HDTenEightyP/NetNews huggingface dataset:
From: merritt@macro.bu.edu (Sean Merritt)
Newsgroups: sci.physics
Subject: Re: Magnetic monopoles?
Date: 25 Jan 93 20:05:07 GMT
	<1993Jan20.025101.9082@CSD-NewsHost.Stanford.EDU>
	<25404@galaxy.ucr.edu>
Organization: Boston University Physics Department
In-reply-to: baez@guitar.ucr.edu's message of 25 Jan 93 03:36:12 GMT


 
In article <25404@galaxy.ucr.edu> baez@guitar.ucr.edu (john baez) writes:


   In article <1993Jan20.025101.9082@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
   >If there are no monopoles then searching for them would indeed be
   >pointless.  But if charge quantization only increases the known lower
   >bound on the number of monopoles in the universe by one, why should the
   >knowledge that charge is quantized change our mind about searching for
   >them?  (Not objecting, just want to learn how to think like an
   >experimentalist.  :-)

#   For starters, you are being way too logical.  It goes like this:
#   monopoles would explain charge quantization, which is otherwise
#   not easy to explain.  So let's look for monopoles!  

The percipitating factor for the new searches was more due to the fact
that theorist found that monopoles "appeared" in GUT's. I think it
was in 1974, (for example see G. t'Hooft, Nucl. Phys. B, 79, 276 (1974)) 
that the subject heated up again. Although there has been a steady
stream of papers dating back to 1931, by both theorist and experimentalist.
The list reads like a "Who's Who" of physics(Alvarez,Bohm,Aharonov,Schwinger
Weinberg,Cabibbo,Berry(the phase guy),Kittlel,Drell,Rubbia, among others
and of course Dirac).

The interest is wide and varied. Berry for example showed that there
is a geometrical phase factor associated with an electron in the
field of a monopole.

I still think that the fact that they would add symmetry to Maxwell's
equations is a valid reason for the searches.


-sjm

--
Sean J. Merritt		         |"Road-kill has it's seasons just like     
Dept of Physics Boston University|anything, there's possums in the autumn  
merritt@macro.bu.edu             |and farm cats in the spring." T. Waits
From: John.Brawley@p1.f9.n8012.z86.toadnet.org (John Brawley)
Sender: fredgate@cheswicks.toadnet.org
Newsgroups: sci.physics
Subject: Home made monopoles
Date: Tue, 26 Jan 1993 22:29:20 -0600

 A > From: brahm@cco.caltech.edu (David E. Brahm)
 A > Organization: California Institute of Technology, Pasadena

 A > >                     Home made magnetic monopoles
 A > > [Glue together 2 hemispheres each magnetized with "North" at its
 A > pole]
 A > 
 A > I don't know who's serious and who's joking here, but for the record,
 A > Adams's construction is not a monopole (I believe it's a quadrupole).
 A > Field lines outside the sphere emerge from each pole and re-enter at
 A > the
 A > equator; "glue" doesn't stop them!  You can't make something that
 A > violates
 A > Gauss's Law of Magnetism (del.B=0) by superposing things that obey it.

This mean you cannot make one of these no matter what?  (of -course-
that's what you mean....  It just seems like it ought to work, say, if
you provided serrated (as in rabbeted) perimeter edges...  You mean
that no matter how tight you make the seams, the field would "leak"
through the (say, nanometer wide) join line?  What would happen to
the sphere _if_, say, you managed to get a perfect join (theoretically
speaking)?  Would the field "leak" through somwhere else?  Metal
fatigue and shatter? What? What?  (I'd thought on this idea several
years ago...  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, just a neat thing with earth's geographical
features painted on it.  Floating like that, tiny breezes ought to
trun it.  Now here you come poking terrible holes in my neat little
floating globe idea!  Gad.  <grin>  Tell me:  what if I drilled tiny
holes all over it?  Would that allow me to have, say 95% of the outer
surface all one polarity, with the other polarity's flux lines all
bunched together in the holes, like they do in a ring magnet?

