HDTenEightyP/NetNews huggingface dataset:
From: xie@phoenix.Princeton.EDU (Yan-bo Xie)
Subject: Re: Entropy
Originator: news@nimaster
Organization: Princeton University
Date: Thu, 20 Aug 1992 21:12:03 GMT

From article <Aug.20.15.59.36.1992.7531@pilot.njin.net>, by jmgreen@pilot.njin.net (Jim Green):
> 
> My gratitude for the responses to my query re entropy both here and
> email.
> 
> The problem is that standard texts DO NOT provide a very good
> explaination of the equivalance between the Carnot and the statistical
> derivations of entropy.  If any is given at all it is limited to the
> idea that because for two systems S=S1+S2 and W=W1xW2 thus the only
> function which can connect S & W is the ln ie S=klnW.  This is not
> very satisfying to me nor my students.  It is indeed likely that  I
> have missed a good illucidation somewhere and I will check out 
> PWAtkins as has been suggested.  
> 
> There seem to be TWO Reif's.  I don't think that my Reif does the
> deed.  Can Yan-bo Xie be more specific as to which Reif he refers.
> And can someone PLEASE give difinitive titles and publishers to the
> two Reif's, which are sometimes refered to as Big Reif and Little
> Reif.
> 
> This will help a lot.  Thanks.   Jim Green

Sorry if my post is not clear. I mean the book which is less mathmatics
but more physics.  That is Volume V of the UCB undergraduate general physics
series.  That book gives a very clear definition of temperature T
(from statistical physics), and also gives the reason why people
define T in this way.  Also that book shows this T is the same as
the T given by the Carnot machine.

In fact, there may be many other good books about this.  
But this one made me understand the points a little bit.

Yan-Bo Xie

Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: the nature of exclusion
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Fri, 21 Aug 92 16:40:01 GMT

In article <1992Aug18.214628.9544@math.ucla.edu> barry@arnold.math.ucla.edu (Barry Merriman) writes:
>In article <1992Aug14.210429.23650@galois.mit.edu> jbaez@zermelo.mit.edu (John  
>C. Baez) writes:
>> Certainly compressing a gas of fermions is harder than compressing a gas
>> of bosons because of Pauli exclusion.  You can say "I'll try hard to
>> squeeze it down so they all get squished into the same state" -- but
>> even as you squeeze down the position you let your fermions occupy,
>> there's plenty of room in *phase* space
>
>right, but then that implies as I compress in space I expand in
>momentum, which would seem to imply ther temperature goes up. 

No.

>What
>if I simultaneously cool the gas as I spatially compress it, say
>by keeping in in contact with a low T heat reservoir?

You will wind up with the zero-temperature Gibbs state of a
highly compressed bunch of fermions.  This will have the fermions in
states that are as low in energy as possible subject to the Pauli
exclusion principle.  I.e., one fermion in the lowest energy state, one
in the second lowest, etc..   For a highly compressed system some of the
occupied states will have rather high energies.

Recall that temperature is not in general proportional to energy, though
it is for ideal gases.
From: jfw@ksr.com (John F. Woods)
Newsgroups: sci.physics
Subject: Re: Survey
Date: 20 Aug 92 13:36:15 EDT

70253.2621@CompuServe.COM (Chris & Susan Colvin) writes:
>When you die, where will you go?  (in the ground is not a valid answer)

You're a mausoleum salesman, right?

"Life is so much more meaningful if you take the time to hunt down and strangle
 twits who post blather to inappropriate newsgroups." -- Henry Spencer
From: ag3l+@andrew.cmu.edu (Arun K. Gupta)
Newsgroups: sci.physics
Subject: Re: Volume occupation
Date: 16 Aug 92 18:09:22 GMT
Article-I.D.: andrew.keXkdGi00aw=8OgEVs
Organization: Physics, Carnegie Mellon, Pittsburgh, PA


>From: sichase@csa2.lbl.gov (SCOTT I CHASE)
>Subject: Re: Volume occupation (was Re: Vector Bosons?)
>Date: 16 Aug 92 19:40:55 GMT
>
>In article <1992Aug16.013415.3630@cerberus.ulaval.ca>, yergeau@cornu.phy.ulaval.ca (Francois Yergeau) writes...
>>
>>I countered that plain electrostatic interaction must come before that,
>>making the following argument: forget about spin, and solve the good
>>old Schrodinger equation for a hydrogen atom.  You get a nice
>>non-collapsing ground state that occupies some space.  Add more
>>electrons and protons, resolve and lo, the occupied volume grows.
>>
>>Anyone cares to comment?
>
>Sure.  I agree 100%.  Even without the exclusion principle, EM repulsion
>would keep your chair leg from passing through the floor - but chemistry
>would be so different that trees would not likely exist from which to
>make the table.

