HDTenEightyP/NetNews huggingface dataset:
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: FTL Microwave Signal
Organization: University of Virginia
Date: Thu, 20 Aug 1992 19:41:02 GMT

In article <20AUG199213365493@elroy.uh.edu> elee969@elroy.uh.edu (Brown, William J.) writes:
>In the December 1991 issue of 'IEEE Microwave Guided Wave Letters', two
>researchers apparently claim to have measured a pulsed microwave signal in
>a waveguide that was travelling faster than light.  Has anybody heard anything
>about this? The reference is,
>
>G.C. Giakos and T.K. Ishii, "Rapid pulsed microwave propagation",
>IEEE Microwave Guided Wave Lett., vol. 1, pp. 374-375, Dec. 1991.
>
>
>
>William Brown
>Applied Electromagnetics Group
>Univ. of Houston


     This has come up several times here recently with no one seeming
     to express an opinion.  First, a further discussion of this
     can be found in three letters in IEEE Microwave and Guided Wave 
     Letters 2:199 (1992).  As I said a while back responses 1) and 3) are 
     a bit lame in that they are invalid if speeds > c actually exist.  
     Response 2) probably gets to the heart of matters, but is interestingly 
     uncompelling.

     As far as the results, they seem to imply that the leading edge of
     a certain non-TEM signal expands in a rather planar fashion
     (i.e. they go at the speed of light at objects on the centerline
     of the waveguide and at c/cos(theta) at angular
     deviations off of this line).  Thus as one approached pi/2 
     off of the waveguide centerline, the 'leading edge of the
     detected pulse' would approach infinite speed.

     To put it mildly, this seems hard to believe, but of course 
     stranger things have been known to occur and I can think
     of no *compelling* reason why their results are incorrect
     (though probably they are).

     To add to what I said earlier, I have received Giakos's dissertation
     from University Microfilms and can find no things that jump out
     as being patently wrong or misleading.  My guess is that the
     solution to this conundrum is in an assumption about the electronics,
     however, the solution is certainly not obvious to me and bears
     investigation.

                                   dale bass
-- 
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926
Xref: sparky sci.physics:12781 alt.religion.kibology:3455
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics,alt.religion.kibology
Subject: Re: Kibocolliders (was: Re: Super Conducting Supercollider)
Date: 13 Aug 92 18:32:42 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 <1992Aug13.030323.23331@nuscc.nus.sg>, matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes...
>Scott: well, for heaven's sake,man, spill the beans! How did Kibo
>explain himself? For my part, I doubt that this person is really Kibo.
>How can you be sure that he is not an impostor?

He told me I need a Fajita.  The sign at Taco Bell sayeth so.  

I suppose he is right.

-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: matt@physics.berkeley.edu (Matt Austern)
Newsgroups: sci.physics
Subject: Re: strong force
Date: 18 Aug 92 17:34:46
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
Reply-To: matt@physics.berkeley.edu
NNTP-Posting-Host: physics.berkeley.edu
In-reply-to: frisinv@alleg.edu's message of Tue, 18 Aug 1992 17:55:54 GMT

In article <1992Aug18.175554.18835@pellns.alleg.edu> frisinv@alleg.edu(Vincent Frisina) writes:

> Is there a mathematical force law for the strong force? If so, what is it?
> If there is no exact formula, what's the closest we have from what's  
> known? Thanks.

I'm afraid the answer is complicated.  It isn't just that we don't
have an "exact formula," but that the physical situation is
sufficiently messy that it wouldn't mean anything.

On one level, the "strong force" is the interaction between
hadrons---e.g., protons, neutrons, pi mesons.  These interactions are
very complicated, and can't just be reduced to a single function V(r).
The interaction between a proton and a pion is very different from
that betwen two neutrons; and even if you just pick some specific pair
of particles---a proton and a pion, say---it's more complicated than
just a situation of two particles attracting or repelling each other
as a function of distance.  The two particles can interact with each
other to form some other particle.  So, in this sense, the "strong
force" between hadrons is the totality of all experiments performed by
nuclear physicists and low-energy particle physicists.

