HDTenEightyP/NetNews huggingface dataset:
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Entropy
Date: 27 Aug 92 17:36:00 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

>Gibbs vs Boltzmann Entropies
>E T Janes (1965)
>Reprinted in:
>E T Janes: Papers of Probability, Statistics and Statistical Physics
>Ed: R D Rosenkratz
>Kluwer Academic/Pallas paperbacks
>ISBN 0-7923-0213-3

FYI, if you're going to look it up, it's E.T. Jaynes with a "y."  This
is a good book to look at if you wan to try to really understand
what is going on with all those F's and G's.

My undergrad stat phys book derives the thermodynamic relation
F = E - TS from  S = k ln Omega  and  F = -kT ln Z.  (It's F. Mandl,
_Statistical Physics_, Wiley 1988, pp 61-63) - a pretty good first
book, I think, firmer than Little Reif but not as dense or
all-encompassing as Big Reif. 

Mandl finds S = -k sum_i (p_i ln p_i)    [where i labels microstates]

and uses the Boltzmann distribution p_i = exp( - E_i / kT) / Z

and of course E = sum_i (p_i E_i)     [really the mean E - OK if N is large]

to get F = E - TS, the usual thermo definition.


By the way Little Reif is the canonical name for _Statistical Physics_
(McGraw-Hill, 1967) which is vol. 5 of the Berkeley Physics Series,
and Big Reif is _Fundamentals of Statistical and Thermal Physics_
(McGraw-Hill, 1965).

As per canonical physicist-speak, "fundamentals" actually means it's
more complicated.
Organization: Mechanical Engineering, Carnegie Mellon, Pittsburgh, PA
Newsgroups: sci.physics
Date: Wed, 26 Aug 1992 13:07:46 -0400 
From: Jonathan Wickert <jw54+@andrew.cmu.edu>
Subject: Concern over radon levels?



I'm in the process of buying a house in southwestern Pennsylvania.  As
part of the home inspection, I had a radon test done by one of these
companies that does radon testing for a living.  It involved placing two
canisters in the basement, and one in the living room.  The canisters
are removed after 3 days of exposure, and then sent to a central state
licensed lab.

The test revealed levels of 4.2, 5.5, and 7.6 picocuries/liter in the
areas tested.  According to guidelines established by the EPA and the
Center for Disease Control, a continuous exposure of 4 pCi/l is used as
a guideline to indicate when some corrective action should be taken.

My questions are

1.  Are these levels sufficently high to be of concern?
2.  How common is it to have such radon levels in this geographical area?

Thanks in advance,

Jon
From: clarke@acme.ucf.edu (Thomas Clarke)
Newsgroups: sci.physics
Subject: Re: fluxgate compasses
Date: 3 Sep 92 15:34:13 GMT
Article-I.D.: cs.1992Sep3.153413.22278
Organization: University of Central Florida

In article <1992Aug31.223050.27166@voder.nsc.com> pad@galaxy.nsc.com (Paul  
Denny x8349) writes:
> I am interested in finding out how fluxgate compasses work. in 
> particular I should like to understand the means by which they
> sense the direction of a stationary magnetic field - I am familiar
> with hall probes and their operation but this one has me stumped.
> Any replies or literature pointers can be emailed - I will summarise
> if there is any interest
> 
> Many thanks - Paul 

Here goes.  Fluxgate compasses depend on the nonlinearity
of ferromagnetic materials.  The Radio Schack fluxgate compass, which
I have dissected and examined the circuit diagram, uses a toroidal
ferrite core and coils to sense the Earth's magnetic field.

A coil is wrapped around the toroid, and two Helmholtz like coils 
at right angles surround the toroid.  The toroidal coil is energized 
by an AC wave at several thousand hertz.

By well known properties of toroidal coils, ideally no signal
should be induced in the Helmholtz coils.  
When an external magnetic field is present, things are not ideal,
however.   In particular, the non-linear B-H curve of the ferrite 
"breaks the symmetry" so  that some of the AC appears in the H-coils.

An external circuit amplifies this AC and turns it into DC which
is fed back into the H-coil so that the magnetic field at the position
of the toroid is cancelled, minimizing the AC.

The two crossed axes of the H-coils then give two DC signals which 
are proportional to the magnetic fields along their axes.  For the
Earth's magnetic field, these and a little trig, give the direction
of magnetic North.