     [deleted]

>-Scott
>--------------------

Consider a hydrogen molecule. The two electrons can be in a spin-antisymmetric,
space-symmetric or a spin-symmetric, space-anti-symmetric state (the exclusion
principle). Since spin interaction energies are very small, to a first approx-
imation computation of the ground state is a boson-vs.-fermion comparison.

It turns out that the space-symmetric state has lower energy. Even though the
electrons tend to occupy the same region of space, the positive energy of
repulsion between electrons and protons is overbalanced by the negative
energy of attraction of the protons towards the overlap region. In fact, for
a space- anti-symmetric wave function, the hydrogen atoms do not bond.

It is not at all clear to me that in a bosonic-electron system, the electrons
will not all occupy one state, not very much larger than a few atomic orbitals
in spatial extent, with the nuclei all very close to this very dense negatively
charged cloud. That is bosonic electrons would very effectively screen the
nuclear charge and this matter would be very much more dense than normal
matter. Nor is it obvious that the volume of matter will be prop-
oitional to the number of atoms.

Anyone to whom the answer is obvious, please explain.
thanks in advance.
-arun gupta
ag3L@andrew.cmu.edu
Newsgroups: sci.physics,sci.skeptic,alt.folklore.science
From: bhv@areaplg2.corp.mot.com (Bronis Vidugiris)
Subject: Re: The dangers in microwaved food...
Organization: Motorola, CCR&D, CORP, Schaumburg, IL
Date: Thu, 20 Aug 1992 16:33:00 GMT

In article <1992Aug20.015531.7842@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:
)there are serious health risks in eating.

There are very serious health risks in *not* eating.
From: sawyer@utahep.uta.edu (Lee Sawyer)
Newsgroups: sci.physics
Subject: Re: How to make big bucks using supersymmetry
Date: 21 Aug 92 00:40:00 GMT
Article-I.D.: utagraph.1992Aug20.233719.11390
    <1992Aug14.164822.10838@utagraph.uta.edu> 
    <MATT.92Aug19225852@physics16.berkeley.edu>
Distribution: na
Organization: University of Texas at Arlington High Energy Physics Group
NewsSoftware: VAX/VMS VNEWS 1.41
NntpPostingHost: utahep.uta.edu
MessageID: <20AUG199218401473@utahep.uta.edu>
X-Bytes: 1269

In article <MATT.92Aug19225852@physics16.berkeley.edu>, matt@physics.berkeley.edu writes...
>In article <1992Aug20.030038.22420@utagraph.uta.edu> sawyer@utahep.uta.edu (Lee Sawyer) writes:
> 
>>     This is what I eleuded to by mentioning missing tranverse energy
>> events. Typically SUSY searches have centered on gluino > quark
>> antiquark LSP, where LSP = the Lightest Supersymmetric Particle
>> and is usually assumed to be the photino. 
> 
>A little more precisely, the photino, the zino, and the two neutral
>higgsinos are, in general, not mass eigenstates.  The four neutralinos
>are what you get when you diagonalize the mass matrix for these four
>particles.  And, indeed, it is usually assumed that the lightest
>supersymmetric particle is one of these four neutralinos.
>
>Matthew Austern   

 Yeah, Matt, technically I should have said Chi_0 (or is it Z_1 ? Do 
you follow the East Coast or West Coast notation ?) But yes, the
lightest neutralino. By the way, Xerxes Tata  U of Hawaii at Manoa 
has a very nice concise review of SUSY out, in the form of a lecture 
presented at the Mt Sorak Symposium on "Beyond the Standard Model"

       ================
         Lee Sawyer

         Dept of Physics
         Univ. of Texas
               at Arlington
Newsgroups: sci.physics
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Subject: Re: Length scales in physics 4 - the Planck length
Organization: National University of Singapore
Date: Wed, 19 Aug 1992 02:48:24 GMT

