HDTenEightyP/NetNews huggingface dataset:
From: ag3l+@andrew.cmu.edu (Arun K. Gupta)
Newsgroups: sci.physics
Subject: Re: Volume Occupation
Date: 18 Aug 92 21:58:19 GMT
Organization: Physics, Carnegie Mellon, Pittsburgh, PA




If N is the number of atoms, then the binding energy
of an aggregate of N atoms E(N) should be proportional to N,
for large N.
(If E[N] ~ N^a, then putting together two chunks of matter
would release energy E(2 N) - E(N) ~ (2^a -1) N, and if
a is greater than 1 , then even combining small chunks of
matter would release tremendous amounts of energy.)

The proofs of stability of matter come from estimating upper
and lower bounds on E(N). (Clever tricks which I don't know are used.)

For matter with bosonic electrons, a = 5/3. A volume estimate also
pops out of the analysis, the volume ~ 1/N.

If the nuclei were fermionic, eventually when they become close enough
for their wavefunctions to overlap significantly, they would stabilize
matter (matter would be very dense), and thus the most unstable matter
is bosonic nuclei with bosonic electrons. For this matter a = 7/3
(am quoting from memory, might be wrong. Nor do I remember how the
volume scales with N.)

My intuitive guess of what goes on is as follows:

the Hamiltonian includes a sum over the potential energy of
interaction of every pair of particles. Thus, one might expect
the ground state energy to go as the number of pairs ~ N^2.

This won't happen if the significant terms in the energy sum
come from nearby neighbours only. The exclusion principle
guarantees that the number of neighbours remains a small number
rather than growing with N. Electrostatic repulsion is not
strong enough to do this.

-arun gupta
ag3L@andrew.cmu.edu
From: mikey@ontek.com (euphausia superba)
Newsgroups: sci.physics
Subject: Re: Snarfy's Equation
Date: 20 Aug 92 18:05:06 GMT
Followup-To: junk
Organization: Ontek Corporation -- Laguna Hills, California

In sci.physics, snarfy@cruzio.santa-cruz.ca.us writes:
| 
|                      R=6.826*(D^-2)
| 
|                  Where R = Ohms per 1000ft
|                  and   D = Diameter of round copper conductor in mm.

R is nice, but at high frequencies impedance will come
in to play and the formula will not be accurate.   At 
even higher frequencies, the wire will lose electromagnetic 
energy, which will be radiated off into space at the speed 
of light.

Or is Snarfy's Equation to be taken as literally as
Ohm's and Kirchoff's Laws?

       the krill

Xref: sparky sci.physics:13231 alt.folklore.urban:21867 sci.electronics:14694
From: klg@panda.mc.duke.edu (Kim Greer -- rjj)
Newsgroups: sci.physics,alt.folklore.urban,sci.electronics
Subject: Re: Fun with droplets
Date: 21 Aug 92 14:59:18 GMT
Followup-To: sci.physics
Distribution: usa
Organization: Duke University, Nuclear Medicine

In article <1992Aug20.224428.25520@sj.nec.com> bigdave@texas.tdd.sj.nec.com (David Sweeney  x2987) writes:
+acase@reed.edu (Andrew Case) writes:
++
++      Oh Boy! You have wandered into my turf. I just spent nine months
++studying exactly this phenomenon (isn't physics great?). The coffee
++droplets are prevented from coalescing by a thin (~1000 Angstrom) 
++film of air trapped between the droplet and the surface of the
++coffee.      [stuff deleted]
++in just about any liquid. I have gotten droplets to last for up
++to eight minutes under controlled conditions.
+
+You study this at a university?  Damn!  I study my coffee here at work in 
+great detail on a regular basis.  I didn't know I could get college credit 
+for it!

  College Credit!?  Heck, you can get money from the guvmint to study this
stuff.  Or, maybe even get even more money _not_ to study it, in the same
way farmers allegedly get paid not to plant crops.

+Dave Sweeney     bigdave@tdd.sj.nec.com
+I watch the water cooler pretty closely, too
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     .... and especially during sweeps week!