--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu
From: ted@physics20 (Emory F. Bunn)
Newsgroups: sci.physics
Subject: Re: Satellite spying
Date: 25 Aug 1992 23:34:53 GMT
Organization: /etc/organization
Distribution: world
NNTP-Posting-Host: physics20.berkeley.edu

In article <2599@news.cerf.net> jcbhrb@nic.cerf.net (Jacob Hirbawi) writes:
>In article <17chpmINNma3@agate.berkeley.edu> 
>ted@physics3 (Emory F. Bunn) writes:

(Back-of-envelope calculation of spy satellite resolution deleted.
Result was:)
>>     4 x 10-7 radians = 0.08 arc-seconds.

(Suggested explanation of why that seems too good to be true:)

>Perhaps they're using a different wavelength !

To improve the resolution, you'd need to go to shorter wavelengths.
That is, you'd need to go into the ultraviolet  (or even further, to
X-rays or gamma-rays).  But there are big 
problems with this:  Atmospheric transmission is low in the UV;
good optics are difficult to make; and there's not much UV around
to take pictures with.  So I don't think that is the explanation.

-ted
From: forman@bcsaic.boeing.com (David Forman)
Newsgroups: sci.physics
Subject: Re: Are Your Light Bulbs Radioactive?
Keywords: thorium, promethium
Date: 26 Aug 92 03:39:01 GMT
Distribution: na
Organization: Boeing Computer Services AI Center, Seattle

I think the element you want to worry about is thorium.  It's
radioactive, and tungsten filaments in electric bulbs are "thoriated"
to increase efficiency and retard disintegration...  I'm not sure
what kind of radiation you get from thorium, but it's probably
nanorems anyway..

--
Keith Michaels       Boeing Computer Service.
krm@sdc.boeing.com   Seattle, WA.
Disclaimer: Whaddyamean?Ineversaidthatyoucan'tproveanythinghe'slying!!!
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: quantization of angular momentum
Date: 1 Sep 92 18:52:33 GMT
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: na
Reply-To: sichase@csa2.lbl.gov
NNTP-Posting-Host: 128.3.254.197
News-Software: VAX/VMS VNEWS 1.3-4   

In article <TK.92Aug31202517@wheat-chex.ai.mit.edu>, tk@ai.mit.edu (Tom Knight) writes...
>I'd like to understand the quantization of angular momentum better.
>On the one hand, we are told that L is quantized, but we (naively)
>recall that L = r x p, and note that neither the position nor the
>momentum is quantized; presumably, the error or complexity lies in the
>classical definition of the angular momentum, and if we had only
>turned these into operators on the wave function "it would all be
>clear."  Perhaps that's sufficient for some of you, but I'd like a
>little better insight.  Maybe I'm just asking for insight into
>something which is intrinsically not amenable to insight.  If so,
>perhaps that will be some consolation.  Thanks.

L is not quantized under all circumstances.  For a free particle, 
none of r,p, and L are quantized.  For a bound state, L and p are quantized.

Which case is confusing you?

-Scott
--------------------
Scott I. Chase			"The question seems to be of such a character
SICHASE@CSA2.LBL.GOV		that if I should come to life after my death
				and some mathematician were to tell me that it
				had been definitely settled, I think I would
				immediately drop dead again."      - Vandiver
Xref: sparky sci.physics:13968 alt.sex:28189
From: jfreter@triton.unm.edu (The Myth)
Newsgroups: sci.physics,alt.sex
Subject: Re: BAROMETERS (was Re: Subject?)
Date: 2 Sep 92 15:21:01 GMT
Distribution: na
Organization: University of New Mexico, Albuquerque

In article <ZOWIE.92Sep1122151@daedalus.stanford.edu> zowie@banneker.stanford.edu writes:
>This whole thread reminds me of the age-old physics exam question:
>
>You are taken to a large, impressive-looking office building.  You may
>wander the building and its environs at will <etc. etc.> You are given
>an accurate barometer.  Your task is to determine the height of the
>building.
>
>Name at least six ways to accomplish this task. [before breakfast! ;-]

1) go to the building superintendant.  Tel him (her?), "I will give this
barometer to you if you tell me how high the building is."

2) climb to the top of the building.  Throw the barometer off and time how
long it takes to hit the ground (really you should drop it). y=.5*g*t**2.

3) pace a certain distance out from the building.  Put the barometer on
the ground.  Measure the height of the barometer.  Measure the angle between
the ground and the line connecting the tops of both.  Use Trig to calculate
the height.

4) tie a rope to the barometer and lower it off of the top of the building.
mark the height of the building on the rope.  measure the rope.
`
5) As above, but swing the barometer in pendulum fashion.

