physics,sci.astro,sci.philosophy.tech,talk.religion.misc
Subject: Re: Structure of Time
Date: 29 Jul 92 15:09:24 GMT
Followup-To: sci.physics
Organization: University of Texas, McDonald Observatory

In article <1992Jul28.102429.1@tnclus.tele.nokia.fi> hporopudas@tnclus.tele.nokia.fi writes:
>   I'am very sorry that I have encounter here many peoples who seems to be
>somekind of representative of "inquisition". I always belived that just
>physicists love the truth most, what ever the truth is.

This one's easy: Truth is measureable in the lab, or observable in the
Universe, and in any case should be consistent and causal with anything
that we have ever observed/measured in the physical cosmos, whether
macroscopically or microscopically, preferably both.

Lots of unfounded nonsense (read: no relationship to past observations,
no testable predictions) which has nothing to do with Truth, is not a sign
of opposing "inquisition" as much as sign of mental deficiency to begin
with. Especially if there's dependence on the miraculous, such as
"revelations" from babies. Geez, get real!

Just my $0.02...
Newsgroups: sci.physics,sci.astro,sci.philosophy.tech,talk.religion.misc
From: ivanitch@cherry.udel.edu (Sandy Ivanitch)
Subject: Re: Structure of Time
Organization: University of Delaware
Date: Thu, 30 Jul 1992 14:55:02 GMT

In article <1992Jul28.175239.10109@hpcvaac.cv.hp.com> billn@hpcvaac.cv.hp.com (bill nelson) writes:
>hporopudas@tnclus.tele.nokia.fi writes:
>: 
>:  Hi !
>: 
>:  Re: Structure of Time
>: 
>: 
>:    I'am very sorry that I have encounter here many peoples who seems to be
>: somekind of representative of "inquisition". I always belived that just
>: physicists love the truth most, what ever the truth is.
>:    These "inquisitors" have contacted to my employer and they have tried
>: to insalt me and my paper. My employment is in danger at the moment.
>
>
>What you have posted does not even begin to follow what is called the 
>scientific method. Physicists love the truth, but random babbling is
 ^^^^^^^^^^^^^^^^^

I have been reading this thread because I have found it entertaining  
but I have to agree with this statement.  I'm not a physics major, I'm
studying archaeology (I know some wouldn't call that a science) but even
in this field the scientific method is the norm.  If your theory can't
be supported by "facts" and figures which can be "duplicated" by someone
else, it isn't going to carry much weight.  Your interpretation of your
daughters drawings and comments may be interpreted in an entirely different
way by someone else.  I may not agree with what you've been saying, but
you are entitled to your own opinion and your employer should not use that
as a grounds for terminating your employment.


-- 
@             Sandra Ivanitch		@            Archaeology:             @
@      ivanitch@freezer.cns.udel.edu    @  It may not have much of a future,  @
@           				@   but it has one hell of a past!    @
From: mitsu@nic.cerf.net (Mitsuharu Hadeishi)
Newsgroups: sci.physics
Subject: Re: ***********MIND-BLOWING GEDANKENEXPERIMENT**********
Date: 25 Jul 92 05:59:16 GMT
Organization: CERFnet



In response to the argument having to do with the pair-singularity "issue",
Jack Sarfatti responds:

The argument in message 5 is
from Carlton Caves at USC he sent me a letter and it seems to me to be
totally crazy - a nonsequitor. My pair desnity matrix for both photon
remains Trace 1 after the evolution through the half-wave plate. Probability
is conserved as far as I can see. Where does  |h2> + |v2> and |h2> - |v2>
which are single particle state come from? Certainly not from my total
experimental arrangement. The argument is a total non-sequitor - unless I
am stupid and crazy - which is a possibility of course. It seems to me
that very good physicists become absolutely incompetent and irrational
when faced with my very simple argument. Are they saying that half-wave
plates behave differently for pair correlated light than for uncorrelated
light? That would be an interesting phenomenon it true.
Given [|v1>|v2> + |h1>|h2>]/sqrt2 , if by local unitary evolution the
phase plate sends |v2> -> e^iphi|v2> and the have wave plate sends
|h2> -> |v2> (half wave plates rotate plane of linear polarization by
90 degrees says every optics text book) And I am using exactly the same
method that Wooters and Zurek used to prove that you cannot clone a photon
for arbitrary linear polarization in a laser amplifier which disproved Nick
Herberts FLASH FTL communicator - then evidently by the linearity, unitarity
and superposition principles and by elementary algebra of the distributive
law for kets
The initial entangled state [v1>|v2> + |h1>|h2>]/sqrt2 ->
[|v1> + e^iphi|h1>]|v2>/sqrt2 probability is conserved! p(v1,v2) = 1/2 and
p(h1,v2) = 1/2 { p(v1,h2) = 0, p(h1,h2) = 0, p(v1) = 1/2, p(h1) = 1/2,
p(v2) = 1, p(h2) = 0} so what is this garbage that probability is not
conserved. What false nonsense. What is this garbage that |v2> + |h2>
or |v1> - |h2> have any relevance to the problem whatsoever? Is every
one crazy? (I do not mean everyone I just mean academics in physics
departments - and only a subset of them at that.). I rest my case.
PLEASE PUT THIS ON INTERNET SO THAT THE WORLD CAN JUDGE. Someone out there
must be able to be rational about this. I am quite ready to accept that
I have made some sort of mistake - but the "spin-flip mystery" argument
is total nonsense as far as I can see.


