HDTenEightyP/NetNews huggingface dataset:
From: johno@sdd.hp.com (John Ongtooguk)
Subject: Re: Time
Reply-To: johno@sdd.hp.com (John Ongtooguk)
Organization: Hewlett-Packard, San Diego Division
Date: Thu, 9 Apr 1992 04:42:42 GMT

In article <1992Apr8.071015.17512@ifi.uio.no>, jarlo@ifi.uio.no (Jarl Magne Michael stensen) writes:
|> 
|> I would want to ask all of you this wery simple (?) question: what is time?
|>
   And here is a simple answer. If you take the twins paradox to it's
   extreme and allow one of the twins to move around like a photon he
   is normal to the time axis; he is everywhere he going to ever be and
   everywhere he has ever been at any point in time. This is the result
   of rearranging e=mc^2 to c=sqrt(e/m); the photon is massless so it is
   not bound by the speed of light, which by the way explains Bell's
   inequality. The vacuum energy forces the above to be very asymptotic.
   The presence of mass results in the speed of light, which also explains
   the second law of thermodynamics, as the lack of mass would allow
   one to be normal to the time axis and not subject to it's harsh 
   judgement. So time is mass. [ Lots of B=) :=) %=) |=) 8=) ]

   John Ongtooguk (johno@sdd.hp.com)
From: hall@vice.ICO.TEK.COM (Hal Lillywhite)
Newsgroups: sci.physics
Subject: Re: People against Supercollider???
Date: 6 Apr 92 21:33:05 GMT
Distribution: na
Organization: Tektronix Inc., Beaverton, Or.

In article <22528@dog.ee.lbl.gov> sichase@csa1.lbl.gov writes:
 
>The reason that we don't [delay SSC to wait for improved
technology] is that the particle physicists are in a race against
>time.  You don't do good physics by verifying someone elses result.  This
>competative incentive to move fast is a strong driving force in the advancement
>of science.  For the most part it is a very good thing.  However, in this case
>I wonder if we are leaping just a little to soon, without looking quite enough.

Exactly the sort of thing which makes me doubt the wisdom of
building SSC now.  While the competitive nature of science has
driven many new discoveries I find it hard to justify spending $10G
of taxpayers money so one researcher can reach the goal ahead of
another.  I think we need to remember that this money comes from the
guy trying to put his kids through college, the single mother trying
to keep up with her job and family, and others with equally pressing
needs.  These people have little choice whether they are going to
subsidize our toys, the government takes their money anyway.

So what if somebody in Germany or Japan discovers the Higgs first, 
what is damaged other than our pride?  It is highly unlikely that 
such a discovery would allow any country to either dominate the
semiconductor market or gain any military advantage.  

Maybe we should back off in this particular rat race.
Newsgroups: sci.physics
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: MD visualizations
Date: 13 Apr 92 20:38:40 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Organization: SCRI, Florida State University

In article <1992Apr13.183243.24900@cs.wayne.edu> kil@pandora.cs.wayne.edu (Joseph I. Landman) writes:
>Hello fellow netters!
>
>I am in need of information regarding visualization of molecular
>dynamics data.  I have triples denoting atomic positions in a lattice,
>and all I want to see are spheres wher each atom type is.  I have
>typically 64 or 65 atoms, of 2 different species.  I would like to 
>display all the atoms on the screen with a color assigned to each atom
>type.  I would like to specify the plane (or normal vector) from which I
>view the crystal.  I would like to navigate through the crystal to look
>at defects as they form. 

What you want is something like SciAn, developed by some folks here at 
SCRI.  It will do all these things and more.  It is even free, having 
been developed by people on gov't contract, and is now in beta release.
Its best feature is that is works on 3-D fields of many kinds and allows 
you to manipulate the display with tools that are quite natural to use. 
Unfortunately ...