K "does that have anything to do with why color radio failed?" G
-- 
Kim L. Greer                       
Duke University Medical Center		 klg@orion.mc.duke.edu
Div. Nuclear Medicine  POB 3949		 voice: 919-681-5894
Durham, NC 27710  		         fax: 919-681-5636
From: whit@milton.u.washington.edu (John Whitmore)
Newsgroups: sci.physics
Subject: Re: sea waves
Keywords: waves
Date: 19 Aug 92 03:33:51 GMT
Organization: University of Washington, Seattle

In article <boudouvi.714144870@theseas> boudouvi@ntua.gr (Andreas Boudouvis) writes:

>Why the crests of sea waves are white (esop. when the waves 
>break at the seashore?)

	Waves in shallow water are dispersive (also wind-driven waves),
in the sense that the crest of the wave travels faster than the base
of the wave.  The crest then travels out from over its support,
and falls-down-goes-boom.  This is the reason for whitecaps that
I've always been told; it is consistent with the shallow-water wave
equation (but I haven't run the exact numbers).

	John Whitmore
Newsgroups: sci.physics
From: carl@aoa.aoa.utc.com (Carl Witthoft)
Subject: Re: the nature of exclusion
Organization: Adaptive Optics Associates
Date: Tue, 18 Aug 1992 11:54:32 GMT

In article <1992Aug14.210429.23650@galois.mit.edu> jbaez@zermelo.mit.edu (John C. Baez) writes:
[original question "why can't I force 2 fermions into one state?]
>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 -- they will just get squished
>over to regions of high momentum hence high energy -- so it takes a lot
>of energy to squish down a fermionic gas.
x
An interesting continuation of this: if you pull enough energy
out of the right fermionic system and squish it enough, fermions
occasionally pair off to form boson-like units.  These units then
drop into a common energy state.  Cold He3 is one example, if I
remember correctly :=).
x
x
x
x


-- 
Bobby Newmark, aka  Carl Witthoft @ Adaptive Optics Associates
aoa!carl@bbn.com  carl@aoa.utc.com
54 CambridgePark Drive, Cambridge,MA 02140 617-864-0201
**Just say NO to HMOs**
From: matt@physics16.berkeley.edu (Matt Austern)
Newsgroups: sci.physics
Subject: Re: How to make big bucks using supersymmetry
Date: 19 Aug 92 22:58:52
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
Distribution: na
	<25611@dog.ee.lbl.gov> <1992Aug20.030038.22420@utagraph.uta.edu>
Reply-To: matt@physics.berkeley.edu
NNTP-Posting-Host: physics16.berkeley.edu
In-reply-to: sawyer@utahep.uta.edu's message of 20 Aug 92 04:03:00 GMT

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.

The problem with the minimal supersymmetric standard model (MSSM) is
that there are a whole lot of unknown parameters---masses of the
superpartners, mixing angles, and so on.  The phenomenology of the
MSSM is very different for different values of those parameters, so it
isn't easy to make any definite predictions.

It also isn't at all easy to drive a stake through the heart of the
MSSM; all any experiment can do is to exclude some region in this
multi-dimensional parameter space, and there will always be some
allowed region left.

Haber and Kane wrote a review article (Phys. Rept. 117, 75 (1985))
which discusses some MSSM phenomenology.  And, of course, there's
always EHLQ.

--
Matthew Austern              I dreamt I was being followed by a roving band 
(510) 644-2618               of young Republicans, all wearing the same suit,
matt@physics.berkeley.edu    taunting me and shouting, "Politically correct
austern@theorm.lbl.gov       multiculturist scum!"... They were going to make
austern@lbl.bitnet	     me kiss Jesse Helms's picture when I woke up.
Newsgroups: sci.physics
Subject: Re: math for physics
From: harper@kauri.vuw.ac.nz (John Harper)
Date: Mon, 17 Aug 1992 08:44:42 GMT
Organization: Victoria University of Wellington