Direct Email:
john.brawley@f9.n8012.z86.toadnet.org

FIDONet: John Brawley, 1:100/435
PO Box 224, Eureka, MO, 63025-1134
Data (BBMsgSys) (314) 938 5285

"Sit down before Fact like a little child...."
                        --T.H. Huxley
From: harrison@cs.ubc.ca (James Harrison)
Newsgroups: sci.physics
Subject: Statics question (forces, moments...)
Date: 21 Jan 1993 22:55:47 -0800
Organization: Computer Science, University of B.C., Vancouver, B.C., Canada
Distribution: world
NNTP-Posting-Host: shiner.cs.ubc.ca

My apologies if this isn't the correct place to ask this, but I've
been racking my brain over this one for a while now:

I'm trying to modeling a "clock" spring that provides a Moment of
force through it's axis that is proportional to its radial "winding":

M= K(theta-rested - theta)

Where is K is in Newton Meter / Radians.  So as the spring is wound, it
provides a restoring force.  Still with me?  

So attach a long "massless" rod that pivots freely about the axis of the
spring, and has a force applied to the end of it.  The moment of the force
about the axis of the spring is M = r X F, where `X' is the cross product 
between the two vectors r and F.

Now to the simulation, take M, calculate the radial displacement, rotate the
rod by a fraction of this amount to keep everything "accurate", iterate
on the new force F that may now exist.  So that all works.

So now I have a wound spring, I can calculate the Moment of the spring,
and using ||M|| = ||r|| ||F||, I can calculate the magnitude of a transverse
force that must be applied to the rod at a distance r from the axis to 
keep the spring wound.

But I'd really like to have an inverse to the original M = r X F, to 
calculate the 3-space components of the force F, so that I can sum all of
the forces applied to the end of the rod, and go from there.  For
example if I had the same point connected to two of these rod-spring
systems, I would want to iterate the system until it relaxed to its
static configuration.  That is one spring's moment, is another spring's
force (well kind of..).

Ultimately, I even want the rods to be linear springs.  This means
that the length of the rod will change, and it will be necessary to
calculate the transverse force created by a radial spring, it won't be
enough to keep a copy of the old transverse force used to calculate
the winding of the spring.  (If you haven't realized it I'm building a
model of _thin_ deformable surfaces, but I'm not interested in FEMs.)

I know that I can't just try to solve for the XYZ components of F from
M = r X F, because the matrix formed by the cross product is linearily
dependent.  Is there a simple way around this?  I also know that if F
and M are orthogonal, then one can be "replaced" with the other.

Have I missed something?   Do I have to calculate the XYZ components of 
F by using the fact that M and r are orthogonal, and that r and F are
in the same plane, so that F is orthogonal to M also?

I really want a quick equation (or set of...) that takes the _vectors_ M
and r, and gives me the _vector_ F.  Any pointers?

Thanks in advance, 
James
-- 
-------------------------------------------------------------------------------
James Harrison@cs.ubc.ca           `RPCing as fast as the network will let me.'
From: norm@inqmind.bison.mb.ca (Norman P. Paterson)
Newsgroups: sci.physics
Subject: Turbine compressor
Date: Wed, 20 Jan 93 22:13:20 CST
Organization: The Inquiring Mind BBS  1 204 488-1607

This is a little off topic, but somewhat related to physics (what 
isn't?).  I just came up with the idea of using highly compressed gas or 
air for use as a propulsion/attitude control system on airships.  I 
thought that a motor such as found on turbo-prop aircraft might be the 
ideal powerplant.  Have any of you heard of such engines being rigged up 
to compressors (i.e. turbine compressor)?  Or if such a monster does not 
exsist, tell me about the most powerful, lightweight compressors you may 
know of.
        Thanks, 
Norman Paterson
PATERSON AEROSPACE CO.
92 Walnut St.
Winnipeg, MB CANADA  R3G 1N8 (204)786-2192

norm@inqmind.bison.mb.ca
The Inquiring Mind BBS, Winnipeg, Manitoba  204 488-1607
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Newsgroups: sci.physics
Subject: Re: Black hole insights
Date: 25 Jan 1993 20:29 CST
Organization: Texas A&M University, Academic Computing Services
Distribution: world
NNTP-Posting-Host: zeus.tamu.edu
News-Software: VAX/VMS VNEWS 1.41    

mcirvin@husc8.harvard.edu (Matt McIrvin) writes...
>Now, what *I'm* confused about is the situation in which the object has
>a finite mass.  I agree that the horizon will come out to meet the object
>and engulf it, but does this mean the observer will see it wink out
>abruptly?  Forget "coordinate time"-- that's by definition dependent on an
>arbitrary definition.  What do the future light cones do?

