HDTenEightyP/NetNews huggingface dataset:
From: daryl@oracorp.com (Daryl McCullough)
Subject: Thermo question for you
Organization: ORA Corporation
Date: Mon, 5 Oct 1992 17:44:26 GMT

In article <1992Oct1.223858.10776@hellgate.utah.edu>,
tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman) writes:

>There are two spheres in the following area divided into "macrostates" and
>"microstates":
>
>-------------
>|     |     |
>|     |     |
>|     |     |
>-------------
>|     |o    |
>|     |     |
>|     |   o |
>-------------
>
>The bottom right corner is a special state, the others are not interesting.
>The probability of it being in this state is 1/16... what is its entropy?

In statistical mechanics the entropy of a macroscopic state is given
by k log W, where k is Boltzman's constant, and W is the number of
microscopic states that give rise to the same macroscopic state.
Before you can determine the entropy of a system, you need to know
what a (sufficiently) complete microscopic description of the state
is, and what a complete macroscopic description of the state is.
Usually, in classical statistical mechanics the microscopic state is
determined by giving the positions and momenta (to a certain
accuracy). The macroscopic state is given by the total energy, volume,
and number of particles.

In your case, you haven't really said what a complete microscopic and
macroscopic description is. Just for definiteness, I will assume that
the particles are distinguishable, and that a complete microscopic
description consists of saying for each sphere in which of the four
boxes the sphere can be found. Since you declared the lower right box
"special", I will assume that the macroscopic description consists
simply of giving the total number of spheres in the lower right box,
and the total number of spheres in all other boxes (we don't care
which box a sphere is in, as long as we know that it is not in the
lower right box).

Given all this, there is only one possible state consistent with the
macroscopic state "Two spheres in lower right, none elsewhere". So the
entropy is zero.

>Now consider the system at some time later:
>
>-------------
>|     |  o  |
>|     |     |
>|     |     |
>-------------
>|     |o    |
>|     |     |
>|     |     |
>-------------
>
>What is the entropy of this, and why?

The macroscopic state is given by "One sphere in lower right, one
elsewhere". Assuming distinguishable spheres, there are 6 possible
microscopic states. The first sphere can be in the lower right, while
the second sphere can be in one of three boxes, or the second sphere
can be in the lower right, while the first is in one of three boxes.
Thus the entropy is k log 6.

If instead you assume that the spheres are indistinguishable, then the
number of possible microscopic states is 3---one sphere is in the lower
right, while one sphere is in one of the 3 other boxes.

Daryl McCullough
ORA Corp.
Ithaca, NY

Newsgroups: sci.physics
From: sichase@csa3.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Top 10 List (was Re: Another Cute Math Joke)
Date: 4 Oct 1992 15:31 PST
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: world
NNTP-Posting-Host: 128.3.254.198
News-Software: VAX/VMS VNEWS 1.41    

In article <1992Oct3.165309.20134@morrow.stanford.edu>, COWAN@ssrl01.slac.stanford.edu (Paul L. Cowan) writes...
>In <1992Oct2.123755.22685@ulrik.uio.no> jarleb@athena.uio.no writes:
> 
>:        TOP TEN EXCUSES FOR NOT DOING THE MATH HOMEWORK
> 
>These are great! Does there exist a similar list for physics? 
>After all this is sci.physics. If there is one (in the FAQ?) please excuse
>this modest attempt: 
> 
>        TOP TEN EXCUSES FOR NOT DOING THE *PHYSICS* HOMEWORK

Which reminds me of a list that I compiled some months ago:"

	 TOP TEN THINGS PHYSICISTS DO

10.  	Argue about how best to trigger the oscilloscope
9.   	Play with slinkys
8.	Write software that will never be used again
7.	Calculate overhead for Federal grant proposals
6.	File unread preprints
5.	Try to teach physics to spouse
4.	Reboot
3.	Listen to Bill Wattenburg, late night on KGO	
2.	Complain about the compiler

And the #1 Think that Physicists Do:

1.	Calculate Chi-Squared

-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
From: sichase@csa1.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: LARSONIAN Physics and Astronomy
Date: 29 Sep 1992 13:43 PST
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: world
NNTP-Posting-Host: 128.3.254.196
Keywords: Larson, Beckmann
News-Software: VAX/VMS VNEWS 1.41    

In article <1992Sep29.070639.25909@midway.uchicago.edu>, mfm0@midway.uchicago.edu writes...