My 2c worth:
Abramowitz & Stegun for properties of functions and numerical tables
Jahnke & Emde (Dover Books) for pictures of how functions behave in the
  complex plane (this is the one area where A&S did not supersede J&E)
BUT neither of the above gives proofs. You may need these (e.g. if suspecting
a typo in some book); if so:
Whittaker & Watson 
FWJ Olver "Intro. To Asymptotics and Special Functions" (Academic Press 1974)
YL Luke "The special functions and their approximations"(Academic Press 1969)
If you want a property of functions that's not in the above the refs in A&S
for particular functions are good. 
John Harper Mathematics Dept. Victoria University Wellington New Zealand
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: Hubble constant?
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Thu, 13 Aug 1992 22:59:00 GMT

scip1061@nuscc.nus.sg (Marc Paul Jozef) writes...
>A more realistic solution h of Einstein's G(g) = d
>for a grid would be some perturbation of g which has
>Schwarzschild-bumps around the grid-points. But 
>these bumps do not interest me; I want to know
>about the mutual behaviour of the grid-points. And
>this behaviour is described by g. (which satisfies G(g) = 0).

the perturbation is not small. In fact it completely changes the large
scale geometry.

Let me present a toy model. One space dimension, one time dimension. The
space dimension will be a circle, and there will be 10 equally spaced
point masses. The resulting spacetime will look sort of like a pumpkin.
Except within each 'segment' the spacetime will be intrinsically flat.
In other words you could create a model of this spacetime by pasting
together 10 lens shaped pieces of paper. One might unpaste them, and
touch them together at the point T=0 so that they fan out in a 'flower'
configuration. Then, since the whole plane would be an empty universe,
each segment looks like _part_ of an empty universe. And since each segment
is empty, G(g) = 0. Yet the global behavior (the pumpkin shape) is very
close to the spacetime which would result from a homogeneous distribution.

Dave Ring
dwr2560@zeus.tamu.edu
Newsgroups: sci.physics
From: huberman@Xerox.com (Bernardo Huberman)
Subject: New Book on the Physics of Computation
Reply-To: huberman@Xerox.com (Bernardo Huberman)
Organization: Xerox PARC
Date: Tue, 18 Aug 1992 18:03:50 GMT




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


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edited by B A Huberman  (Xerox Palo Alto Research Center)


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Physical  Entropy,  Measurements,  and  the  Second  Law  (W   Zurek); 
Cooperative  Problem  Solving  (S   H  Clearwater,  T  Hogg  &   B   A 
Huberman);  Directed-Graph Epidemiological Models of Computer  Viruses 
(J O  Kephart & S R White); The Use of Physics Concepts in Computation 
(G Fox).

READERSHIP :   Computer scientists and physicists.
 
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Newsgroups: sci.physics
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Subject: Re: How to make big bucks using supersymmetry
Organization: National University of Singapore
Date: Sat, 15 Aug 1992 01:38:09 GMT

There is one item that you gentlemen have forgotten. Do you really think
that american pennies will still be legal tender in 2010? By then, the
smallest coin will be small disc of brass with $1000 inscribed on one
side, and a portrait of R Reagan on the other.
Newsgroups: sci.physics,sci.astro,sci.philosophy.tech,talk.religion.misc
From: sasghm@theseus.unx.sas.com (Gary Merrill)
Subject: Re: Fossil Paradox (was: Structure of Time)
Originator: sasghm@theseus.unx.sas.com
Date: Wed, 12 Aug 1992 18:41:21 GMT
Distribution: sci,talk
Organization: SAS Institute Inc.


A number of years ago David Lewis was writing some papers on the logic
of time travel.  I seem to recall that this was when he was visiting
at some university in Australia.  I did not manage to read any of
these, but I have a vague recollection of seeing at least one
published version.  It may have been in _Nous_ or the _Australasian_
Journal_of_Philosophy_.  Anyone familiar with this?  (Or with any
unpublished stuff he might have done?)
-- 
Gary H. Merrill  [Principal Systems Developer, C Compiler Development]
SAS Institute Inc. / SAS Campus Dr. / Cary, NC  27513 / (919) 677-8000
sasghm@theseus.unx.sas.com ... !mcnc!sas!sasghm
Newsgroups: sci.physics
From: minsky@media.mit.edu (Marvin Minsky)
Subject: Re: marbles in a container
Organization: MIT Media Laboratory
Date: Fri, 14 Aug 1992 03:03:26 GMT

