HDTenEightyP/NetNews huggingface dataset:
From: wellison@kuhub.cc.ukans.edu
Newsgroups: sci.physics
Subject: Laser Mania: Laser for sell
Date: 26 Jan 93 15:32:02 GMT
Article-I.D.: kuhub.1993Jan26.093203.46771
Organization: University of Kansas Academic Computing Services



Got some different HeNe modules this time. These are idenical to the other
modules but produce 1.2mW to 1.5mW output. They also have the 
intergrated high voltage power supply that runs off of +12vdc. However, these
are multimode which means they have a wide beam. The beam can be narrowed down
with a minus lense though. Also, the side is milled out of the housing so that
the lasing action inside the plasma tube can be seen. These are great lasers
for teaching or training purposes. Due to the wide beam output, I am selling
these for $30 each plus 5$ shipping. 

I also scrounged a Spectra Physics model 124 HeNe laser and power supply. The
laser was manufactured in 1981, but the tube was re-gassed in 1991. It is in
excellent condition and produces +19mW. I am asking $2,000 or best offer plus
shipping.

For those interested in agron lasers, I have aquired two American 60X
multi-line heads. They produce about 80mW each in 488Nm to 514Nm (blue/green).
I am selling the heads for $1000 each. But, just for your info, Meredith
Instruments has Cyonics model 2201 argon lasers with power supplies that
produce 25mW blue only (488Nm) for $1200. They are selling the head for $695
(I'm thinking about one of those myself ;-) Thier address is:

Meredith Instruments
P.O. Box 1724
5035 N. 55th Ave
Glendale, AZ 85301
1-602-934-9387

In case anyone is wondering, I'm not making a profit on these lasers. I'm a
laser fanatic and I know there are others out there like me. I sell them for
what I paid for them to pass the saving on to you. Nothing I hate more than the
surplus dealers ripping people off with a cost to you of 2 or 3 times of what
they paid for it. Through years of beating the bushes, I have found out where
and how these guys get thier lasers. I'm paying the price they pay for them,
then pass that cost on, nothing more. If you have a specific laser need, let me
know and I will try to get the best price I can for you (definetly less than
what the surplus markets what for them).

-=-= Wes =-=-
Newsgroups: sci.physics
Subject: Re: What causes electrical shock?
From: mcirvin@husc8.harvard.edu (Matt McIrvin)
Date: 22 Jan 93 01:10:39 GMT

djclute@cwis.unomaha.edu (Daniel Jonathan Clute) writes:

>Vacation over, I'm still seeking the answers to two particular questions:
>1) what causes static shock (low humidity?), and 2) what is the proper
>technique to "ground out" (rub on wood?).

Static charges tend to build up in conditions of low humidity because
dry air is a better insulator; moist air will carry charges off of the
surfaces of objects to restore neutrality.  As for what causes the
charge to build up when you rub against things like shag carpets, I
believe that that subject, after millenia of observations, is still
quite poorly understood.

Touching a big wooden object might work well as a means of grounding,
since it's likely to possess less surface charge than you do (big
wooden objects don't shuffle around on rugs) and will carry the charge
away slowly so you don't get zapped.  A more spectacular means is to
carry around something made of metal and touch doorknobs, faucets,
etc.  with that first.  The spark will jump, but you won't feel it
because the current is flowing through the area of contact between
your hand and the metal rather than jumping across a gap from a small
spot on your finger.

-- 
Matt McIrvin
Newsgroups: sci.physics
From: wellison@kuhub.cc.ukans.edu
Newsgroups: sci.physics
Subject: Mother of all HeNe's for sell
Date: 28 Jan 93 18:27:09 GMT
Organization: University of Kansas Academic Computing Services


I just got a lead on the mother of all HeNe's. This guy is a Jodon
HN-50 producing +50mW ! ! The tube was replaced in 1989 and it has
very low hours on it. The laser comes with a Jodon digital power meter
and the power supply as well. The cavity has an etalon prism for tuning
in the 1192Nm and 3390Nm (IR) range. It is also open cavity design.
The overall unit is in excellent condition. The guy wants $4,000 or
best offer for it. The ultimate light show or holography laser !

-=-= Wes =-=-
Newsgroups: sci.physics
From: dedmunds@selkirk.sfu.ca (Darran Edmundson)
Subject: Re: A Good Stat. Mech. Book Is Hard To Find
Organization: Simon Fraser University, Burnaby, B.C., Canada
Date: Sun, 24 Jan 1993 18:30:24 GMT

I really enjoy Lucy Reichl's "A Modern Course in Statistical Physics."
It's comprehensive and extremely well written, a rarity in physics texts.