6) Measure air pressure at the bottom and at the top.  find the density
of air as a function of temperature and elevation.  measure the temperature
at top and bottom.  Calculate the pressure.

7) Build an adjustable catapault (variable launch speeds and angles).  put
the barometer in the catapault and launch towards building.  Repeat until
the barometer just clears the top.  use the launch velocity and the distance
from the building to calculate the height.

More?
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: FTL
Date: 29 Aug 92 15:24:21 GMT
Article-I.D.: husc8.mcirvin.715101861
 <17mel5INNc1n@agate.berkeley.edu> <mcirvin.715053036@husc8> <mcirvin.715057081@husc8> <mcirvin.715059853@husc8>

Oh, no, I'm responding to my own post AGAIN.  I'll shut up after this one,
I promise.  The same prayer to the telephone deity applies.

mcirvin@husc8.harvard.edu (Mcirvin) writes:

>In non-covariant PT the process looks like this:

>                     ^ 
>                    / \   
>                   /   \ 
>                  /     \
>                 v       ^  
>                /         \  
>               /           \  
>              *             *  

>If the distance between the asterisks
>is d, then the process takes a time t > d/(2c).

A couple of points:  First, it's the *wave function* that has to obey
the laws of motion in this formulation.  So if I'm going to talk about
particle paths, they ought to be the same paths that occur in the path
integral one does when one pretends that this is a single-particle
theory: namely, the paths I mentioned before, in which the particles are
in "velocity eigenstates" and travel exactly at c.  This process then
takes exactly t = d/(2c).  Also, the paths can zigzag backward and forward
in arbitrarily complicated ways, so it could take less time:

            /\
           /  \/\/\
          /        \/\ 
         /            \
        *              *

and the like.  Neither modification ruins the argument.  If the process
is the one I just drew, and all the lines go at 45 degrees, you still have  
no idea whether either the "creator" or the "detector" created extra
particle-antiparticle pairs, or whether the detector created a real
antiparticle instead of detecting a virtual particle, until the asterisk
on the right is in your past light cone.

-- 
Matt McIrvin, Cambridge, Massachusetts, USA 
Newsgroups: sci.physics
From: scienger@ecr.mu.OZ.AU (Christopher_Robert INNES)
Subject: Gravitational lenses
Organization: Dept. Of Engineering Computer Resources, Uni. Of Melbourne
Date: Mon, 31 Aug 1992 03:24:43 GMT



Greetings,
I'm currently reading a book called `The Dark Matter' which is 
dicussing dark matter and methods of detecting it. One of the methods mentioned
was using the gravitational lens effect. If I understand it correctly
foreground galaxies , due to their mass and therefore gravitational field ,
'bend' the light of a background galaxy , which is behind the foreground
galaxy , due to einstein's general theory of relativity. I was just wondering
if gravitational lensing has been observed by astronomers. 

Also what is the current state of dark matter theory? I mean has anymore
evidence in the last few years come to light?

( Knowing my luck this whole topic has probably just been discussed and 
everyone will want to kill me when they read this )

--------------------------------------------------------------------------------

scienger@ecr.mu.oz.au
Chilin' with the homies
From: bwood@diva.Berkeley.EDU (Blake Philip Wood)
Newsgroups: sci.physics
Subject: Re: ELECTRON HELIX : ITS POWER AND POSSIBLITIES
Date: 3 Sep 1992 14:19:56 GMT
Organization: /etc/organizaton
NNTP-Posting-Host: diva.berkeley.edu

In article <1992Sep2.150717.8836@murdoch.acc.Virginia.EDU> gsh7w@fermi.clas.Virginia.EDU (Greg Hennessy) writes:
>In article <12950073@hpspdla.spd.HP.COM> ric@hpspdla.spd.HP.COM (Ric
>Peregrino) writes: 
>#You can't accelerate with a magnetic field; F = Q V x B.
>
>Fermi acceleration.
>
>-Greg Hennessy, University of Virginia

The role of the B-field in Fermi acceleration is simply to return
the particle to a region where it can be repeatedly accelerated
by E-fields.  See Lichtenberg and Lieberman's book "Regular and 
Stochastic Motion" (1983) for more info.  Their second edition,
entitled "Regular and Chaotic Motion" just hit the shelves last 
month.