>of a gravity well?  What do we know about the fundamantal constants
>outside of the earth's and sun's G field?  But questions like this are 
>simply a way of learning more about the universe, and getting some
>intelligent discourse going.

We know a surprising amount about questions of this sort, as the result
of astronomical observation of distant galaxies.  This allows us to 
sample atomic properties (which depend on the electron charge, mass, and
the speed of light) at large distances from us and in the distant past.

So far as we are able to measure, the speed of light is the same
everywhere, and has been for billions of years.  Ditto for the electron
mass and charge.  I apologize for the lack of hard numbers.  But my
personal library is at home, and I am posting from the office.  There
are too many unscrupulous grad students and post docs wandering about to 
keep my precious darlings on the office shelf.

Then there is the Dirac large numbers hypothesis, which implies that G
itself changes with time - for which there is no evidence other than the
(vaguely) theoretical arguments of Dirac.

-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
Newsgroups: sci.physics,sci.math
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: How do you draw a straight line?
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Tue, 6 Oct 92 17:25:53 GMT

In article <1992Oct6.121036.15029@sei.cmu.edu> firth@sei.cmu.edu (Robert Firth) writes:
>In article <1992Oct6.030213.20215@galois.mit.edu> jbaez@riesz.mit.edu (John C. Baez) writes:
>
>>The compass is nice because it works straight from the definition of a
>>circle, while a ruler, as you note, is not so nice since it does not
>>work from the definition of a straight line as the shortest path between
>>two points.  However, there is a machine that has been built which draws
>>straight lines "by definition."  Alas, I forget how it works.
>
>Gee, we did this in school - don't they do it any more?  You draw a
>straight line by taking a thread covered in chalk dust, and stretching
>it between the two points.  Then snap the taut thread against the
>blackboard to get a chalk line.  That "machine" does follow from the
>Euclidean definition.

Okay, everyone is pointing this out, which is good, but I had in mind an
infinitely more complex apparatus that I saw in a book somewhere.  The
used to make all sorts of mechanical gizmos with wheels and such that
allowed one to draw various mathematical curves, and I think someone
designed one to draw a straight line.  Admittedly silly, but fun.  

In short, my rules are: make it out of solid hunks of steel (no steel wires).
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Space-time IS a semi-Riemannian manifold (?)
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Mon, 5 Oct 92 05:28:20 GMT

matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:

>No. It isn't unanswerable. If the word "existence" has any meaning at a
>all, then time exists. I am amazed at all this talk of time being
>"defined" by clocks, at people who speak of spacetime as a "model", at
>talk of "temporal" phenomena by people who doubt that time exists.
>Spacetime is not "modelled" by semi-riemannian manifolds, it IS such a
>manifold.

I am awed by your certainty.  Many of the best researchers in quantum
gravity would dearly like to know whether spacetime is a
semi-riemannian manifold.  What info do you have that they don't? 
Barring seances with Einstein's ghost, I would prefer to say
"spacetime is well modelled by a semi-riemannian manifold on
sufficiently large distance scales."  

On the other hand, I agree that the idea of time being "defined" by
clocks is essentially a cop-out unless one has a good theory of what
counts as a clock and why cesium clocks are regarded as "better"
clocks than baloney sandwiches.  (In other words, although I am of an
operationalist bent, I don't think one can weasel out of the issue of
time simply by defining time to be that which is measured by that
which we build to measure time.)

As for whether time "exists," until someone lays out their precise
definition of "exists" I will use my everyday sloppy one, according to
which time, numbers, baloney sandwiches and societies all exist, even
though they are very different sorts of things.
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: RESONANT AIR COLUMN EXPERIMENT
Date: 25 Sep 92 21:42:50 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Organization: SCRI, Florida State University

In article <246@mindlink.bc.ca> Gordon_Wong@mindlink.bc.ca (Gordon Wong) writes:
>In the classic resonant air column experiment where a tuning fork is struck
>over a graduated cylinder, the tube length is varied in some matter, to
>cause a reinforcement of the sound of the tuning fork. These reinforcements
>occur at L = WL/4 (fundamental); L = 3/4*WL (1st overtone); L = 5/4*WL
>(2nd overtone); etc ... [Note: L = length of column; WL = wavelength]
>Supposedly, the idea of this experiment is to measure L, then use that
>measurement to determine the wavelength, then to calculate an accurate value
>for the speed of sound.