Regards,

-- 

Darran Edmundson
dedmunds@sfu.ca

From: selee@hpcc01.corp.hp.com (Lee Say Eng)
Date: Fri, 22 Jan 1993 03:18:06 GMT
Subject: Luminous Intensity
Organization: the HP Corporate notes server
Newsgroups: sci.physics


If two light rays of luminous intensities  I_1 and I_2 are in the
same direction and are a small distance x apart,  what would be the
apparent total intensity to an observer a long distance away?

Is it simply   I_total = I_1 + I_2  ?


(Ignoring losses in intensity as the light rays traverses thru space)




Thanks.


ALAN PHANG

alan@hpmalr50.mal.hp.com

---
Newsgroups: sci.physics
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: integrity and competence of moderators
Organization: University of Virginia
Date: Thu, 21 Jan 1993 20:54:41 GMT

In article <C1807M.DGq@well.sf.ca.us> sarfatti@well.sf.ca.us (Jack Sarfatti) writes:
>
>OK, perhaps, insistence on Ph.D. may not be necessary. For example,
>Aephraim Steinberg does not yet have his Ph.D. - but he would be well
>qualifed to be a moderator. He is definitely competent. He is always
>polite and fair in the best spirit of science.
>
>I doubt that men of the stature of Yakir Aharonov, Steven Weinberg etc.
>would allow themsevles to be moderated by the present slate of moderators.
>If the whole point is to get men of that staure to contribute, then
>you must have a prestigious set of moderators. As it is the present fact
>is that the moderated conference will be a power trip for Bass et-al.

     Since things like this have come up before, against my better
     judgment I'll respond.  

     Moderating a Usenet newsgroup is *no* power trip.  It
     requires substantial continuous work, and there is little return
     on the investment of time.  One would have to be a complete
     idiot to consider moderating a Usenet newsgroup because of the
     'power' it offered.

                           dale bass


-- 
C. R. Bass                                          crb7q@virginia.edu        
Department of Mechanical, 
     Aerospace and Nuclear Engineering
University of Virginia                              (804) 924-7926
Newsgroups: sci.physics
From: schumach@convex.com (Richard A. Schumacher)
Subject: Re: Big Bang Alternates
Date: Fri, 22 Jan 1993 02:10:52 GMT
Organization: Engineering, CONVEX Computer Corp., Richardson, Tx., USA
X-Disclaimer: This message was written by a user at CONVEX Computer
              Corp. The opinions expressed are those of the user and
              not necessarily those of CONVEX.

In <1736.289.uupcb@nitelog.com> bruce.weaver@nitelog.com (Bruce Weaver)  writes:

>Basically, it is a feedback cycle that acts as a thermostat to maintain
>the temperature of the Universe at 3 degrees.  Like Chip Arp and his
>statistical associations of QSOs and low redshift galaxies, this idea
>gored a lot of oxes.  It was their computer modeling of the processes

Care to comment on the likelihood that this mechanism would yield
a radiation field uniform to 1 part in 100,000?



>If one could make sense of Arp's observations/statistics (mostly, I
>think, the problem lies in the lack of blue shifts), then these two
>parts raise doubts about the Big Bang.  If Arp were right, then the

This sounds a little like saying that creationism would be in pretty
good shape, if we could just reorder the fossil record and get
all those pesky radiometric dates to come in under 10,000 years...
It won't wash. Given the lack of a velocity-independent explanation
for redshift, the total absence of blueshifts outside the Local
Group damns any steady-state theory. 

As for scientific political correctness: at what point does heterodoxy
become incompetence? The steady state people are pretty close to
crossing the line, IMHO.
From: sawyer@utahep.uta.edu (Lee Sawyer)
Newsgroups: sci.physics
Subject: Re: "Feynman Diagrams"
Date: 27 Jan 93 22:02:00 GMT
Organization: University of Texas at Arlington High Energy Physics Group
News-Software: VAX/VMS VNEWS 1.41

In article <1k6k74INNi8u@serv-200.dfki.uni-kl.de>, klauck@dfki.uni-kl.de (Christoph Klauck) writes...
>Hi everybody,
>I am searching for a program to draw "Feynman Diagrams" and
>some introduction on how to use it.
>Thanks in advance
>	Christoph Klauck

  If you use LaTex, there is a very nice package of Feynmann graph 
macros called "Feyngraph". It is available from CERN I believe.
I tried to find my notes on the package, to at least give proper
credit to it's author, but to my horror I have misplaced them.
However, the package is described in a Comm. Comp. Phys. article
from a few years back (1989 I believe).