They follow the horizon. This follows from the definition of the event
horizon. It is the surface on which a photon will never escape nor ever
fall in. (If it's aimed properly)

Dave Ring
dwr2560@zeus.tamu.edu
Newsgroups: sci.physics
From: metares@well.sf.ca.us (Tom Van Flandern)
Subject: Re: Big Bang Alternates
Organization: Whole Earth 'Lectronic Link
Date: Fri, 22 Jan 1993 16:12:28 GMT


schumach@convex.com (Richard A. Schumacher) writes:

> Given the lack of a velocity-independent explanation for redshift, the
> total absence of blueshifts outside the Local Group damns any
> steady-state theory.

     I'm not arguing for SS, but just commenting on your statements about
redshift mechanisms and blueshifts.

     Velocity is a redshift-blueshift mechanism.  Other mechanisms are
redshift-only.  Examples are tired light and gravitational redshifts.
Several redshift-only mechanisms work very well for alternate cosmologies.

     A. Ghosh lists 20 non-velocity redshift mechanisms in Table 1 of his
paper, "Velocity-dependent inertial induction: a possible tired-light
mechansim," Apeiron 1, #9-10, pp. 35-44 (1991).  These have been proposed
by different authors from 1917 to 1986, starting with Einstein.  A few more
have appeared in the past three years.

     The best known of these is "tired light."  Basically, anything that
causes energy loss to the photons as they travel through space produces a
redshift.  Feynman made a general argument against tired light theories
(before "dark matter" was hypothesized) that is still quoted.  He said that
if the photons encounter any known quantum particles, they will be
deflected enough that images of distant galaxies must arrive fuzzy, not
sharp, due to the slight scattering of their photons that produces their
redshift.

     Today, I think no one would make such an argument in the face of
evidence that dark matter (the dominant ingredient of the universe in the
big bang theory) is still unidentified.  All that is needed to overcome
Feynman's argument is resisting entities individually so small that the
energy loss to photons is smooth and continuous, not in discrete collision
events with quantum-sized particles.  Dark matter is perfectly capable of
making tired light the theory of choice for the cosmological redshift
mechanism.  -|Tom|-

-- 
Tom Van Flandern / Washington, DC / metares@well.sf.ca.us
Meta Research was founded to foster research into ideas not otherwise
supported because they conflict with mainstream theories in Astronomy.
Newsgroups: sci.physics
From: sawyer@utahep.uta.edu (Lee Sawyer)
Subject: Re: female mentors in science
News-Software: VAX/VMS VNEWS 1.41    
Organization: University of Texas at Arlington High Energy Physics Group
Date: Wed, 27 Jan 1993 15:28:00 GMT

In article <1993Jan26.230411.3123@lynx.dac.northeastern.edu>, mkagalen@lynx.dac.northeastern.edu (michael kagalenko) writes...
>In article <1993Jan26.185720.8055@netcom.com> barinaga@netcom.com (Marcia Barinaga) writes:
>>I am a reporter with Science magazine, and am preparing articles
>>for an upcoming special news section on women in science. 
>>
>>I am looking for an example of a female scientist who has left 
>>her mark on a field by attracting, inspiring and training female 
>>scientists. I have heard that in some fields, particularly those 
>>              .......................
>>Also, for a related article in the same issue, I am seeking
>>comments from both male and female scientists on the 
>>question of whether women approach science differently than
>>men. I know this is a controversial question, and am hoping
>>to present a range of views on it. Do women have different 
>>styles of conducting science, or even different intellectual 
>>approaches that may enrich their fields either through 
>>added diversity, or as an example men might learn from?
>>
>All this talk about "female science" looks suspiciously similar to 
>other well known distinctions : "Ariahn" vs "Non-Ariahn", "proletarian"
>vs "bourgeous" science....
> 

 Come now, in the first place I do not believe she used the expression
"female science", and in the second, she is simply testing a widespread
belief - that for whatever reason (evolution, hormones, societal
pressures) women approach problem solving in a "different" manner than
men. I am not sure I subscribe to this belief, mind you, but it is
worth pursuing.

Look at it this way : When women make up 51 % of the population, but 
only 10-12 % of the physics community  1) Why are there _any_
women in science, if it is so daunting (is it due, for example, to
mentors); 2) How can we achieve a more proportionate representation 
in physics; and 3) What would be the consequences to the field if we 
did have equity in physics (if women percieve things differently, will
this change the course of research).