First, you must worry about the end correction, because the air motion at 
the end of a tube does not correspond to the idealization of the boundary 
condition used in deriving the formula relating L and \lambda. 

The end correction causes the "effective length" of the tube to be 
less than its actual length by about 0.6 of a tube diameter. 

Reference: Home Experiment 5.15 on page 257-8 of "Waves: Berkeley Physics 
Course - volume 3" by Frank S. Crawford Jr.  (You might find HE 5.16 
and 5.18 of interest as well.)  His description of the Helmholtz 
resonator -- aka Whiskey-bottle resonator -- Home Experiment 4.15 
on page 218-9 is excellent also.  

Since it is easy to get different diameter cardboard tubes (e.g. 
wrapping paper sometimes comes on large diameter tubes), you 
can test this formula by comparing lengths for same tuning 
fork and different diameter tubes.  

There are many ingenious problems suggested in this book, including 
one about the phase sensitivity of your brain-plus-two-ears system 
(Home Experiment 5.17) and some other nice ones for the bathtub. 

>My question: Which (the fundamental, the 1st overtone, or the 2nd overtone)
>would yield the more accurate value for the wavelength; or does it matter?

Good question.  Your experiment should help you answer it. 

My question: it is fall, so the air temperature is changing.  Is this 
measurement accurate enough to sense the change in the speed of sound 
with changing air temperature?

--
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)
Newsgroups: sci.physics
From: ramsay@unixg.ubc.ca (Keith Ramsay)
Subject: Re: Defining local, causal etc., was: Hidden variable theories
Organization: University of British Columbia, Vancouver, B.C., Canada
Date: Sat, 3 Oct 1992 02:09:57 GMT

In article <1992Sep29.170356.13002@newshost.lanl.gov> 
jlg@cochiti.lanl.gov (Jim Giles) writes:
|It is not possible to distinguish between wavefunctions that are
|hypothetical entities and  wavefunctions which are real objects.
|Not empirically.  Therefore, their introduction violates Occam's
|razor. 

In article <1992Oct2.013142.25298@unixg.ubc.ca>, 
ramsay@unixg.ubc.ca (Keith Ramsay) writes:
| How do you distinguish between "hypothetical entities" and "real
| objects" in any other case?

In article <1992Oct2.193606.995@newshost.lanl.gov> 
jlg@cochiti.lanl.gov (Jim Giles) writes:
|If you can show me an experiment which can be (at least hypothetically)
|performed which yields a different result if "wavefunction collapse"
|is reified than it does if it is not even mentioned, then I'll consider
|the question of the existence of such an event.

This is not what I asked. I was asking a more basic question: if you,
sometimes, distinguish between "hypothetical entities" and "real
objects", then how do you do it at all?  Most of us regard at least
some of the entities in physics as "real objects". Why? Look at cases
other than that of "wave functions", and explain what the difference
is. For example, in what way are you saying quantum waves are
different from atoms or chairs or tables, which most of us regard as
"real" in the ordinary sense of the word?

If you're not claiming any difference, then you should admit that you
are arguing for treating ALL objects as "hypothetical" (which can be a
perfectly respectable philosophy, by the way, a form of
"phenomenalism"), and not claim it as something special about quantum
mechanics. Where does "reification" "yield a different result" at all?

>  The fact is, QM works
>*without* "collapse" even being mentioned.

The question of "wave collapse" is not the one I was asking about. In
the bit I quoted first, you only mentioned the wave (functions). You
can do away with "collapse", but failing to mention the waves
themselves at all is somewhat trickier, isn't it, eh?

I do have some sympathy with abolishing "collapse", as one does in the
"Many Worlds" interpretation, given that the theory works without it,
and there seems to be no non-arbitrary point at which to say that the
"collapse" has occurred. But that is different from abolishing mention
of waves entirely.