[end quote]


Newsgroups: sci.physics
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: Chaos
Organization: University of Virginia
Date: Thu, 23 Jul 1992 18:53:39 GMT

In article <76441@ut-emx.uucp> johncobb@ut-emx.cc.utexas.edu (John W. Cobb) writes:
>In article <1992Jul20.153122.29180@murdoch.acc.Virginia.EDU>,
>crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:

>|>     This is good, if you take credit for 'chaos theory' for all of the
>|>     work going back to Poincare, then you are left with a dilemma.  Either
>|>     the subject is a rather evolutionary outgrowth of dynamical systems
>|>     theory with the addition of large computers to guide us, in which
>|>     case it seems difficult to justify assigning earthshattering importance
>|>     to it, or it is not, in which case it seems difficult to justify
>|>     taking credit for 90 year old results.
>                                                                        
>I think this point is fallacious. It is like saying that the discovery of the
>double helix structure of DNA is an "evolutionary outgrowth" of x-ray
>crystallography and has no "earthsattering importance". Even Newton admitted
>that if he had voiced some deep and fundamental ideas that he owed a
>debt of gratitude to the giants on whose shoulders he stood. The recent
>flurry of interest in chaos is indeed based upon a long history of previous
>results of great importance, but it is untrue to somehow imply that very
>little of the current work is fundamentally new -- it is.

     I did not say this.  I said that the importance was somewhat overstated
     and oversold.  I still say this.

     I also implied that certain proponents seem to have blinders that
     seem to shield the importance of most work done before about 
     1975.
  
     [stuff deleted]     

>Geometry. That this is an needed task is borne out by many of the comments
>on this newsgroup that reveal both a fundamental misperception about what
>chaos means and a refusal to acknowledge that it fundamentally changes
>notions about dynamics in physical systems where it exists (for example,
>sensitive dependance on initial conditions implies abscence of predictability).

     However, this, as well contains a misconception.  Sensitive dependence
     on initial conditions does not necessarily imply unpredictability of 
     all gauges of a system, just the one to which the system is sensitive.
     (for example the velocities of a fluid system may be completely 
     unstable while the total energy shows a nice smooth bounded behavior.
     If appropriate or possible, one might be better off reformulating the 
     system in terms of total energy and leaving the sensitive dependence 
     in the dustbin.)

                                  dale bass

>john w. cobb
>jwc@fusion.ph.utexas.edu


--
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926
Newsgroups: sci.physics
From: platt@watson.ibm.com (Daniel E. Platt)
Subject: Re: Blue Sky
Date: Wed, 22 Jul 1992 18:06:59 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
Organization: IBM T.J. Watson Research Center

In article <1992Jul22.154233.21594@linus.mitre.org>, m14494@mwvm.mitre.org (Mike White) writes:
|> Andrew Mullhaupt writes:
|> > Why is the sky blue?
|> 
|> You'll get lots and lots of answers, and I'll bet my tenure that not one 
|> of them will address the question "Why?"; they'll all address the question 
|> "How?".  They'll go on and on about scattering of light from Nitrogen 
|> molecules, but the question of "Why?" is much harder.  The mechanism that 
|> makes the sky blue is well understood, but why does that mechanism exist, 
|> instead of one that makes the sky, say, green?  This rapidly gets into 
|> metaphysics; I think the answer has to do with conditions that make it 
|> possible for us to exist to ask the question in the first place.

Let's see... 

	1)	mechanism of light scattering in the atmosphere (Rayleigh 
		scattering, if I remember my Jackson correctly).  This has
		more to do with the properties of light scattering from
		small objects compared to the wavelength than it does
		with what the objects are, if I remember rightly...

        2)	composition of atmosphere... has to do with the evolution 
		of our atmosphere.

	3)	Why our planet had the initial conditions it did (nucleo-
		synthesis, etc, astronomy).

	4)	Why elements, chemicals, nucleii, etc have the structure they
		do (quantum physics, chemistry, nuclear/particle physics).