I honestly don't see the point of this kind of thing. All it does is to
make people think that they understand things, when in fact they don't.
I have nothing against sloppiness per se, but to discuss black holes in
terms of escape velocities is just completely misleading and serves no
purpose that I can see. I would really like to understand why physicists
enjoy this kind of thing.
By the way, JB: you say that Ashtekar et al suggest that spacetime
becomes a weave of knots etc etc: in what space?
From: matt@physics16.berkeley.edu (Matt Austern)
Newsgroups: sci.physics
Subject: Re: Length scales in physics
Date: 22 Aug 92 22:06:02
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
	<1992Aug23.014932.15108@Princeton.EDU>
Reply-To: matt@physics.berkeley.edu
NNTP-Posting-Host: physics16.berkeley.edu
In-reply-to: nextc.Princeton.EDU!mdd's message of Sun, 23 Aug 1992 01:49:32 GMT

In article <1992Aug23.014932.15108@Princeton.EDU> nextc.Princeton.EDU!mdd (Mark D. Doyle) writes:

> Of course, there is always the constant 192 (pi)^3 that appears when you  
> calculate the width of the muon. Dimensional analysis misses by 3 orders  
> of magnitude. Useful to remember for qualifying exams. 

Well, sort of...  On the other hand, you can get the width of the muon
by an argument that's very similar in spirit to dimensional analysis,
if you remember the appropriate factors of 4 pi for phase space.  I
suppose it just means that "dimensional analysis" means more than
getting the units right; it means understanding the physical reasons
why the units have to work out the way they do.  (Similarly: you know
that the Bohr radius has to be proportional to the inverse of the mass
of the electron, but is it 1/m_e, or alpha/m_e, or alpha^2/m_e,...)

I'm reminded of a problem on the final exam for my first particle
physics course; we were supposed to estimate some decay rates, and
were explicitly told that what was wanted was an estimate, not an
exact calculation.  One of those decay rates was zero at tree level,
and proceeded only through a loop diagram; the professor took off
points for everyone who forgot to include the factor 1/(16 pi^2) for
the loop.  I was one of the people who forgot, and I was annoyed at
the professor at the time; in retrospect, though, it's clear that she
was right.  This is the sort of intuition that is necessary if you
really want to play the order-of-magnitude game well.
Newsgroups: sci.physics
From: nat@netcom.com (Nathaniel Stitt)
Subject: weak force
Date: Sun, 23 Aug 92 11:38:42 GMT
Organization: Netcom - Online Communication Services (408 241-9760 guest)


The articles I just read about the strong force are excellent!  This is
the kind of stuff that makes me glad I have not given up reading news
entirely.

Ok, same question about the weak force: Is there a formula that describes
the action of the weak force?

Thanks!
nat
Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: An easy problem in general relativity
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Thu, 13 Aug 1992 01:32:00 GMT

jbaez@nevanlinna.mit.edu (John C. Baez) writes...
>Don't worry, I wasn't planning on making bets on that.  I still wish I
>could place some bets for more that 1 cent on supersymmetry though --
>anyone around REALLY believe there's a >50% chance of it being confirmed
>within our lifetimes?

You are a wimp. :-) I would be happy to make your side of the bet 'worthwile'
to you, but I was hoping we could be a little classier than sending money!
You can choose your own reward, so long as it is within a grad student's
budget. If I remember correctly, Hawking and Thorne wagered a subscription
to Playboy, over the possible discovery of a black hole (can anybody verify
this?) If you insist on real money, then I want the deadline pushed to 2010
as Scott suggests. In any case, I want a check for 1 US cent, with the memo:
'Strong evidence for SUSY.' I hope that won't be TOO much of a burden, I know
how damaging such things can be to the reputation of a future big shot! :-)

Dave Ring
dwr2560@zeus.tamu.edu
Newsgroups: sci.physics,sci.astro
From: bedding@physics.su.OZ.AU (Tim Bedding)
Subject: Re: Fossil Paradox (was: Structure of Time)
Organization: School of Physics, University of Sydney, Australia
Date: Mon, 17 Aug 1992 09:56:11 GMT

In article <1992Aug17.105608.421@ecc.tased.edu.au> ecc_jim@ecc.tased.edu.au writes:
>
>There was a short story like this where a guy trod on a butterfly and totally
>changed everything. What was it called?
>
"The Sound of Thunder", as I recall.  Which was what he heard when he got
back to the present to find it changed: his travelling partner blew him
away with a shotgun for being a jerk.  :-)
--
+--------------------------------+-------------------------------------------+
|  Tim Bedding                   |   Email: bedding@astrop.physics.su.OZ.AU  |
|  School of Physics,            |   Phone: +61 2 692 (2727|2884)            |
|  University of Sydney,         |   Fax  : +61 2 660 2903                   |
|  Sydney, NSW, 2006, Australia  |      A little pain never hurt anyone.     |
+--------------------------------+-------------------------------------------+
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Origin of universe as quantum fluctuation?
Date: 16 Aug 92 19:47:19 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 <1992Aug14.024055.21470@nuscc.nus.sg>, matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes...
>Scott: Physics would be impossible if we keep worrying about new physics
>around the corner for which there is no evidence. I think we can say the
>following.