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

         Dept of Physics                          
         Univ. of Texas                            
               at Arlington
From: brahm@cco.caltech.edu (David E. Brahm)
Newsgroups: sci.physics
Subject: Re: Home made monopoles
Summary: A general rule about stability, and how to violate it
Date: 27 Jan 93 23:31:57 GMT
Organization: California Institute of Technology, Pasadena
NNTP-Posting-Host: punisher.caltech.edu

John.Brawley@p1.f9.n8012.z86.toadnet.org (John Brawley) writes:
> ...I wanted to make a "floating ball" that sat in a concave all-(south or
> north) "dish" shaped field (no problem), and had all the outside of the
> sphere the same polarity.  I wasn't trying to make a monopole...

You not only wanted to make a monopole (the sphere), you wanted to make a
("dish-shaped") field in which all field lines converged to a stable point
without putting a source at that point!  You can't do that even with
electric fields (or electric fields plus gravity).  Gauss's Law(s)
generically disallow any such static "floating" constructions, to wit:
| (*1*) No static (electro-magnetic-gravitational) field configuration |
|       in empty space will hold an object in stable equilibrium.      |

Yet, almost the very object you describe, a "floating globe", is sold in
novelty stores (for $200 or so).  The clever designers used non-static
fields, which get feedback from the globe's position.  Also, a magnet will
float stably above a superconductor, which somehow manages to pull the same
stunt automatically, without any clever designers.

Here's my question, then:  Put an electron in a bowl; by (*1*) there is no
point where it can sit stably, i.e. del.(qE+mg)=0 everywhere.  Yet I think
it just sits there anyway (?).  Furthermore, a book is just a collection
of nucleons and electrons; it floats stably a few Angstroms above my desk,
no problem.  Where does (*1*) break down?  Is QM at work here?

--
Staccato signals of constant information,  |  David Brahm, physicist
A loose affiliation of millionaires and    |  (brahm@cco.caltech.edu)
  billionaires and Baby ...                |---- Carpe Post Meridiem! --
These are the days of miracle and wonder,  | Disclaimer:  I only speak
And don't cry, Baby, don't cry, don't cry. |   for the sensible folks.
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Warping???
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Tue, 26 Jan 93 20:25:31 GMT

Hinson writes:

Now I introduce you to an important postulate that leads to the 
concept of relativity that we have today.  I believe it will seem quite 
reasonable.  I state it as it appears in a physics book by Serway: "the 
laws of physics are the same in every inertial frame of reference."  
What it means is that if you observer any physical laws for a given 
situation in your frame of reference, then an observer in a reference 
frame moving with a constant velocity with respect to you should also 
agree that those physical laws apply to that situation.  

---
This principle also holds in the classical mechanics of point particles,
so it is NOT enough to assume this principle to get special relativity.
In fact, classical mechanics satisfies what is known as "Galilean
relativity" in which the Galilei group replaces the Poincare group.  It
is the *combination* of this principle with the fact that light is
observed to have the same velocity in every inertial frame that gets us
special relativity.  (It would be consistent with classical mechanics if
light always travelled at the same speed *in the rest frame of its
source*, and then laws would look the same in every inertial frame, but
light emitted from a source movig relative to you would appear to have
a different velocity.)  This point is always mentioned in careful
discussions of special relativity; the seeming contradiction between TWO
principles is what pushed Einstein to discover that the symmetry group
of the world was not the Galilei group but the Poincare group.
From: mcirvin@husc8.harvard.edu (Matt McIrvin)
Newsgroups: sci.physics
Subject: Re: gravitons
Date: 26 Jan 93 00:49:17 GMT
Article-I.D.: husc.mcirvin.728009357

DTC3@psuvm.psu.edu writes:

>In any event, a prime assertion of General Relativity is that gravity
>is *not a force*, but a characteristic of the geometry of spacetime;
>it seems, then, that the notion of a force propagator (the graviton)
>moving about in spacetime is not consistent with this assertion.