Keith Ramsay
ramsay@unixg.ubc.ca
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: invention of time [not]
Date: 28 Sep 92 22:42:15 GMT
Organization: Rutgers Univ., New Brunswick, N.J.


 snodgras@cyber.net (John E. Snodgrass) wrote:
> The commonly expressed view is otherwise, i.e. that
>black holes contain singularities, which cannot be categorized
>as 'matter'.

  No, the commonly expressed view is that the singularity is an
artifact of trying to use the theory in a regime where its
applicability breaks down. 

>       My suggestion is to think of everything as involving
>physical systems, and never to geometrize or probabilize. Try it,
>and you'll find you can see plenty of alternatives.

oh.
and what would they be?

>       Neutrinos may correspond to some segment of the spectrum
>in their velocity. How close their reception was in terms of the
>event (which itself is a somwhat drawn out affair) or whether
>they actually came from this supernovae (since the affected
>experiments did not involve directional receivers or other ways of
>telling the source of the neutrinos) seem relevent questions.

Questions to which there are easy answers, if you look it up.
Supernovae are indeed drawn-out affairs, but the neutrino emission
is not.  It occurs on a timescale of 3-10 sec.  In fact, the
neutrinos emitted by SN 1987A were detected over a 12-sec period
at Kamiokande II (11 events) and a 6-sec period at IMB (8 events).
These detectors are water Cerenkov-light tanks and *are* directionally
sensitive, but do not discriminate direction well for neutrinos.
However, such a large excess of neutrinos were observed that an
astounding coincidence is required for them to have come from any
other source.  The neutrinos were observed 18 hours before the
supernova was spotted visually.  (Reference: W.C.W. Williams, Nuclear
and Particle Physics pp. 364-366)

You might try this little problem: 
  "Suppose that the neutrinos emitted by the supernova SN1987A were
all generated and left the core in a period of one second.  A large 
fraction of the twenty neutrinos detected 160,000 years later were
all observed in a period of 2 sec, with a mean energy of about 8
MeV.  Make a rough estimate of an upper limit on the neutrino mass."
(this is Williams's problem 12.18)
Xref: sparky sci.physics:15768 sci.engr:2085 sci.chem:3786 sci.materials:739
From: borra@astro.phy.ulaval.ca (Ermanno Borra)
Newsgroups: sci.physics,sci.engr,sci.chem,sci.materials
Subject: Question: How to remove oxide from gallium?
Date: 1 Oct 92 19:58:41 GMT
Organization: Universite Laval, Ste-Foy, Quebec (Canada)
Originator: borra@astro


	I wonder whether somebody can suggest solutions to my 
problem. I pour either liquid gallium or a Ga-In eutectic in a container, 
and find that the surface (several feet across) is covered with a thick 
layer of oxide scum.  The problem occurs during stirring, that occurs 
just when I pour Ga After pouring, I do not stir the liquid again.
 I would like to get rid of the opaque oxide scum and get a shiny 
optical quality surface. Although it is in principle possible to work in 
an inert atmosphere and avoid the oxide, it is difficult to do so in 
practice, because of our setup. I know that, in an oxygen atmosphere, 
an oxide layer forms instantly but this is OK since the oxide layer that 
forms on an undisturbed surface is very thin and protects the Ga  
below from oxidation (like it does with Al). My real problem occurs at 
the moment of pouring since the liquid is stirred and we get too much 
thick messy oxide. Ideally, I would like to remove the oxide with 
chemical means, get a clean Ga surface that can be oxidized with the 
very thin layer of oxide that naturally forms on an undisturbed 
surface. 
I have tried to expose the oxide to HCl vapors. The surface becomes 
more reflective but its quality is not good enough for my application 
(using it as a an optical mirror).
	
If you have a suggestion, please email at borra@phy.ulaval.ca

				  Thanks,
E.F. Borra
Newsgroups: sci.physics
From: sichase@csa1.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Question about electron spin
Date: 28 Sep 1992 10:27 PST
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: world
NNTP-Posting-Host: 128.3.254.196
News-Software: VAX/VMS VNEWS 1.41    

In article <10910@sun13.scri.fsu.edu>, jac@ds8.scri.fsu.edu (Jim Carr) writes...
> 
>The answer is identical to the answer you get for three Polaroid sheets 
>laid at 120-degree angles on top of an sheet that defines the original 
>polarization.  Surely you have seen (or done, find some friends with 
>Polaroid sunglasses) the experiment where you have crossed (90 degree) 
>polarizers and then insert one between them at 45 degrees and see it 
>go from black to (dim) light.  Same thing with electrons. 