>                          Best of all, I would like to do all of this on
>my PC without great expense.  I would be happy with some X widget, but
>the PC is the preferential platform for this (why? because that is the
>sort of computer that currently exists within our group... ;->)

... it runs on graphics workstations.  It is best on a Silicon Graphics 4D, 
where the flyby control is smoothest, but is also supported on IBM RS/6000 
platforms that have graphics library (GL) support.  Anything less and the 
rendering and lighting is hopeless, they tell me.  So you can get the tools 
you need if you can get access to the appropriate hardware.  Its always 
money ... but maybe someone nearby has the box you need, since these power 
workstations are spreading rapidly. 

--
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: gindrup@math.okstate.edu (Eric `'d'kidd' G..)
Subject: Re: My objections to the collapse postulate
Organization: Oklahoma State University, Math Department
Date: Fri, 10 Apr 1992 21:24:04 GMT

Take two observers and a source of photons.  Place all three in deep
space sufficiently shielded so that the effects of the rest of the universe
are unimportant (he says, smilingly..).  Put one observer 3 meters "south"
of the photon source.  Put one observer 4 meters "west" of the source.  
So now we know where everyone is.  Every second, the photon source is made
to give off a photon.  Now either the photon collapses at the first observer,
the second observer, or the rest of the universe (probably the isolation
shielding).  If the photon collapses at the first observer, then the second
observer should be able to determine this fact by observing that he did NOT
observe the photon and the shielding did not observe the photon (detector of
some sort . . . how about a thermometer :-).  Thus the fact that the photon
collapsed at the first observer is NOT discernible before a photon could
travel along the entire surface of the shielding which is SLOWER than a
photon travelling between the two observers.  The information that the second
observer obtains does not travel between observers faster than light, because
the second observer cannot know whether either observer was actually
"there" when the photon collapsed.
Okay, new experiment... Two hemispherical photon-detectors.  Same type of
experiment.  Same result.  Same explanation...
What's the problem?

--Eric Gindrup ! gindrup@hardy.math.okstate.edu
From: jim@cs.UAlberta.CA (Jim Easton)
Subject: Re: Question about dimmer switch and lamp.
Organization: University of Alberta, Edmonton, Canada
Date: Fri, 10 Apr 1992 23:08:13 GMT

siegman@EE.Stanford.EDU (Anthony E. Siegman) writes:

>But can anyone say authoritatively, if you slowly ("adiabatically")
>vary either the current or the voltage applied to a light bulb
>(letting it come to temperature equilibrium at each setting), will
>there be a *true hysteresis*, or a true bistable behavior, in the
>light versus current, or the light versus voltage curves?  

>Or is the hysteresis only in the dimmer-light bulb combination, and
>really more in the dimmer's response to a nonlinear load than to any
>hysteresis in the light bulb itself?  

Yes - the hysteresis is in the combination.  The bulb by itself would
not exhibit a hysteresis behaviour under normal circumstances.
Normal circumstances being constant voltage.  When you first turn
on a bulb the immediate current is very high because the resistance
is very low which means a lot of energy is being dissipated in the
filament.  The filament has a very low thermal capacity and it heats
up rapdily raising the resistance, lowering the current and lowering
the power.  At some point the energy dissipated will equal the energy
radiated and it stabilizes at that point.

With the dimmer in the circuit you have an entirely different situation.
It is closer to being a constant current.  It isn't actually constant 
current but for the sake of argument I am going to call it that.

The energy dissipated in the filament is I**2*R.  So for a given 
current the power is proportional to the resistance.  At low 
temperatures the resistance is low and there isn't enough power
to overcome the heat losses and the temperature stays low.  If
somehow you can heat the filament (momentarily increase the current
or approach this current from the hot side) then the resistance 
increases and power dissipation increases - enough to keep it hot.

I don't have actual numbers for the resistance of a bulb, the
current and the temperature dependence but one could measure them.
You would find that this is indeed a true bistable state.

	Jim
Newsgroups: sci.physics
From: routd@woods.ulowell.edu
Subject: new sci. group on LIQUID CRYSTAL TECHNOLOGY
Organization: University of Lowell
Date: Fri, 17 Apr 1992 01:58:08 GMT

hello netters,
	The aim of this posting is to open a new newsgroup on 
LIQUID CRYSTALS (SCI. LIQUID CRYSTAL TECHNOLOGY). Some times back, I posted
this in the SCI.Engg. and the response was great!
	Liquid Crystals became a subject of multidisciplinary nature and
Physics of Liquid crystals is the foundation stone in order to realise more and
more applications. Again this year, NOBEL prize to Prof. P.G. DeGennes 
is the testimony to this.