I look at it another way.  It is shortsighted to expect that our current 
models of physics are applicable in domains where experiments have not been
done.  In fact, particle physics has cutoff energies built right into the
theory which are interpreted as indicating the scale at which new physics 
must come into play to save us from wierdities.  The classic example is
the ultraviolet divergence of QED integrals.  You put in a cutoff mass
at which you stop bother integrating the contributions of more and more
energetic photons.  How do you justify this?  You say that we expect that
new physics will arise to modify the photon propagator at sufficiently 
high energy.  The wonderful thing about QED is that the results you get 
don't end up depending on the cutoff frequency you choose. But the fact
remains that the theory is built upon the assumption that there exists a 
cutoff - photons at high energy don't propagate like photons at low energy,
and we don't know enough to write the correct propagator - we just
introduce a cutoff and move on.

-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@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Property of waves
Date: 17 Aug 92 20:54:53 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 <1992Aug17.105438.13053@organpipe.uug.arizona.edu>, kam@soliton.physics.arizona.edu (Kam-Yuen Kwong) writes...
>  Probably somebody would like to enlighten me about this: 'Does
>the character, "longitudinal" or "transversal", of a wave come
>from empirical observations or the analytical property of the wave
>equation and its constraints'? In other words, can we tell a wave
>longitudinal or transversal by just looking  into its wave
>equation? At least, in the EM wave, analytically, we know the
>vector of  E and B is transversal to the Poynting (energy flow)
>vector. How about others like string wave, water wave, acoustic
>wave etc.?

There are two issues here. 

(1) Can a given system support transverse and longitudinal vibrations?
That depends on the wave equation.  As you pointed out, EM waves do not
have longitudinal polarizations.  That's built right into the equations.
Other fields, such as vibrations of a rigid rod, can have either transverse
or longitudal modes.  

(2) Is a given vibration (in a system which allows both,) transverse or 
longitudinal?  That depends on the boundary conditions, and nothing in the
wave equation can tell you.

For example, whether a given vibration of a rigid rod is transverse or
compressional (longitudinal) depends entirely on how you strike it.

-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
From: hporopudas@tnclus.tele.nokia.fi
Subject: FAULT  (Survey,Subject?)
Organization: Nokia Telecommunications.
Date: Fri, 21 Aug 1992 10:28:17 GMT



 What are these postings "Survey", "Subject?". ??

 These postigs seems to come from unknown sources from other newsgroups
 directly here.

 Is there somewhere fault in this network. ?
                    -----

          Hannu.

Newsgroups: sci.physics
From: barry@arnold.math.ucla.edu (Barry Merriman)
Subject: Re: the nature of exclusion
Organization: UCLA, Mathematics Department
Date: Thu, 20 Aug 92 02:11:52 GMT

In article <1992Aug19.130152.15632@newstand.syr.edu> middle@npac.syr.edu (A.  
Middleton) writes:
> In article <1992Aug18.214628.9544@math.ucla.edu>, barry@arnold.math.ucla.edu  
(Barry Merriman) writes:
> >but then that implies as I compress in space I expand in
> >momentum, which would seem to imply ther temperature goes up.
> > ...
> 
> More momentum does not necessarily mean higher temperature. Zero
> temperature means putting the fermions in the lowest energy state
> POSSIBLE. Since the lowest energy state is one electron of each
> spin in each momentum state, the ground state has kinetic energy.
> This kinetic energy will grow as the box shrinks.

Ok, but one would like to understand this in physical, causal 
terms if possible. I mean, yes there is that _relation_, but can
we go one step further and develop a casual chain of the form

exclusion principle -> "statistical repulsion" -> more energy in ground
state as it is spatially compressed.

and actually understand the physical mechanism of the stat repulsion?
Maybe not, but it would sure be nice if one could have an intuition
about it, rather than just accepting it.