On another level, the "strong force" is the interaction betwen two
quarks.  There, it makes a bit more sense to talk about some V(r).
However, we run into a different complication: at large distances r,
the strong force becomes so very strong that we never see free quarks.
So for large r, it isn't clear that it makes sense either to talk
about the force law, or, in fact, to talk about quarks at all.

For whatever it's worth, the best guess is that for short distances
the potential between two quarks looks like the Coulomb potential
(i.e., it goes as 1/r), and for long distances it is linear, i.e., it
goes as r.  There are a number of different models for interpolating
between these two asymptotic forms, all of which are rather similar in
practice. 



--
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
From: braham@physics.ubc.ca (Stephen Braham)
Subject: Re: black hole
Organization: University of British Columbia, Vancouver, B.C., Canada
Date: Mon, 17 Aug 1992 15:46:32 GMT

drabik@tech.ascom.ch (Pascal &) writes:
>   Can someone describe me how a black hole can evolve? I think it is
>created in a super nova, then it collects matter from other stars. It
>can melt by losing energy. Eventually, can it explode?

Yes, we expect nucleation to proceed from supernovae and the BH can then
collect matter. The evaporation will take a VERY long time though
for these (solar mass and above) holes, and thus you don't expect
them to reach the final stages in a time comparable to the age of our
universe. The holes that may be exploding now (or, rather, that
we could see exploding now) would be PRIMORDIAL holes, created from
instablity effects during the big bang itself. These little chappies
are so small that their lifetime is short enough. Whether or not
they'll be an explosion is an open question; some of us believe that
Hawking evaporation may be highly dependent on small scale physics,
and thus we can't be totally sure that it happens. If it DOES happen then
they'll probably be some form of explosion. In fact, we recently had a
meeting in which Stephen Hawking suggested that the final stage ends
in a`thunderbolt' singularity, which destroys the universe. It's
probable that there's someway out of it, as some BHs SHOULD have
gone off by now <grin>.

>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Dr. Pascal DRABIK            Tel:     +41 31-999-32-22        % You'll never %
>Ascom Tech Ltd.              Telefax: +41 31-999-36-07        %  know until  %
>Freiburgstrasse, 370                                          %  you try...  %
>CH-3018 Berne                e-mail : drabik@tech.ascom.ch    % ~~~~~~~~~~~~ %
>Switzerland                                                   % ~  ~~~~~~  ~ %

Ahhh, Freiburgstrasse! I know the Ascom offices :). I used to work at the
Universtaet Bern ITP :).

				Steve

--
| Name: Stephen P. Braham | Perversion: Quantum Cosmologist|
| Hangout: UBC physics    | Signature:  Euclidean          |
|          Vancouver, BC  |--------------------------------+
|          Canada         | E-mail: braham@physics.ubc.ca  |
Newsgroups: sci.physics
From: phfrom@nyx.uni-konstanz.de (Hartmut Frommert)
Subject: SU(5) GUT (was Re: Superbashing ...)
Organization: Dept. of Physics, University of Constance
Date: Fri, 14 Aug 1992 12:43:29 GMT

dwr2560@zeus.tamu.edu (RING, DAVID WAYNE) writes:

>phfrom@nyx.uni-konstanz.de (Hartmut Frommert) writes...
>>The coupling constants are also related in the SU(5) and other GUT's without
>>a new concept like SS

>This is news to me. Can you provide some more info on what non-SUSY SU(5)
>model is still consistent with the data?

This are two points:
1. The coupling constants, namely $g_3$, $g_2$, and $g_1$, corresponding to 
   the factor groups SU(3), SU(2), and U(1) of the rest symmetry group after
   the high energy SSB
          SU(5) --> SU(3)_{color} x [SU(2) x U(1)]_{GSW}
   (and before the GSW SSB)
   are correlated because they result from *ONE* gauge coupling constant
   $g_5$ by (non-elementary) renormalization calculus, see e.g. the 
   corresponding chapter in Becher, Boehm, Joos [1], or Paul Langacker's
   rather comprehensive review [2].

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
   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) ?

Some of the difficulties in SU(5) theory are absent with other GUTs, i.e. 
SO(10), etc..