The proposed topics that would fall  under this group are:

# Physics and Chemistry of LIquid Crystals

# Liquid Crystal Displays

# Electronics involved in the Display Technology

# Liquid Crystal Polymers, 

# Lyotropic and Bio-polymeric liquid crystals

# Composites based on Liquid Crystals

# Electronic materials involving Liquid Crystals ( Linear and Nonlinear
	optical properties)

# Molecular properties Of Liquid crystals

# Liquid Crystals as the meeting point of almost all the Physical
phenomena, known to us ( e.g., Superconductivity, Ferroelectrics,
Ferromagnetism, Superfluidity, Astropysics, Particle Physics, Fluid flow
 and so on. The list is endless.
	
	Hope this is the begining. Hope also that it will create a lot of 
interest!

Optimistically,

Deeleep K. Rout.
==============================
Routd@woods.ulowell.edu
(508) 934-3712
============================
From: aboulang@bbn.com (Albert Boulanger)
Newsgroups: sci.physics
Subject: Re: van de Graaff generators
Date: 15 Apr 92 11:55:14
Organization: BBN, Cambridge MA
	<1992Apr14.120204.8697@dxcern.cern.ch> <jim.703295980@st-michael>
Reply-To: aboulanger@bbn.com
NNTP-Posting-Host: kariba.bbn.com
In-reply-to: jim@cs.UAlberta.CA's message of 14 Apr 92 23:59:40 GMT

In article <jim.703295980@st-michael> jim@cs.UAlberta.CA (Jim Easton) writes:

   Off hand I would say this is not too practical for you unless you want
   to generate a beam.  The second method involved what we called a
   "generating voltmeter".  This was plate mounted inside the tank 
   facing the terminal.  There was a grounded chopper plate rotating
   in front of it so an AC signal was generated on the plate the amplitude
   of which is proportional to the terminal voltage.  Calibrating this
   voltameter was easy (for us) - we calibrated it from the analysing
   magnet.


To lightning research types this instrument is known as the field
mill. It is a cleaver way of integrating a chopper circuit into the sensor.
It is also used in industry to measure man-made electric field
potentials -- they are used on military helicopters with a high votage
transformer to get the potential of the helicopter equal to the
ground to null-out static buildup. I have seen military surplus units.


Regards,
Albert Boulanger
aboulanger@bbn.com
From: vijay@wiliki.eng.hawaii.edu (Vijay Fafat)
Subject: Right Neutrino
Organization: University of Engineering, College of Engineering
Date: Sat, 11 Apr 1992 07:26:26 GMT


David Brahm wrote the following:

If you give the neutrino a Majorana mass (as is done in the usual see-saw
mechanism), then when you overtake the light left-handed neutrino you will
see a light right-handed antineutrino!  The see-saw theory also contains a
heavy right-handed neutrino and its antiparticle, a heavy left-handed
antineutrino, but these do not appear in your "experiment".

The trick here is that Majorana masses violate any quantum number which the
particle carries (here, e.g., lepton number), so "particle" and
"antiparticle" are not as well-distinguished as we normally imagine.  If
the electron had a Majorana mass (instead of a Dirac mass), lepton number
and electric charge would be violated.

**************

      Now THAT gives rise to something else,David. What would I see if the
same neutrino was AT REST in my frame? Would I see a heavy neutrino ? A light
one? What about its chirality?. At what point in the experiment does the switch 
from left- to right-neutrino occur? Or is it that here too, the ubiquitous
Uncertainty rule comes to the rescue, saying you're not allowed to do this (very
loosely speaking :-)  )?

