HDTenEightyP/NetNews huggingface dataset:
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: "What's New" July-24-1992
Organization: University of Virginia
Date: Wed, 29 Jul 1992 01:00:55 GMT

In article <1992Jul29.001551.3229@murdoch.acc.Virginia.EDU> gsh7w@fermi.clas.Virginia.EDU (Greg Hennessy) writes:
>In article <1992Jul28.235639.2933@murdoch.acc.Virginia.EDU>
>crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes: 
>#     P.S. I don't see APS officers testifying before Congress about
>#     chiropractors or astrology
>
>Gee, Dale, I was unaware that taxpayer dollars were being spent on
>chiropractors or astrology. How much money is being budgeted on these
>activities? 

    NIH is being forced to fund study into chiropractry(?) along with the
    other 'alternative medicine' approaches. 

    As far as astrology goes, I'd think that such widespread antiscientific
    beliefs would be of great interest to those in the APS apparently
    interested in scientific purity.  
 
    Also, I'm sure such base things as dollars never come into consideration
    of certain members of the APS when things like the integrity of science
    come into play.  After all, we have been told many times that the APS
    is not against SSF because of the competition for money, just because
    'it is not science'. 

                                  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: ldd@src.umd.edu (Lee Davisson)
Subject: Re: how do you do the one about an infinite mesh of 1ohm resistors ...
Organization: Systems Research Center, Maryversity of Uniland, College Park
Date: Wed, 29 Jul 1992 06:46:52 GMT

A. Zemanian has recently written several papers and a book about infinite
networks; the generalizations of this problem show that the "superposition
trick" answer fudges some important issues about infinite objects, even
though it gives the right answer.

David

Newsgroups: sci.physics
From: metares@well.sf.ca.us (Tom Van Flandern)
Subject: Twins Paradox Resolved
Organization: Whole Earth 'Lectronic Link
Date: Wed, 22 Jul 1992 05:41:37 GMT


     After 25 messages in three days on the Twins Paradox, the silence over
the past few days has been deafening.  In the earlier example, there was no
mathematical paradox, but there was a logical paradox.  To review:

     Consider an inertial frame containing the Earth and Alpha Centauri (AC),
four light years apart and having clocks synchronized within their own frame.
And consider another inertial frame containing another two planets, T1 and
T2, also four light years apart and synchronized within their own frame.  Let
the two frames have a relative velocity of 99% of the speed of light.  [This
implies a time dilation and distance contraction of a factor of about seven.]

     Assume that one day T1 and the Earth encounter one another.  Babies are
born simultaneously on both planets as they pass, with T1 headed in the
direction of AC and T2 still headed toward Earth.

     Eventually, T1 passes close by AC, and they compare notes.  How old will
the T1 child be when this happens?

     How old will the Earth child be when Earth passes T2?

     A) 4 years old
     B) 7 months old
     C) other (explain)

     The significance of this version is its perfect symmetry, and the total
absence of accelerations, turn-arounds, or frame changes, either during the
journey or at any time in the past or future.

     Now here is the resolution:

     There are four events:
     T1 meets E1: both are age zero.
     T1 meets E2: T1 age 7 months, E2 age 4 years.
     T2 meets E1: T2 age 4 years, E1 age 7 months.
     T2 meets E2: both are age 4 years plus 7 months.

     For those unfamiliar with SR, SR implies that events synchronized in one
frame will not be synchronized (= simultaneous) in a relatively moving frame.

     So the situation for the twins IS perfectly symmetric for both frames,
as the math requires.  Understanding this is the principal key to resolving
the logical paradox, and for understanding SR.  The key reason that the twins
can be perfectly symmetric, yet show different aging, is this:  In any frame,
the apparent rate of progress of time (and distance) for a fast-moving
traveler is quite different when the traveler is moving away, from what it is
for an approaching traveler.  Naturally, neither the E-frame nor the T-frame
runs systematically slower or faster than the other, since they are
equivalent.

     If we can agree on the resolution of the paradox, then perhaps we can go
on to discuss its significance.  This version of the paradox reveals one or
two loopholes in the usual understanding of special relativity with
interesting implications for physics.  -|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: johncobb@ut-emx.cc.utexas.edu (John W. Cobb)
Newsgroups: sci.physics
Subject: Re: Propulsion questions
Date: 23 Jul 92 18:10:44 GMT
Reply-To: johncobb@ut-emx.cc.utexas.edu (John W. Cobb)
Organization: The University of Texas at Austin

In article <HAGERMAN.92Jul20182314@rx7.ece.cmu.edu>,
hagerman@ece.cmu.edu (John Hagerman) writes:
|>In article <76248@ut-emx.uucp> johncobb@ut-emx.cc.utexas.edu (John W.
Cobb) writes:
|>>
|>> Now for fusion you've got to go even
|>> further. Imagine trying to load a TOKAMAK into a spaceship. It's mass
|>> is huge {...}

|>How about using inertial confinement?  What are the heavy components?
|>
Capacitor banks. Look at some of the big Laser systems. They aren't light.
I'm out of my league here (but not as far out as my comments on solar
sailing --- how embarrasing) so maybe people have addressed these issues.
Moreover, the focussing has to be very precise or you don't get ignition.
Imagine trying to damp-out mechanical vibrations on a space ship over
the integrate light path over all optical elements. One usual way is to
add mass and dampers. Well you don't want to just add mass willy-nilly
for a spaceship.