In article <1992Aug13.201500.22023@cs.sandia.gov> sjplimp@cs.sandia.gov (Steve Plimpton) writes:
>korfhage@weston.poly.edu (Willard Korfhage) writes:
> 
>> A question came up recently about marbles in a container: If I dump a
>> bunch of marbles in a container (randomly positioned, rather than
>> carefully placed), what are the statistics concerning how many points
>> of contact each marble has with other marbles?
> 
>>   Willard Korfhage
>>   korfhage@weston.poly.edu
>
>This is a problem related to grain boundary structure in solids.  I
>have a Xeroxed pg. 304 which I wrote on the top:
>
[stuff deleted]

>J. D. Bernal  ....   quotes the Reverend Stephen Hales in
>his 1727 book "Vegetable Staticks" (no joke)
>
>'I compressed several fresh parcels of Pease in the same Pot with a
>force equal to 1600, 800, and 400 pounds; in which Experiments, tho'
>the Pease dilated, yet they did not raise the lever, because what they
>increased in bulk was, by the great incumbent weight, pressed into the
>interstices of the Pease, which they adequately filled up, being
>therby formed into pretty Dodecahedrons.'

But I remember reports of more recent experiments in which the number
From: kruppd@sun.pcl.ac.uk (Declan Kruppa)
Newsgroups: sci.physics
Subject: fluid dynamics
Date: 19 Aug 92 12:42:13 GMT
Organization: Polytechnic of Central London

Is there a newsgroup for users of 
computational fluid dynamic calculations. ?
Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: SU(5) GUT (was Re: Superbashing ...)
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Sat, 15 Aug 1992 05:39:00 GMT

phfrom@nyx.uni-konstanz.de (Hartmut Frommert) writes...
>2. Though I'm not so familar with the currently best data situation, I'm
>   aware that every SU(5) model has difficulties with 2 features:
>   a. The SU(5) theories predict a constant (d-)quark : lepton mass 
>      relation which is only poorly fulfilled

From Collins,Martin,Squires "Particle Physics and Cosmology": "Fortunately,
the successful prediction for m(bottom)/m(tau) is hardly changed [when
SUSY is introduced]". It is actually made slightly worse. But this is
hardly a decisive test of the models. The other generations are normally
not even considered, because the RGE's are not reliable at such low scales.

>   b. The negetive result of proton decay experiments imply now a
>      $\tau_p > 10^{32} years$ (correct me if that's out of date) 
>      which shifts the GUT gauge boson mass up, and gives reason to doubt if 
>      SU(5) GUT is realized in nature.
>Question: Is this situation improved anyhow by SUSY SU(5) ?

Non-SUSY SU(5) predicts 10^30 years.

SUSY SU(5) predicts the same process to take 10^34 years. But there are
other decay modes which bring tau_p down to around 10^32. Also I think
the 10^32 experimental limit is mode dependent. I know that extra higgses
or generations ruin the proton lifetime, so it must be getting close.

Dave Ring
dwr2560@zeus.tamu.edu
Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: SU(5) GUT (was Re: Superbashing ...)
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Tue, 18 Aug 1992 05:47:00 GMT

phfrom@nyx.uni-konstanz.de (Hartmut Frommert) writes...
>>Non-SUSY SU(5) predicts 10^30 years.
> 
>>SUSY SU(5) predicts the same process to take 10^34 years. But there are
>>other decay modes which bring tau_p down to around 10^32. Also I think
>>the 10^32 experimental limit is mode dependent. I know that extra higgses
>>or generations ruin the proton lifetime, so it must be getting close.
> 
>So we are in the situation that there's no experimental preference of
>SUSY or non-SUSY SU(5).

Non-SUSY SU(5) is ruled out by the experimental limit.

>                         In addition, we canNOT say at the present stage if a 
>supergroup of SU(5) should be employed (SUSY or not), or if a unification is 
>present at all -- SU(3) x SU(2) x U(1) as is may well be the starting point.

Then sin^2(theta) is a completely free parameter. Which SUSY GUT predicts
to 3 significant figures!

SUSY may be only 60-40 but GUT, or something like it, is at least 90-10. :-)

Dave Ring
dwr2560@zeus.tamu.edu
From: ted@physics2 (Emory F. Bunn)
Newsgroups: sci.physics
Subject: Re: Hubble constant?
Date: 14 Aug 1992 18:50:40 GMT
Organization: /etc/organization
NNTP-Posting-Host: physics2.berkeley.edu

In article <Aug.13.16.31.25.1992.25521@ruhets.rutgers.edu> bweiner@ruhets.rutgers.edu (Benjamin Weiner) writes:
>willner@cfa.harvard.edu (Steve Willner) writes:
>>If you are willing to accept a non-zero cosmological
>>constant, though, you can have a flat universe with \Omega =
>>\Omega_baryon = 0.2 and old enough to solve the horizon problem, the
>>structure problem, and the "oldest stars" problem.
>
>Is this what the "isocurvature baryon" universe is?  