Side remark: My impression is that a good figuring out of the SU(5) theory
  was never published (or did I really miss it ?). Everybody seemed to be 
  happy to have found the representations of fermions [and those are 
  hardly given in a manifestly consistent manner, try to add the spinor 
  indices] and Higgs bosons, and then concentrated on the most spectacular
  effect of the theory, i.e. proton decay.

References:
[1] Becher, Boehm, Joos: Eichtheorien. 2nd German Edition. 
    B.G. Teubner Verlag Stuttgart (Germany) 1983.
    An English translation [BBJ: Gauge Theories] was published by 
    Springer Verlag.
[2] Paul Langacker: Grand Unified Theories and Proton Decay. 
    Physics Reports 72, No. 4 (1981) 185--385.

--
 Hartmut Frommert, Physics, Univ of Constance, | + Whale killing is murder. +
 P.O.Box 55 60, D-W-7750 Konstanz, Germany | + Eat whale killers, not whales.
 E-Mail: <phfrom@dknkurz1.bitnet> or <phfrom@nyx.uni-konstanz.de>
+    "Windows NoT" expands in German to "Windows Noch Teurer"
+                                                ^even   ^more expensive
Newsgroups: sci.physics
From: jkwatson@amhux1.amherst.edu (John K. Watson '92)
Subject: Re: Order-of-Magnitude problems
Organization: Amherst College, Amherst MA
X-Newsreader: Tin 1.1 PL5
Date: Mon, 17 Aug 1992 16:22:16 GMT

Rob Salgado (sal7@ellis.uchicago.edu) wrote:
:         In trying to improve my physical intuition, I've been doing lots
: of Order-Of-Magnitude (Back-Of-The-Envelope) problems.  
: ...but I'm stumped by the following:
:  
:         Use the uncertainty principle to compute how long an ordinary
:         lead pencil can be balanced upside down on its point.
:                                                 [QM: Das/Melissinos p. 53]
: Any ideas?
:  
:  
Well, if I remember correctly, my father, a physicist at Kent State, gave
a problem similar to this on one of his senior level finals.  His problem 
involved bouncing a ping-pong ball on top of another, larger ball.  Given
completely elastic collisions, and the radii of the two balls, estimate how
many times the ping pong ball can bounce on top of the other ball before it
falls off, using the uncertainty principle.  The solution of the problem 
involved the uncertainty in the place which the ping pong ball bounced on the
other ball.  As time progresses, the area over which the ball will be able 
to hit increases, until finally, it will be far enough out that it will not
bounce on the bigger ball any more.  I imagine the pencil problem would be a 
matter of the uncertainty in the position and momentum of the top of the 
pencil, which will eventually get big enough for the center of mass to move
so it was not over the support any more.  
		Hope this helps...
			John
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Symmetries, groups, and categories
Date: 20 Aug 92 20:55:40 GMT
Article-I.D.: husc8.mcirvin.714344140
 <1992Aug17.184957.18492@galois.mit.edu> <1188@kepler1.rentec.com>
Distribution: na

andrew@rentec.com (Andrew Mullhaupt) writes:

>Hey while we're hammering physics for ill-chosen terminology, can we at least
>change it to 'renormalization monoid'?

And "pseudometric tensor" in relativity.

My algebra's rusty.  What's the difference between a monoid and a
semigroup?  Some textbooks say that it's really a renormalization
semigroup.  They give the nature of the composition law as evidence.
"Monoid" is more general, right?

What I find strange is that the term is used even though the
[monoid/group/semigroup] nature of the beast isn't particularly
illuminating or important.  The term seems to be the result of
enthusiasm for group theory bleeding into places where it has
little relevance.

-- 
Matt McIrvin, Cambridge, Massachusetts, USA
From: fhide@srcwsc.src.sony.co.jp (Fumitomo HIDE)
Newsgroups: sci.physics
Subject: names of physics books
Date: 21 Aug 92 03:34:10 GMT
Organization: Sony Corporation, Research Center, Yokohama, Japan.

Does anybody know about the elementary physics texts written by
Purcell and Marion? I know the one by Purcell is about E&M. 

If anybody knows the full names of the authors, the titles, publisher, etc,
please mail me directly with the information. Thanks.