-- 
                 Blake P. Wood - bpw@ctxsys.lanl.gov (505) 665-6524
                 Group P-1, MS-E526, LANL, Los Alamos, NM  87545
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Differential Geometry and Physics, was: Re: Misner et al.
Date: 3 Sep 92 22:37:31 GMT
Article-I.D.: husc8.mcirvin.715559851

toon@moene.indiv.nluug.nl (Toon Moene) writes:

>I took a course in differential geometry at the same time I took a course  
>in GR based on Weinberg's book. Note: The book would be half as thick if  
>he just used the most basic things from differential geometry - what a  
>waste ...

I did exactly the same thing.

It's a fairly well-written book submerged in a sea of indices.  I
learned GR from it and then re-learned it when the differential
geometry class got around to Riemannian geometry the next semester.
It seemed so much simpler the second time around-- and stuff that
is nearly unintelligible in Weinberg's book because of the index
notation, like tetrads and differential forms, became blindingly
clear. 

>I've never understood what's wrong with DG so that physicists shouldn't be  
>exposed to it; it turns up in every field in physics sooner or later.

Some physicists possess a prejudice toward expressing everything in
terms of real numbers.  When objects have their numerical components
obscured, it makes them nervous-- there's the feeling that you're no
longer dealing with something physical.  That goes double for things
that don't even have numerical components, like fermion fields. 

-- 
Matt McIrvin, Cambridge, Massachusetts, USA 
Newsgroups: sci.physics,sci.astro,sci.math,sci.philosophy.tech
From: hporopudas@tnclus.tele.nokia.fi
Subject: Re: About my postings (Calendar (NEW) etc.)
Organization: Nokia Telecommunications.
Date: Wed, 2 Sep 1992 08:01:13 GMT


  I would like to comment bwallet@apssgi.nswc.navy.mil (Brad Wallet)'s
  message:


   Can't we ever get rid of these unbusinesslike comments. ?

              Hannu.

Newsgroups: sci.physics
From: phillies@wpi.WPI.EDU (George D. Phillies)
Subject: What's New
Organization: Worcester Polytechnic Institute
Distribution: na
Date: Sat, 29 Aug 1992 18:20:48 GMT

>In  <92234.155924WTU@psuvm.psu.edu>
>>"Janice Smith" <VP.APS@Forsythe.Stanford.EDU>
>>is said to have posted
>>Subject: What's New for August 21, 1992

>>	3. BUT NASA IS PREPARING TO ANSWER "A BASIC BIOLOGICAL QUESTION."
>>Thirty people have worked for over 8 years getting ready for this
>>	Spacelab mission, which will cost about $1B. Biologists the world
>>	over are tingling with anticipation as they await results of the
>>	early September mission to find out "if gravity is essential to
>>	the normal fertilization of frog eggs and the early development
>>	of frogs."  

Developmental biology is a vital field of modern science.  If you 
don't believe me, read a few months of back issues of Science or 
Nature.  However, the focus in modern developmental biology is 
substantially on the genetic control mechanisms that regulate the 
differentiation of cells.  The claim that  "biologists the world
over are tingling with anticipation" is, to put it politely, 
astonishing; it would be interesting to see documentation for this
remarkable claim as made in the above post.

One might better argue that we see here a particularly bad example
of the dark side of biophysics: scientists bringing in line enormously
expensive physical techniques to study questions in which the recipient
community has virtually no interest.  NASA and others have spent
a prolonged time pushing the assertion that the unicity of the
microgravity environment lets one do experiments that can justify their
cost.  The range of such experiments appears to be declining as the
years pass.  For example, the development of capillary electrophoresis
appears to have reduced interest in doing Tiselius (free ) electrophoresis
in zero-g.  Multinuclear NMR appears to have supplanted the utility of 
crystallizing low-molecular-weight proteins under zero-g.  etc.

The legitimate question is at what point you have people pushing
towards an exciting if unclear future, and at what point you have
a welfare program --- a program that affords large groups of scientists,
engineers, and bureacrats generous checks for largely meaningless
work.

George Phillies
phillies@wpi.wpi.edu





Newsgroups: sci.physics
From: dedmunds@selkirk.sfu.ca (Darran Edmundson)
Subject: nonlinear refractive index of liquids?
Organization: Simon Fraser University, Burnaby, B.C., Canada
Date: Thu, 27 Aug 1992 16:53:17 GMT

I'm interested in finding liquids that display a saturable Kerr refractive
index.  This has the form

	n = n_0 + n_2 I / (1+I/I_{sat})

where I_{sat} is the saturation intensity.  If you don't know of any
liquids in particular, how about the names of researchers measuring
the optical properties of liquids.  I've done a decent literature search
but so far to no avail.