Gravitons are speculative, but in attempts so far to quantize gravity
it doesn't matter that gravity is not a force in the usual sense: the
gravitons are quantized vibrations in spacetime geometry, and a field
made of virtual gravitons would (in the limit of large numbers) presumably
look like an ordinary distortion in spacetime.  The major problem is
that if you try the kind of approach to quantization that is used for
other theories, you find that the infinities that arise in quantum
field theories can't be handled in the usual way.  This seems to
imply that whatever does work, it's not the usual approach where
you calculate things perturbatively using Feynman diagrams.  So in
that sense it probably won't make sense to talk about things being
scattered by virtual gravitons. 

The difficulty, though, is *not* the geometric nature of the theory,
in and of itself.  Classical electromagnetism is equivalent to a theory 
in which the "force" is a similar geometric effect, operating on a five-
dimensional spacetime where the fifth dimension is curled up into a
little circle; objects spiral around the resulting "tube" at angles
dependent on their charges, and the geometry of five-dimensional spacetime
makes them veer about.  (This isn't quite Kaluza-Klein theory--
you get that when you say additionally that the dynamics of the
spacetime itself are given by a generalization of the Einstein 
equation to five dimensions.  Here I'm just speaking of Maxwell
electromagnetism as something called a "U(1) principal bundle.") 

Yet electromagnetism can be quantized and the "force" described as due
to virtual photons.  In fact, the geometric picture then becomes a nice 
way to visualize gauge symmetry. 

>  And
>as there are  no   direct experimental data regarding the behavior of
>gravity at the quantum level, can the existence of a neutral, massless,
>spin-2 graviton be justified on symmetry grounds alone?

Well, maybe.  Basically, if quantum gravity acts even vaguely like
any other quantum field theory, that's what the graviton ought to be
like based on symmetry arguments and the properties of general
relativity.  But nobody really knows if this is really the case.

(And I don't feel qualified to say much more about this, seeing as I've
already screwed up one factual statement about massless propagators...)
-- 
Matt McIrvin
From: steinly@topaz.ucsc.edu (Steinn Sigurdsson)
Newsgroups: sci.physics
Subject: Re: Black hole insights
Date: 26 Jan 93 10:40:15
Organization: Lick Observatory/UCO
NNTP-Posting-Host: topaz.ucsc.edu
In-reply-to: bbowen@megatest.com's message of Mon, 25 Jan 1993 17:49:50 GMT

In article <C1F85w.Fx0@megatest.com> bbowen@megatest.com (Bruce Bowen) writes:

   From article <STEINLY.93Jan24151539@topaz.ucsc.edu>, by steinly@topaz.ucsc.edu (Steinn Sigurdsson):
   > I think it is very important to forget about "test" particles being
   > sent in carrying no mass-energy, if you want to track the fate of the
   > particle it has to carry _finite_ energy. Yet again QM comes to the
   > rescue of GR!

     "Infinitesimal" does not mean "zero".  It means the object's mass/energy is so small
   compared to the system that it's contribution can be ignored.  A 10 ev photon falling
   into a galactic size black hole can pretty much be treated as an infinitesimal.

Yes, I know. However, it is sometimes important to look at the
behaviour of infinitesimals as you take the value to zero.
I contend that in the black hole case the formal limit becomes 
unphysical - the explicit question is what does a stationary observer
at infinity _see_ as the test particle approaches the horizon.
I contend that that requires a strictly finite amount of energy
as you must not only emit a signal but it must exceed the local
thermal noise which is ultimately dominated by the Haking radiation
from the black hole itself and inversely proportional to the mass (to
some power) - incidentally the lifetime of the black hole is also
longer for higher mass, so for fixed mass test particle we expect
to follow it closer to the horizon and thus for a longer "external"
time, but that is ok because the evaporation time is correspondingly
longer.
	Thus the ultimate resolution of the problem, I contend, is
always that the horizon stretches over the particle before "external"
time approaches the black hole evaporation time if the particle
carries enough energy that we can continue observing it that close to
the horizon.

*  Steinn Sigurdsson   			Lick Observatory      	*
*  steinly@lick.ucsc.edu		"standard disclaimer"  	*
*  The laws of gravity are very,very strict			*
*  And you're just bending them for your own benefit - B.B. 1988*
Newsgroups: sci.physics
From: mkagalen@lynx.dac.northeastern.edu (michael kagalenko)
Subject: Re: ATOMS & ELECTRONS
Organization: Northeastern University, Boston, MA. 02115, USA
Date: Sat, 23 Jan 1993 22:01:38 GMT

In article <1jipr8INN9vo@elroy.jpl.nasa.gov> angelyn@fridge.Jpl.Nasa.Gov (Angelyn P. Williams) writes:
>In article <1993Jan19.203435.9707@sfu.ca> Leigh Palmer, palmer@sfu.ca writes:
>
>>In article <16302@hq.hq.af.mil> John C Pope, jpope@pafosu1.hq.af.mil
>>writes:
>
>>>  *   Why do the elctrons (of an atom) not go crashing into the protons?
>
>>John, no one knows the answer to that question. The field of quantum
>>physics is founded in the empirical observation that they do not. There
>>is a name for the non-event, by the way. The crashing of electrons into
>>their nuclei is called the "Ultraviolet Catastrophe #2".