------ Vijay

Don't blame me for being dumb. It was God's mistake.
From: johncobb@ut-emx.cc.utexas.edu (John W. Cobb)
Newsgroups: sci.physics
Subject: Re: Fusion reactor disasters --- impossible
Keywords: fusion, "meltdown"
Date: 7 Apr 92 16:27:43 GMT
Reply-To: johncobb@ut-emx.cc.utexas.edu (John W. Cobb)
Distribution: na
Organization: The University of Texas at Austin

In article <1992Apr3.194448.21075@cs.rochester.edu>,
dietz@cs.rochester.edu (Paul Dietz) writes:
|>In article <69672@ut-emx.uucp> johncobb@ut-emx.cc.utexas.edu (John W.
Cobb) writes:
|>
|>>|>and I said to that:
|>>|>it would be impossible because the temperature that is needed is to
sustain
|>>|>the reaction is so high that if a "mass" did escape the chamber, it would
|>>|>dissipate and with the momentum it had (if any)  the most damage that
|>>|>would be caused is a hole in the chamber and some nearby jogger
complaining 
|>>|>that someone from the plant is throwing bowling balls at her. 
|>>|>
|>>|>who is right?
|>>|>
|>>
|>>You are.
|>
|>
|>No.  You can compute the "time to meltdown" for a fusion reactor,
|>assuming the first wall is made of a given material, there is a given
|>neutron wall loading during operation, and assuming that when the
|>fusion reaction is terminated, cooling of the first wall is lost.  For
|>bad choices of materials, like aluminum, the first wall melts within
|>minutes due to heat from induced radioactivity.
|>
Correct.

|>Even a little cooling helps, though, and some materials, like silicon
|>carbide, cannot melt even if they are never subsequently cooled.  But,
|>in principle, it is possible to get meltdowns in an improperly
|>designed fusion reactor.
|>
|>	Paul F. Dietz
|>	dietz@cs.rochester.edu
                             
2 notes. 

1) the first attribution (the original question) should be that of the 
   original poster, Francis Godfrey and not me.

2) In the rest of my answer which you did not include in your reply,
   I went on to say, in effect, that you could "screw up the machine"
   in minor ways via controllable or uncontrollable disruptions and 
   you could even screw up in big ways and breach the first wall. One
   way to do it is by melting the first wall as you detailed above (there
   are also others). However, my first point was that this was not a 
   likely occurance (but not impossible). My second and more important
   point was that if it did occur you would not get a Chernobyl-like
   Megacurie radioactivity release. This is what the original poster
   indicated, and if I read between the lines in what you are saying,
   perhaps this is your feeling as well. So it seems we're all pretty
   much in agreement on facts.

Since you are at Rochester, perhaps you could comment on ICF accident
scenarios. Since ICF is pulsed at a few hertz while MFE is continous,
perhaps there is more (or less) problems with thermo-mechanical stresses
on the frist wall, support strucuture, etc.

John W. Cobb
jwc@fusion.ph.utexas.edu
Newsgroups: sci.physics
Subject: mass definition in particle physics
From: kyee@bnlux1.bnl.gov (kenton yee)
Date: 14 Apr 92 20:55:45 GMT
Distribution: na
Organization: Brookhaven National Laboratory, Upton, NY 11973
Keywords: mass, particle physics

In article <22637@dog.ee.lbl.gov> sichase@csa1.lbl.gov writes:
>>>Brahm at Caltech wrote :
>>>Mass is the pole of the propagator. ...
>> 
>I would say that the pole of the propagator is the mass, not the other way
>around.  You write a wave-equation and solve it for the Green's function.  It
>turns out that the propagator has a pole when the particle is on-shell.  
>-Scott

  The advantage of Scott's viewpoint is that it highlights the hidden
  assumption that there is a "particle" to talk about.  For example,
  you cannot prove that the full QED electron satisfies the Dirac
  equation... in perturbation theory one assumes in-out states which
  do, but that's just a working paradigm, probably incorrect.
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Baryon quark idea
Date: 16 Apr 92 20:59:45 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 <16APR199213385899@sscvx1.ssc.gov>, sawyer@sscvx1.ssc.gov (Lee Sawyer) writes...