-----
	Fumitomo HIDE     e-mail: fhide@src.sony.co.jp
	Sony Corporation Research Center
	174, Fujitsuka-cho, Hodogaya-ku, Yokohama, 240 Japan.
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Newsgroups: sci.physics
Subject: Re: Hubble constant?
Date: 13 Aug 92 00:52:00 GMT
Organization: Texas A&M University, Academic Computing Services
News-Software: VAX/VMS VNEWS 1.41

scip1061@nuscc.nus.sg (Marc Paul Jozef) writes...
>  In reaction to my suggestion that, if anything, Newton predicts
>a universe that expands with constant rate, Ted and Dave Ring
>replied by saying that Newton did not necessarily make sense in
>this situation. I agree. So we all seem to agree that 

I think I said that a careful Newtonian argument shows, correctly, that
the expansion slows down.

>`slow-down of expansion-rate due to mutual attraction' is falsely
>appealing to Newtonian intuition.

>My second point was that Einstein's theory predicts a universe
>with constant expansion-rate if one `discretesizes' the
>stress-energy tensor.

>Dave Ring says that this is false because the global behaviour
>of the universe is stable with respect to density-fluctuations.
>I guess you are talking here about density-fluctuations of the
>`perfect fluid'. What I had in mind was the following.

Doesn't matter. So long as the fluctuations are smaller than the radius of
the universe.

>Idealize all matter to be concentrated in various discrete
>points of the Friedmann spatial universe. Subsequently, regard
>the stress-energy tensor as being zero outside the worlcurves
>of these discrete matter-occupied points (and being something
>irrelevant on the worldcurves). Thus the stress-energy tensor
>is a `delta-tensor' d.

I seem to remember this being treated in MTW but I can't find it. The
conclusion was as I stated before, that on large enough scales you can
consider the stuff homogeneous.

>It is a straightforward exercise to check that Einstein's equation
>G(g) = d (where g is a Friedmann-metric) has as solutions only
>a static euclidean universe, or a hyperbolic universe that is 
>either shrinking or expanding with constant rate.

I don't believe it. Show us.

The rest of the post seems right.

Dave Ring
dwr2560@zeus.tamu.edu
Xref: sparky sci.physics:12754 alt.religion.kibology:3440
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Newsgroups: sci.physics,alt.religion.kibology
Subject: Re: Kibocolliders (was: Re: Super Conducting Supercollider)
Date: 13 Aug 92 03:03:23 GMT
Distribution: na
Organization: National University of Singapore

Scott: well, for heaven's sake,man, spill the beans! How did Kibo
explain himself? For my part, I doubt that this person is really Kibo.
How can you be sure that he is not an impostor?
From: hinson@maxwell.physics.purdue.edu (Jason W. Hinson)
Newsgroups: sci.physics
Subject: A "preferred reference frame"
Date: 15 Aug 92 02:48:31 GMT
Organization: Purdue University Physics Department

The following is a science fictional excursion discussing the possiblity
of space-time having a preferred frame of reference without violating
relativity.  My request is that someone tell me how we know that it cannot
be true.

Perhaps space-time is something like what was beleived to be the ether.
However, this medium of wave propagation would have the strange property
that an electromagnetic wave moving through it would be seen by all 
inertial observers as having a speed c. This would take into account
at least the effects of special relativity.

If the above were not an impossiblity, then space time could have a 
particular fram of reference.  Then one could fictionally warp that
space time to send a message/traveler to another point in space faster
than light could reach that point.  Then, the message/traveler would
have the time/space line of the preferred reference frame no matter who
is observing the message/traveler. So there would be no problem with
causality violations (I bleive).

That last comment promps another question:  Is it true (as I think it
is) that if there were some prefered reference frame, then we could
travel from A to B faster than light without violating causality?
For example, assume we can send messages faster than light; however
everyone (and everything) agrees not to send or recieve such messages
unless he/she/it is stationary relative to.. say... the Earth.
Could there still be a violation of causality?
(to make it easier, assume that we could send the message instantaniously;
however, since no one would send or recieve the messages unless he is
not moving relative to the earth, instantaniously would, in effect, always
mean "in the reference frame of Earth.")