You don't think that renormalization is an  answer to UVcatastrophy, Leigh ?

>

>
>H = (p^2/(2m)) + e^2/r                  Hamiltonian, more or less,
>                                        for hydrogen atom
>
>E1 = <H>                                Expectation value of Hamiltonian
>                                        gives ground state energy
>
>   = <(p^2/(2m)) + e^2/a>               Say ground state atom has typical
>                                        radius a
>
>(Delta-p)(Delta-x) > hbar               Heisenberg uncertainty principle
>
>--> Delta-p > hbar/a                    uncertainty in radius on the 
>                                        order of radius itself (a)
>
><p^2> = (Delta-p)^2+<p>^2                  
>      = (Delta-p)^2                     <p>=0 (ground st = energy eigenst)
>      > (hbar/a)^2
>
>So E1 > (hbar^2/(2ma^2)) - e^2/a        Quantum-mechanical gnd st energy
>--------------------------------
>
>Looky here.  Classically John was right, the electron should
>stick to the proton "like a magnet to metal,"  and why? because the classical
>energy -e^2/r gets smaller and smaller as r -> 0.  But look at E1 here
>(quantum-ly).  Sure -e^2/a gets smaller, but the kinetic energy part
>hbar^2/(2ma^2) gets bigger, faster!  So as the electron gets infinitesmally
>close to the proton, you have an extermely large amount of kinetic, and 
>therefore total energy.  Hence it does not happen.  One may say the 
>non-collapse of the hydrogen atom is "caused by" the large momentum uncertainty
>when an electron is confined to a tiny tiny position uncertainty.  So why
>does a magnet get as close as it can to a refrigerator door yet an electron
>is compelled to stay a bit away from a proton?  Classical scale (big) vs.
>quantum scale (tiny).

Why Earth is not crushing into the Sun ? Your answer really applys to
the question "Why electron in the ground state doesn't radiate"  








Newsgroups: sci.physics
From: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: Fan mail.
Organization: Whole Earth 'Lectronic Link
Date: Wed, 27 Jan 1993 19:00:45 GMT


From pbhya!gdridle@PacBell.COM Wed Jan 27 08:31:12 1993
Date: Wed, 27 Jan 93 08:32:13 PST
From: pbhya!gdridle@ns.PacBell.COM
To: sarfatti@well.sf.ca.us
Subject: Re: New Physics, Healing, Paranormal
Newsgroups: sci.physics,sci.skeptic,alt.paranormal,alt.sci.physics.new-
theories,

rec.arts.startrek.tech
Organization: Pacific * Bell, San Ramon, CA
Cc:

Please see a psychiatrist, or get an education.  At the very least, keep
your bullshit out of sci.physics, you idiot.  Thank you.

Guy Ridley

& r
To: sarfatti@well.sf.ca.us pbhya!gdridle@ns.PacBell.COM
Subject: Re: New Physics, Healing, Paranormal

It takes one to know one.
Newsgroups: sci.physics
From: frisinv@alleg.edu (Vincent Frisina)
Subject: Re: Relativity book for a 9 year old
Organization: Allegheny College
Date: Tue, 26 Jan 1993 21:29:16 GMT

In article <1993Jan24.185404.6715@noose.ecn.purdue.edu>  
muttiah@thistle.ecn.purdue.edu (Ranjan S Muttiah) writes:
> 
> Are there any relativity book(s) that a nine year old could read ?
> I haven't been through any of Gamow's Mr. Tomkin books, but I think they 
> might be a little too much for a child of that age.  A book that
> illustrates relativity in cartoon form would be nice.
> 
> Please email.

My parents gave me a text written by Einstein himself on the subject when  
I was that age. What little there was that was not within my immediate  
grasp, was clear after a trip to public library. The book was tilted  
simply Relativity. 
--
Vincent Frisina
Email: frisinv@alleg.edu