--
Barry Merriman
UCLA Dept. of Math
UCLA Inst. for Fusion and Plasma Research
barry@math.ucla.edu (Internet; NeXTMail is welcome)
From: gilligan@bldrdoc.gov (Jonathan Gilligan 303-497-3861)
Newsgroups: sci.physics
Subject: Re: Weak interactions, biology and the SSC
Date: 14 Aug 92 20:10:46 GMT
Organization: National Institute of Standards and Technology

I have trouble with the idea that the weak force would have anything
to do with biological chiral asymmetry because the coupling of the
weak force to molecules is so much less than the thermal noise. Thus,
the molecules are continually kicked out of whatever tiny well the
weak force makes for them. Consider that to about 2 micro-eV, the
binding energies of small molecules can be accounted for by the
electromagnetic force alone (the energy scale is set by the
Hartree---27.2 eV).  Rotational and vibrational intervals are known to
even greater accuracy, again without needing to invoke the weak force.
The thermal energy at 295 K is about 25 milli-eV: more than four
orders of magnitude greater than the maximum coupling of the weak
force.

I have a hard time believing that biological chirality developed due
to a part-in-10^7 or smaller effect that's more than four orders of
magnitude below the thermal noise.

However, even if it were the case that the weak force were
biologically significant, I think that results relevant to biology
would be more likely to come from work like Carl Wieman's. Wieman has
measured the the weak mixing angle by measuring parity violating
electronic transitions in atomic cesium.  His work is competitive with
many high-energy experiments (See Review of Particle Properties (Phys.
Rev. D 45 (11) Part II (June 1992), p. III.63, Table 3) and requires
equipment on the scale of a million dollars total.  Recent
developments in diode laser technology may push the capital costs of
future experiments down significantly.

---Jon

-- 

Disclaimer --- The government probably disagrees with my opinions.
Newsgroups: sci.physics
Subject: Re: Symmetries, groups, and categories
From: mcirvin@husc8.harvard.edu (Mcirvin)
Date: 15 Aug 92 00:17:56 GMT
 <4537@news.duke.edu> <1992Aug14.195651.22652@galois.mit.edu>

jbaez@zermelo.mit.edu (John C. Baez) writes:

>Also, at very high relative momenta,
>i.e. at very short distance scales, quarks and gluons ARE approximated
>well by free particles.  This is so-called "asymptotic freedom" - the
>opposite of "infrared slavery".  Some experimentalist can remind us when
>they first found evidence for this, which was a big boost for Feynman's
>"parton" model.

And, by the way, it is not hard to actually derive ultraviolet freedom
from QCD, as opposed to infrared slavery.  Asymptotic freedom is
better-understood because, by definition, the coupling constant is weak
at those scales, so it's possible to get results out of perturbation
theory.  Under some (probably weak) definition of the word "proof,"
asymptotic freedom in the theory has been proven.  As momentum transfer
gets large, the coupling constant becomes smaller than ~1 (so
perturbation theory begins to apply) and eventually approaches zero. 

One application of it is in what I'm studying now, which is the 
simplification that occurs when some of the quarks under consideration
are very massive.  The momentum transfer necessary to give the heavy
quark a significant shove is large enough that the strong force becomes
very weak, so QCD is effectively put out of the business of changing
the heavy quark's velocity-- this is Georgi's "velocity superselection
rule."  It becomes possible to write down a low-energy effective
theory in which heavy quarks moving at different velocities are
described by independent fields, which can interact only through
electromagnetic or weak couplings.  The velocity of the field
in question ends up in the heavy quark propagator.  This kind of
reasoning becomes important when studying things like B meson
decays.  

-- 
Matt McIrvin, professional gradgrind, amateur Usenet drifter 
Newsgroups: sci.physics
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: Hubble constant?
Organization: University of Virginia
Date: Wed, 19 Aug 1992 02:37:35 GMT

In article <Aug.18.21.15.05.1992.16614@ruhets.rutgers.edu> bweiner@ruhets.rutgers.edu (Benjamin Weiner) writes:

>>I have a theory that everyone here on usenet has a superpartner: an evil
>>twin that looks just like them but is 1000 times heavier.  The reason
>>why nobody has ever seen one of these superpartners is that they never
>>make their appointments.  :-)
>
>I'm Dale Bass's evil twin.  Or maybe I'm Dale Bass.  Have you ever
>seen me and Dale in the same room at the same time?

     I'm about 6'1'', 200 lb.  So, I'd hate to meet *you* in a dark alley.

     Where do you buy your suits?

                                   dale bass

-- 
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926