ALL of those questions are mechanistic at some level (that is, they talk
about 'how').  At this level, there are connections between the 'how' of life
and the 'how' of why the sky is blue (same kinds of chemistry/physics
involved at some level, as well as the natural history of our planet to
produce the correct conditions).  As far as conditions, we can ask 'how not,'
and look at other planets for examples.  As far as mechanism, it is much
harder to ask 'how not,' in that its like asking 'how would it be if
electrons behaved differently... how would life look like, or what color
would the sky be?'  In a way, I think that kind of question is getting closer
to the 'why'...

As an undergrad, I remember something about 'causes' being described this way,

"Why is this a 'table'?"

1)	It is a table because it has for legs supporting a flat top.
	(it is shaped like a table)
2)	It is a table because you can put things on it.
	(it acts like a table)
3)	It is a table because someone made it.
	(it was created to be a table by someone)

There were two other 'causes' in this context that I don't recall.  However,
I think they all tie in with the question of what one can mean by the
question 'why.'  The above description of why the sky is blue covers several
facets of the above meanings of 'why' while only handling mechanistic 'hows.'

You don't want to get stuck in the position of the little child who asks
'why' in response to every explanation...  Ultimately, it has to reduce to
some basis of common experience (agreed standards...).

Dan
From: braham@physics.ubc.ca (Stephen Braham)
Newsgroups: sci.physics
Subject: Re: Quantum Cosmological Boundaries and Determinisim?
Keywords: Quantum cosmology
Date: 23 Jul 92 17:17:41 GMT
Organization: University of British Columbia, Vancouver, B.C., Canada

jtwamley@physics.adelaide.edu.au (Jason Twamley) writes:

>braham@physics.ubc.ca (Stephen Braham) writes:

>>shouldn't be confused with the _dynamical_ collapse of the
>>wavefunction, induced by decoherence processes- that's a statement
>>on a Shroedinger picture density matrix, and ADH is a lot more
>>general than that.
>                                          ^^^^^^^^^^^^^^^^^^^^^^

>Hmmmm... I have head it said that ADH may be too restrictive for any
>system to match up to the Gell-Mann Hartle (GMH) criterion of quai-classical.
>Even Omnes believes that the GMH decoherence criterion is too tough...

Well, the definition of a quasiclassical domain is VERY strong, and
classicality is being redefined. I tend to lean towards the approximate
decoherence ideas, but that causes LOTS of problems (the statements
that Gell-Mann and Hartle make really do need EXTENSIVE improvement).
I'm presently spending time worrying about that, in fact. My biggest
worry is that you then seemed to be forced into needing an interpretation
of the off-diagonal elements in the decoherence functional. These
are NOT connected to the off-diagonal elements in the density matrix,
by the way- old-fashioned S-picture decoherence and ADH are produced
by similar effects (state squeezing, primarily), or so it seems, but
they are very different creatures in reality.


>Jason
		Steve

--
| Name: Stephen P. Braham | Perversion: Quantum Cosmologist|
| Hangout: UBC physics    | Signature:  Euclidean          |
|          Vancouver, BC  |--------------------------------+
|          Canada         | E-mail: braham@physics.ubc.ca  |
From: markc@smsc.sony.com (Mark Corscadden)
Newsgroups: sci.physics
Subject: Re: Calculating the mass of a charged point particle
Date: 30 Jul 92 00:22:02 GMT
Organization: Sony Microsystems Corp, San Jose, CA

In article <1992Jul28.225512.21795@galois.mit.edu> jbaez@riesz.mit.edu (John C. Baez) writes:

|>...
|>This again diverges as r -> 0 unless we fine-tune the bare mass and the charge
|>so that e^2 = Gm^2, i.e.  m = e/sqrt(G).  But now let's steal an idea
|>from general relativity and say that ALL energy contributes to the
|>Status: O
|>
|>source of the gravitational field.  Then we get
|>
|>	m(r) = m + e^2/r - Gm(r)^2/r !
|>...

Opps!  The "Status: O" line was inserted by my mailer because it
saw a line in John's article that started with "from ".  This should
have read:

...
This again diverges as r -> 0 unless we fine-tune the bare mass and the charge
so that e^2 = Gm^2, i.e.  m = e/sqrt(G).  But now let's steal an idea
from general relativity and say that ALL energy contributes to the
source of the gravitational field.  Then we get

	m(r) = m + e^2/r - Gm(r)^2/r !
...

Sorry, I thought if I didn't mention this someone might waste time
wondering how "Status: O" was supposed to fit into the discussion!