I think (although I could be wrong) that the "isocurvature baryon"
model refers to a universe in which there are only baryons (enough
to make Omega =0.2 or so) and no cosmological constant.  So it's not
flat.  When cosmologists talk about models with a nonzero
cosmological constant, they usually refer to them as "cosmological
constant models" or "Lambda models" (Lambda being the conventional
symbol for the cosmological constant.)

I'll let somebody else explain what "isocurvature" means in this
context, because I always get it wrong.

-Ted



Newsgroups: sci.physics,sci.astro,sci.philosophy.tech,talk.religion.misc
From: peters@physics.ubc.ca (Dan Peters)
Subject: Re: Fossil Paradox (was: Structure of Time)
Organization: University of British Columbia, Vancouver, B.C., Canada
Date: Thu, 13 Aug 1992 20:07:15 GMT

Ari.Huttunen@hut.fi (Ari Juhani Huttunen) writes:

>The answer to that problem is simple. A basic law that has not yet been
>stated is the law of _causality_. You could travel backwards in time but
>you would end up so far away from 'here' that when you traveled back
>with the speed of light, it would at best be the present time.

Not good enough. All you're saying is that you cannot jump to a point in
your past light-cone, while you may be able to jump to a point which is
"elsewhere" (i.e. spacelike separated from your starting point). But suppose
you make such a jump *twice*? You start from point A, jump to point B
(spacelike separated from A), then jump to point C (spacelike separated from
B) - what's to stop you from landing in the past light-cone of A? Perhaps you
can get around it by saying your time machine has to "remember" somehow
where/when you started from, and dictate a bunch of arbitrary-sounding rules,
but this gets really fishy, fast.

Drin

Newsgroups: sci.physics,sci.chem,news.groups
From: phillies@wpi.WPI.EDU (George D. Phillies)
Subject: Preprint servers
Organization: Worcester Polytechnic Institute
Date: Wed, 12 Aug 1992 15:46:49 GMT

In <1992Aug12.074607.10886@midway.uchicago.edu>
trivedi@curie.uchicago.edu (Anil Trivedi) notes

>keith@msmri.med.ubc.ca writes:
> > I think the automated preprint servers which are popping up at various
> > sites are a wonderful idea but how does one find out about new
> > servers and what topics the current servers cover?

and lists 9 physics preprints servers.  This was a valuable public service, 
which should usefully be covered in a general way to include all fields of
science and engineering.  Either a new newsgroup, e.g. news.servers, or
a FAQ list on servers, distributed to sci.*, might work.

George Phillies
Professor of Physics
phillies.wpi.wpi.edu


Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: How to make big bucks using supersymmetry
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Thu, 13 Aug 1992 23:32:00 GMT

jbaez@riesz.mit.edu (John C. Baez) writes...
>Are you planning on being in grad school until the year 2010?  In any
>event, to make it mildly exciting, I would propose to give you $40 if
>strong evidence for SUSY is obtained by 2010, if you give me $60 if it's
>not.  This would count as proof that you believe your original statement
>that SUSY has a 60% chance of being true.
> 
>>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! :-)
> 
>If this 1-cent bet is all you're up for, how much money would you be
>willing to give me if they DON'T find strong evidence?  I'm sorry if I
>seem so crass, but frankly a subscription to Playboy is not my idea of
>"classy".  :-)  Feel free to propose anything.

I agree to your $60. But to me $40 is an empty victory. I want the penny.

>Then we will have to get some idea of what counts as 'strong evidence
>for SUSY'.  Convergence of coupling constants alone does not cut it in
>my opinion.  

I trust you.

Well... to be perfectly honest, I would _most_ enjoy needling you publicly
if you refuse to pay! :)

See you in 2010 (or preferably before!)

Dave Ring
dwr2560@zeus.tamu.edu