Thanks for any input
-Jay
Newsgroups: sci.physics
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: The dangers in microwaved food...
Organization: University of Virginia
Date: Fri, 21 Aug 1992 04:15:50 GMT

In article <1992Aug20.190055.8807@ll.mit.edu> ryba@ll.mit.edu (Marty Ryba) writes:
>
>In article <10200@vice.ICO.TEK.COM>, hall@vice.ICO.TEK.COM (Harold F Lillywhite) writes:
>|> Or eggs.  Unless the membrane is pierced they can build up a lot of
>|> internal pressure.  The same probably applies to any food with a
>|> reasonably impervious layer on the outside.  The quick heating of a
>|> microwave oven can turn it into a potential bomb which can explode 
>|> when some poor soul cuts it or pokes it with a fork.
>
>   This reminds me of a scary/funny-but-true story --
>
>My college roommate was a wealthy Indian who, like most Indian men of his
>social class, knew absolutely nothing about cooking.  He proceeded to
>microwave an egg.  When he removed it from the oven, it was too hot, so
>he dipped it in a glass of water.  BOOM!!  There was egg *everywhere*,
>including the ceiling!  Fortunately, he was wearing his contact lenses,
>because a bit of eggshell found his eye and destroyed the contact lens.
>He would have suffered major cornea damage otherwise.
>

     I've got to try the water thing.  Thanks for the help with this
     important experiment.

                               dale bass
-- 
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926
Newsgroups: sci.physics
From: rdc@pelican.cit.cornell.edu (Bob Cowles)
Subject: Re: BLACKHOLES IN THE CENTRE OF THE EARTH
Date: Wed, 19 Aug 1992 17:21:29 GMT
Organization: Cornell Info. Tech.


Is there any "back-of-the-envelope" calculation that has been done to
size a black hole of "nuclear" density? (whatever that means) ...along
the lines of "if the nucleii of x uranium (or take your pick) atoms
were "combined" to the same average density as a single nucleus, then the
mass is sufficient to form a black hole"?  Any idea what the number would be?

Bob Cowles
rdc1@cornell.edu
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: Order-of-Magnitude problems
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Tue, 18 Aug 1992 05:26:00 GMT

>Rob Salgado (sal7@ellis.uchicago.edu) wrote:
>:         In trying to improve my physical intuition, I've been doing lots
>: of Order-Of-Magnitude (Back-Of-The-Envelope) problems.  
>: ...but I'm stumped by the following:
>:  
>:         Use the uncertainty principle to compute how long an ordinary
>:         lead pencil can be balanced upside down on its point.

Well, since we only want OOM...

If you assume the pencil falls from vertical with no impulse, its motion
is given by theta = theta_0 exp[sqrt(3g/2l)t] for small theta. The
question is, for what t is this of order 1 , i.e. what is th_0 . At t=0
there is a characteristic angular velocity w_0 = th_0 * sqrt(3g/2l) . We
will use the uncertainty relation

hbar = th_0 * L = th_0 * l^2*m/3 * sqrt(3g/2l)

thus (th_0)^4 = 6*hbar^2/(m^2*l^3*g)

If we sqeezed th_0 any more then we would get a faster time because the 
velocity would quickly put the pencil farther out than th_0 .

(th=1) occurs around  t = sqrt(l/24g)ln(m^2*l^3*g/6hbar^2) ~ 3s for a pencil.

This calculation is for T=0. At room temperature the thermal motion will
be more important than the uncertainty relation, but because of
the logarithm the answer won't change much.

Dave Ring
dwr2560@zeus.tamu.edu
From: Eric_S_Klien@cup.portal.com
Newsgroups: sci.physics
Subject: Re: Nevada Casino - 200 miles up
Date: Tue, 18 Aug 92 19:44:00 PDT
Organization: The Portal System (TM)
Distribution: world

"   Could you be more exact as to what 2026 AD technology is?"
 
I'm thinking nuclear fusion for propulsion on the casino and some
advanced substance for the tethers.
 
"I'd recommend trying to figure out the thrust you'd need.  I think it
could be a fun problem."
 
I'm unable to do this.  Can anyone help?  I'd be interested in the 
thrust requirements for different attitudes, perhaps 200 miles, 2000 
miles, 20000 miles, and 23,000 miles.  
 
                                                           Eric Klien