Mark Corscadden
markc@smsc.sony.com
work: (408)944-4086
Newsgroups: sci.physics
From: knapp@spot.Colorado.EDU (David Knapp)
Subject: Re: Blue Sky
Organization: University of Colorado, Boulder
Date: Wed, 22 Jul 1992 21:07:24 GMT

In article <1992Jul22.121947.12108@aoa.aoa.utc.com> carl@aoa.aoa.utc.com (Carl Witthoft) writes:
>In article <BrrMJB.Brv@acsu.buffalo.edu> mjb@acsu.buffalo.edu (Matthew J. Bernhardt) writes:
>>andrew@rentec.com (Andrew Mullhaupt) writes:
>>>Why is the sky blue?
>>	I'll bite.  The composition of the Earth's atmosphere (four fifths
>>nitrogen, one fifth oxygen) is such that incoming light is refracted to make
>>the sky appear blue.
>x
>Get real.  It's Rayleigh scattering.
>Short answer: this means particle scattering is related to wavelength,
>and shortwave, i.e. blue, scatters more.  Hence blue sky.

Get real yourself!  You didn't even bother to mention if it was stokes 
or anti-stokes! 
 
;-/




-- 
David Knapp                                      University of Colorado, Boulder
Highly Opinionated, Elderly and                      knapp@spot.colorad.edu
Perpetual Student of Chemistry and Physics.
            Write me for an argument on your favorite subject.
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Twins Paradox Resolved
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Wed, 22 Jul 92 15:37:02 GMT

In article <BrrztE.J4u@well.sf.ca.us> metares@well.sf.ca.us (Tom Van Flandern) writes:

>     After 25 messages in three days on the Twins Paradox, the silence over
>the past few days has been deafening. 

Perhaps because those who have enough skill to become really interested
in your version of the Twin Paradox already worked it out in the last
go-around.  Not that I mean any disrespect to this version.  But I wasted 3
hours last week working through all sorts of variations on the Twin
Paradox with some mathematician colleagues last week, so I'm twinned
out.  

Just in case it ain't abundantly clear to all those lurkers out there -
the Twin "Paradox" is not a paradox, just an amusing puzzle.

Newsgroups: sci.physics
From: met48546@uxa.cso.uiuc.edu (Marc E. Talbot)
Subject: Re: Defining Photons
Organization: University of Illinois at Urbana
Date: Mon, 27 Jul 1992 00:27:44 GMT
Keywords: Relating photons E=MC^2 criticism

snarfy@cruzio.santa-cruz.ca.us writes:


>In Messa:ge-ID:  <9935@sun13.scri.fsu.edu>  J.  A.  Carr  quotes  me  and
>responds :


>>>      Einstein,postulated that a photon has no  ``rest''
>>>      mass.   We  are  faced  ,then,  with  the  task of relating these
>>>      theoretical ``particles'' that do not have a rest masses  to  the
>>>      equation E=Mc^2 since it is assumed that M represents a rest mass

	[arguments about equations deleted  ]

>       Your  criticism is noted and forwarded to my sources.  However my
>       personal evaluation is that you are missing the point.  When  the
>       word  ``particle''  is both applied to that which has no mass and
>       to that which does have mass,  we  must  seriously  question  the
>       choice of words used, for the sake of clarity ,if nothing else .

>        We  are  not here trying to ``apply'' the equatiom E=Mc^2 to the
>       photon. The stated purpose and idea  is  to  ``relate''  massless
>       ``particles''  to  the  massive  ones  in the M of E= Mc^2 . If a
>       photon has E and E has some relationship to M via E=Mc^2 (or  E^2
>       =  m^2c^4  + p^2c^2) then there must some ``relationship'' that a
>       photon  has  to  M  that  can  be  expressed  or  measured.   The
>       expression  E=pc  contains no reference to M so that's one reason
>       E=Mc^2 was used. The other reason is that we want E on  one  side
>       of the equals sign and not E^2.

>>I find it odd that someone can spend a lot of time working on such a
>>document that was posted here and never take the time to read enough
>>of Einstein to know the actual equations he used.

>       If you are a college professor , the taxpayers  or  students  pay

	[ personal slam deleted ]

>       would  be  more accurately described as a ``phenomena'' given the
>       difficulty  you  have  manipulating  it  the  same   way   as   a
>       ``particle''   mathematically.  (multiplying  by  zero  ,for  one
>       thing).

>      I find it odd that you have a job.

>          Jim Ostrowski

There IS in fact another term used for describing the phenomenon of light,
ie waves.  Unfortunately, it falls short of completely describing light and
its interaction with matter.  What we get left with is a description of
light which says that it behaves like both a particle AND a wave. 
Read this as:  it's not a particle, it's not a wave.  I think what you
are arguing is chiefly semantics.  For a far better explaination, see
vol 1 of the Feynman Lectures series (hey, I'm just an undergrad, and
he was a Nobel laureate).  What I think you'll find is that we just
don't have any everyday, intuitive examples to compare it to.  It
doesn't behave like a baseball, and it doesn't behave like a water wave.
All we can really say is that it behaves like something else.

Newsgroups: sci.physics