This experiment had a very profound influence on me, when I first saw it
as an undergrad.  I'm not entirely sure why.  I understood, mathematically,
why it *should* work, but was still struck with wonder that it *really did*
work.  I guess that I am easily amused.

-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
Newsgroups: sci.physics,sci.math
From: rags@triples.math.mcgill.ca (Robert A. G. Seely)
Subject: Re: Mattel on women
Keywords: Targetting females once again.
Organization: Dept Of Mathematics and Statistics
Date: Mon, 5 Oct 92 19:24:33 GMT


One thing this thread makes clear is that there are lots of folk out there
who won't object to Mattel's message - even those who ought to know better
(IMO)...  I had not originally planned to act on this, but now I reckon that
we (ie those who share the opinion that women-in-math bashing is not to be
encouraged) perhaps ought to make sure our view is recognised by Mattel -
and others - and so will send a polite but firm protest as the original
poster suggests.  If you agree, maybe the time spent to that end is more
fruitful than another posting to this thread...

- rags
Newsgroups: sci.physics,sci.astro,sci.math,sci.philosophy.tech
From: hporopudas@tnclus.tele.nokia.fi
Subject: Re: STRUCTURE OF TIME (at numerous requests)
Organization: Nokia Telecommunications.
Date: Mon, 28 Sep 1992 07:10:53 GMT


In article <1992Sep24.102014.1@tnclus.tele.nokia.fi>,
hporopudas@tnclus.tele.nokia.fi writes:
> Hi !
>
>    Due to many E-Mail requests I put this "Structure of Time" message and
>  related messages here again. In colour photographs hanna_maria1.gif
>  (01/03)-(03/03) and hanna_maria2.gif (01/04)-(04/04) some of Hanna-Maria's
>  drawings are also seen (these .gif are for example in
>  alt.binaries.pictures.misc, and unfortunately they slipped also in
>  sci.physics and sci.astro).
>
>      Hannu.  (24.09.1992)
>

    ...deleted text part...


     In the end of this conversation I would like to remind to all readers
   that I have tried to be only as accurate clerk in this matter as possible.
     And because this inhuman and hostile environment of science to amateurs
   I have some doubts that will Hanna-Maria ever become scientist when
   she grows up. This kind of hostile and unhuman environment could injure
   her seriously.


          Hannu.

     "I think that atheistic scientists are fully reponsible for ordinary
   peoples sufferings in all over the world, when they have instructed them
   to reject God's good doctirine given in The Holy Bible. This doctrine
   teaches ordinary people to respect good. Now this kind of respection
   does not exist and good peoples who respect good are considered to be mads.
   You all "wise scientists" should know that this means only one thing,
   namely that all kind of evil will be in full power in all around the world."


Newsgroups: sci.physics
From: daryl@oracorp.com (Daryl McCullough)
Subject: Re: Defining local, causal etc., was: Hidden variable theories
Organization: ORA Corporation
Date: Fri, 25 Sep 1992 12:36:30 GMT

In article <1992Sep23.191356.1349@galois.mit.edu>, jbaez@riesz.mit.edu
(John C. Baez) writes:

>Well, part of the point is that there is no wavefunction of the sort
>Psi(R,t) in quantum field theory, quantum field theory being what you
>get when you try to combine quantum mechanics and relativity.  You
>will have to refine your arguments to take this into account because
>nobody claims that quantum mechanics with single-particle wavefunctions
>Psi(R,t) is suitable for relativistic situations.

I'm not sure that I agree. Quantum field theory still gives a
probability amplitude for the process of detecting a particle in a
given neighborhood. I think it is Psi(x) |Phi>, where Psi(x) is now an
operator (a particle annihilation operator) and |Phi> is the state of
the system (in general, with an indefinite number of particles).

What is different about quantum field theory is that because of the
possibility of particle creation, multiple simultaneous detections
cannot be ruled out (although the probability can be made small).

Daryl McCullough
ORA Corp.
Ithaca, NY