  Like I said, I am dubious over claims of "differences in perception"
between the genders, but it is something I would like to hear more
discussion on, without snide Nazi or Communist references.  

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

         Dept of Physics                          
         Univ. of Texas                            
               at Arlington
From: matt@physics2.berkeley.edu (Matt Austern)
Newsgroups: sci.physics
Subject: Re: Truth vs beauty in physical theories
Date: 25 Jan 93 12:29:32
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
	<mcirvin.727989335@husc.harvard.edu>
Reply-To: matt@physics.berkeley.edu
NNTP-Posting-Host: physics2.berkeley.edu
In-reply-to: mcirvin@husc8.harvard.edu's message of 25 Jan 93 19:15:35 GMT

In article <mcirvin.727989335@husc.harvard.edu> mcirvin@husc8.harvard.edu (Matt McIrvin) writes:

> Of course, the picture is remarkably unified compared to what existed
> some decades ago; we're fairly certain that quantum field theory is at
> the root of it all, at least down to very small scales, and gauge
> interactions seem to be responsible for everything except (possibly)
> the Higgs. 

I would take out that "possibly".  That is: I don't know whether or
not a Higgs really exists (I'm skeptical), but whatever it is that
breaks SU(2)xU(1), I don't think it can be done by pure gauge
interactions.  Even if you believe in Technicolor, chiral symmetry
breaking isn't enough: you need something to give mass to the
technifermions, so you've only deferred to problem to a higher energy
scale.

--
Matthew Austern                   Just keep yelling until you attract a
(510) 644-2618                    crowd, then a constituency, a movement, a
austern@lbl.bitnet                faction, an army!  If you don't have any
matt@physics.berkeley.edu         solutions, become a part of the problem!
Newsgroups: sci.physics
From: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: PS precognitions of future physics
Organization: Whole Earth 'Lectronic Link
Date: Fri, 29 Jan 1993 02:25:46 GMT


I forgot a biggie. While at Tech Ops in 1962 I wrote a paper on coherence
(i.e. 2 point correlation) in thermal radiation published in Nuovo Cimento.
I got idea of quantum phase operator. I proposed this problem to Lenny
Susskind who was a grad student with me at Cornell in 63. I also got
Phil Morrison to let Johnny Glogower come to Cornell. Neither Glo or Lenny
had under grad degrees. Lenny, Glo and I spend considerable time working on
the problem together. Then I split for 6 months for the the sexy women in
Newport Beach working at Aeronutronic where I met Fred Cummings. I bought
a Jaguar convertible and did not have the money to pay tuition from my
Cornell assistantship. I was quite like Toady of Toad Hall. Anyway Lenny
Susskind published the famous paper in Physics 1964 on phase operators. It
is often quoted. He put Glogower's name on the paper but did not put mine.
I did not work on final form of paper so I can see why he did not put me
on as a co-author- but most definitely the proper thing to do would have
been to acknowledge my contribution at the beginning. I wasn't around and
I created a scandal at Cornell by not paying tuition- so Lenny made
a political decision of expediency. That's why he left my name out. He told
me years later at Yeshiva U that he may be remembered more for the phase
operator paper than for technicolor. Lenny has always played academic
politics very well. He is very smart.
Newsgroups: sci.physics
From: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: re:integrity
Organization: Whole Earth 'Lectronic Link
Date: Wed, 27 Jan 1993 04:56:32 GMT


From mcglk@cpac.washington.edu Tue Jan 26 18:46:41 1993
Date: Tue, 26 Jan 93 18:49:23 PST
From: Ken McGlothlen <mcglk@cpac.washington.edu>
To: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: Bass and Sawyer have disqualified themselves by flames.

You realize, of course, that you're a complete wacko.

Bass and Sawyer are both respectable scientific types who would strive to
enhance the signal-to-noise ratio of the group, and I applaud their efforts.
They've shown themselves to be more than qualified to handle the task at
hand.
It's obvious you're worried that your pseudoscientific claptrap is going to
have to move out of sci.physics---and quite honestly, I can't wait.  To have
*you* questioning their integrity is a real laugh.