> The two most important experimental inputs for the color quantum number
>are the antisymmetric baryon wavefunctions for, e.g. the omega; and the "color
>factor" in e+e- --> q \bar{q} which is needed to match the predicted and
>measured cross sections. Coupled with recent LEP results * which show that
>Abelian couplings are excluded by 5 standard deviations, and you are left
>with some very narrow hoops for any new theory to jump through.
> 

There is also new data from several of the LEP experiments on the spin
of the gluon.  By studying the energy distribution of individual jets in 3-jet
events, they show clearly that the gluon is spin-1 and that, for example,
scalar gluons (spin-0) are completely ruled out.  To do this, they rely on the
fact that the third jet comes from either initial- or final-state gluon 
radiation, so that such events carry information about the gluon.  

So any rival theory must include a self-interacting (non-abelian) vector octet
of gauge bosons mediating the color force.  So whatever it is, it will look 
one heck of a lot like QCD.

-Scott

--------------------
Scott I. Chase
SICHASE@CSA2.LBL.GOV

Newsgroups: sci.physics
From: jcl4@cec1.wustl.edu (Jeffrey C Lerman)
Subject: stepped leaders/long sparks
Summary: Mechanism for stepped leaders (in long sparks/lightning)?
Keywords: spark electrostatic discharge gas breakdown lightning stepped leader 
Organization: Washington University, St. Louis Mo.
Date: Mon, 13 Apr 1992 04:18:01 GMT


Does anyone know anything about the so-called "stepped leader" phenomenon
found in lightning?  This is a process by which the leader of lightning (or
many other gas discharges, but not all) progresses by apparent "steps", each
of which is separated from the next by enough time to justify it being called
a step.  

I am trying to program a mathematical/theoretical model of this process which 
I have found in the literature.  The model originally was intended to explain
the stepping found in long sparks in the laboratory, esp. discgharges through
air of high humidity ( <10 g/cm3 of H2O).  I would like to apply it to
the conditions found in certain types of cloud-to ground lightning, but I
need some help working with the model itself.  I am also
not sure f the theory which the model is based on is still current.

Anyone?

--Jeff Lerman
  student, Washington UNiversity, St. Louis
  314-935-1539
  jcl4@cec1.wustl.edu 
Newsgroups: sci.physics
From: platt@watson.ibm.com (Daniel E. Platt)
Subject: Re: Heard of VIRTUAL PARTICLES???
Date: Fri, 10 Apr 1992 14:45:10 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
Organization: IBM T.J. Watson Research Center

In article <1992Apr9.233448.1@acad2.alaska.edu>, assib@acad2.alaska.edu writes:
|> The other day a friend of mine mentioned 'Virtual Particles...'
|> Could I get some more info on this?
|> 
|> If you have any feedback, send to:
|> ----------------------------------
|>       ASSIB@ACAD2.ALASKA.EDU

In Quantum Mechanics, you can compute transfer matrices from which
cross-sections come out, by doing a perturbation expansion about a
known solution.  That expansion looks sort of like a power series in
the perturbation Hamiltonian.  

In 'Second Quantization,' particles are treated like quantum
excitations in a field (ground state = vacuum, 1st excitation = 1
particle, 2nd excitation = 2 particles); the excitations obey
statistics (Fermi or Bose), and preserve the idea that particles have
no identity.  The formulation looks like raising and lowering operators
for the harmonic oscillator; particles can be 'created' or 'destroyed'
using the raising and lowering operator.  The Hamiltonian is written in
terms of the 'number' operator -- which is just the product of the
creation and destruction operators.

If you want to apply perturbation expansions to the scattering of
electrons from each other via the photon field, terms emerge that allow
the creation and destruction of electron-positron pairs from the
photonic interactions -- even if the energy isn't enough to create a
real pair, the terms do make contributions to the cross-section (sort
of a 2nd quantization version of tunneling -- very crudely).  Those
terms contribute to the self-energy, as well.  In a way, electrons are
never 'bare;' they are always in interaction with a photon field that
includes contributions from this kind of perturbation.  Reformulating
the effective mass and charge in terms of these contributions is called
renormalization; the effect is to 'dress' the 'bare' electron.


Dan