Thanks.

-- 

Darran Edmundson
darran@chaos.phys.sfu.ca

Newsgroups: sci.physics,sci.astro,sci.math,sci.philosophy.tech
From: hporopudas@tnclus.tele.nokia.fi
Subject: About my papers (Calendar (NEW), Ancient Times, Surface Algebras, Struc
Organization: Nokia Telecommunications.
Date: Tue, 1 Sep 1992 08:30:44 GMT


 Hi !

     I would like to put one my E-mail comment about my papers here, because
  I consider it significant.

        Hannu.


  P.S. One other experimental possibility (although very uncertain) to find the
       exotic particle called "space potato" is possible from COBE's sky map
       pictures provided that the small scale structure of the Universe is
       steadyly magnified enormously to the largest scale structure of the
       Universe as Universe has uniformly expanded. These spots or spot
       triplets could have someting to do with this although errors in these
       measurements are quite large (let us wait a little better accuracy).
       These spots are possibly also seeds of galaxies and clusters of galaxies.


 Below this comment:


> Dear Sir,
>
>  I would like to comment your E-Mail below:
>
>
  From:	SMTP%"X" 30-AUG-1992 14:16:42.23
>>To:	HPOROPUDAS@tne01.tele.nokia.fi
>>CC:
>>Subj:
>>
>>Date: Sun, 30 Aug 92 07:05:07 EDT
>>Message-Id: <9208301105.AA17915@rosie.mlfarm.com>
  From: X
>>To: HPOROPUDAS@tne01.tele.nokia.fi
>>In-Reply-To: HPOROPUDAS@tne01.tele.nokia.fi's message of Sun Aug 30 12:34:49 +0400
>>
>>HPOROPUDAS@tne01.tele.nokia.fi writes:
>>
>>   Dear Sir,
>>
>>   If I post, I try to do messages as short as possible.
>>
>>Not really.  Your calendars and the musings of your daughter are of
>>very limited interest.  You should post a notice that a new version of
>>your calendar or a new cosmology of space potatoes is AVAILABLE, and
>>give ftp, uucp, or mail instructions for the few readers who might be
>>interested.  With a little net courtesy, you would actually gain more
>>readership instead of alienating the few readers who haven't already
>>put you in kill-files.
>>
  				X
  			    X
>
>    I'am sorry that I could not use this kind of possibility, because I don't
>  have any ftp, uucp where I could put my works.
>    There are also other difficulties, namely this publishing system that
>  our science uses in scientific newspapers. This system does not allow me to
>  publish any of my papers. So this Net was my only possibility.
>    I would like to say that my "Structure of Time" paper is important,
>  because I have pointed there some faults in basic definitions our current
>  physics. One of these important points was the correct definition of mass
>  of base particles and one other point was description of correct nature of
>  anti-matter and explanation of existence of negative masses. And numerous
>  other things which will cause that some parts of our current physics and
>  cosmology must be rewritten.
>
>
>              Regards,
>                      Hannu Poropudas
>
>
>   "Thrown to ignorance peoples give themself to work and employment, and
>    by keeping themselves sensible and learned they stagger without goal
>    like blinds lead by blinds."
>
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: Subject?
Date: 31 Aug 92 17:06:40 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Distribution: na
Organization: SCRI, Florida State University

In article <17mijiINN7de@matt.ksu.ksu.edu> lyn@matt.ksu.ksu.edu (Myself) writes:
>
>    Terminal Velocity- the typing speed at which your keyboard starts to smoke,
>causing you to either A) slow down to just below said velocity, or B) talk to
>rec.pyrotechnics.
>
>	Well, that clears that up. On to other things (like another type of 
>							terminal velocity ;-}  )

Not quite.  Terminal velocity is the maximum speed of a terminal dropped 
from a great height. 

There are other experiments one can do with computers, some of which were 
summarized in an article by Walt Benenson that appeared in the "New 
Scientist" of 6 May 1989, page 68.  They include the Tower of Pisa expt 
with different sized computers, studying the coefficient of friction by 
tipping the table until one slides off, etc.  Most amusing stuff. 

--
J. A. Carr                                    |  "The New Frontier of which I  
jac@gw.scri.fsu.edu                           |  speak is not a set of promises
Florida State University  B-186               |  -- it is a set of challenges."
Supercomputer Computations Research Institute |   John F. Kennedy (15 July 60)