Dear Ken,
Mind your manners.
Mad Dog Sarfatti
Wacky Jacky
From: christos@kuhub.cc.ukans.edu
Newsgroups: sci.physics
Subject: Solar Eclipse Question
Date: 21 Jan 93 23:02:36 CST
Organization: University of Kansas Academic Computing Services

Hello there,

	I have a question concerning the solar eclipse.
1. Is the moon rotating around the earth in a single plane sothat every 29 days
it comes in between the sun and the earth? If that is the case different places
of the earth should have solar eclipse every 29 days(period of the ratatioon of
the moon around the earth).

	I would appreciate any relevant response..

Feel free to send mail to 
Internet Address: RSL11@kuhub.cc.ukans.edu
Newsgroups: sci.physics
From: wksb16_csc@csc.cuhk.hk
Subject: Re: Home made monopoles
Organization: Computer Services Centre, C.U.H.K.
Date: Wed, 27 Jan 1993 02:16:31 GMT

In article <1jr3uiINNcjk@mirror.digex.com> bdoa@digex.digex.com (Barry Adams) writes:

>   

>                     Home made magnetic monopoles
>                     ============================

>   Contrary to popular belief , magnetic monopoles exist and are easy to
>make . Take a Steel hemisphere and cut a concentric hemisphere cut of the
>middle , now magnetize the hemisphere such that the domains of the object
>are aligned with the north (south) pole pointing outwards. Now stick two of
>the hemispheres together forming a sphere  (glue strong enough to resist
>the magnetic repulsion of the hemispheres is required) you now have your
>magnetic monopole :-) , since any observer will see the object having a north
>pole only (unless they cut it open).
>   Of course the configuration is unstable and the domains will slowly try
>to rearrange themselves to a more stable state. And the magnetic force still
>decays like a dipole. Such objects might to useful as frictionless bearings.

>Barry Adams

>   

	Have you really made such kind of "monopole"?  If so, have you made
some measurements on the magnetic field from this "monopole" ?  I don't think
you can really do these.

	There should not be any magnetic field outside your magnetic 
sphere.  The reason is obvious.  Divergence of magnetic is zero everywhere 
instrument is spherically symmetrical.  So, the magnetic field should be zero
outside the sphere.  You can understand the problem in another way.  Both
the north and south poles (one is on the inner surface and the other is on 
the outer surface) contributes equally to the magnetic field outside the 
your "monpole", just like the situation that there are equal quantity of +ve
and -ve charges distributed spherically symmetrically on the inner and outer
surface of a thick spherical shell.


							C.W.Kwok

Email Address: eddy-kwok@cuhk.hk	
Newsgroups: sci.physics
From: u108502@beta.lanl.gov (Andrew Poutiatine)
Subject: Re: Airplanes fly upside-down, how?
Organization: Los Alamos National Laboratory
Date: Thu, 28 Jan 1993 15:08:14 GMT

In article <1993Jan27.184332.1844@kth.se> myrberger@e.kth.se () writes:
>Hi,
>
>my question is simple this: How can an airplane fly upside-down?
>
>The normal explanation for how airplanes fly is (simplified perhaps):
>
>The wing is formed so the air have a longer way to go on the top, 
>therefore the air moves faster and an upward force is a fact.
>
>But when an airplane flies upside-down, a downward force should appear? Right?
>
>Johan

Your description of how lift is generated is one possible way of visualizing
it, but the flow geometry around the wing is influenced by many factors.
A couple of the more relevent ones here are angle of attack, and wing 
geometry.  The angle of attack is the angle at which the wing chord is 
positioned relative to the oncoming flow, i.e.:

            ------>   \ --
  air flow  ------>    \ ) angle of attack 
            ------>     \  
            ------>      \ wing
 
This picture of course shows an unusually large angle of attact, but you get the
picture.  The other factor I mentioned was the wing geometry, which is 
variable, by using the control surfaces, like flaps, slats, etc.

By varying the angle of attact and the wing geometry, one can vary the lift
on the wing, and in fact give negative lift, which of course is how aircraft
are able to execute steep dives.  These dives are in fact, depending on the 
aircraft, quite steep sometimes, like several g's in acceleration, which 
means that they are developing a lot of negative lift.

Turn your airplane upside down, and all you need to do is generate enough lift
for one g of acceleration to maintain level flight.

As far as your method of visualizing lift by thinking about flow lengths and
speeds, this still holds.  The geometry has been altered and the angel of 
attact is almost certainly negative so that the flow field is once again how
you have described it roughly, and a lift is generated to keep the plane 
aloft.

-AIP
 
Organization: Junior, Physics, Carnegie Mellon, Pittsburgh, PA