There is another idea that uses lasers. I believe it came out of Livermore
a decade or so ago. The idea is to use ground based lasers. Focus them on
an ablative underbelly of a space-craft and use the thrust generated for
manuevering and perhaps even orbit lifting. The beauty is that your
power source never has to be launched. The difficulty is that you have to
track your craft, focus your beam, and penetrate the atmosphere. The fact 
that you would even consider such a scheme indicates how important it is
to decrease powerplant mass on these high specific impulse systems.

john w. cobb
jwc@fusion.ph.utexas.edu
From: mcirvin@husc10.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Small clarifications for my big article on four-vectors
Summary: Just some tweaking...
Keywords: four-vectors
Date: 22 Jul 92 02:29:00 GMT
Article-I.D.: husc3.1992Jul21.222902.14036
Distribution: world
Organization: Harvard University Science Center

In my big article on relativity and four-vectors, I wrote:

>We then have a very nice-looking
>relation between four-vectors

>       P = mV ,

>where P is the four-momentum, V is the four-velocity, and
                ^^^^^^^^^^^^^
>m is the invariant, unchanging mass. 

Just to be clear: this "four-momentum" P is the same thing as the
"energy-momentum four-vector" P mentioned earlier.

>Four-acceleration A is the derivative of four-velocity with
>respect to time. 
            ^^^^ 
That's *proper* time, not the t coordinate.

I hope you enjoyed the article... boy, am I wasting a lot of time
these days.

-- 
Matt McIrvin   mcirvin@husc.harvard.edu   Long live short .sigs
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Defining Photons
Keywords: Relating photons E=MC^2 criticism
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Mon, 27 Jul 92 22:40:40 GMT

NOTE: John C. Baez is the author of this article.  I am only using my
account to post this article for John as a favor - Mark Corscadden

In article <3942@cruzio.santa-cruz.ca.us> snarfy@cruzio.santa-cruz.ca.us writes:

>
>       If you are a college professor , the taxpayers  or  students  pay
>       you to enlighten and clarify issues pertaining to your specialty.
>       Why then have you not yet found a word other than ``particle'' to
>       describe  that  which has no mass , to differentiate it from that
>       which does?.  I think it's because some of you  would  prefer  to
>       confuse people rather than teach them. The photon, as a concept ,
>       would  be  more accurately described as a ``phenomena'' given the
>       difficulty  you  have  manipulating  it  the  same   way   as   a
>       ``particle''   mathematically.  (multiplying  by  zero  ,for  one
>       thing).
>
>      I find it odd that you have a job.


Ouch.  Us college professors have an incredibly useful term which
applies to photons and distinguishes them from particles which have
mass.  "Massless particle."  I agree that massless particles must be
treated differently in many respects from massive ones.  For example, if
photons were massive one would expect them to have three spin states, 1,
0, and -1, but being massless they only have two, 1 and -1.  More to the
point of the present discussion, massless particles in quantum field
theory do not admit position operators with the same properties as
massive particles.  (People write hundreds of papers on this -- try
looking under "Newton-Wigner localization".  Basically the problem is
that the usual definition of particle position operators in quantum
field theory (which by the way they never teach one in a QFT course),
when applied to massless particles, would result in division by zero.)

Nontheless, the physical similarities between massive and massless
particles, and the mathematical similarities in their descriptions, are
so great that people have decided to call them both "particles".  Since
even massive particles have wavelike properties it's really not so odd.
Frankly, they should both be called "wavicles", but most people find
that neologism too cutesy.  

I doubt that making up another term for massless particles would make
quantum field theory accessible to the masses (sorry for the pun), and
it's really only in quantum field theory that all this particle/wave
stuff gets cleared up.  Of course you are welcome to make up a new term
and see if it catches on.  

John Baez
From: jstravis@bass.bu.edu (John Travis)
Newsgroups: sci.physics
Subject: Physics postdocs respond!
Date: 28 Jul 92 12:24:21 GMT
Reply-To: jstravis@bass.bu.edu (John Travis)
Followup-To: sci.physics
Organization: Boston University


Hi everyone. Here'a an opportunity for postdocs to get all their
gripes off their chests. I'm a writer for Science magazine and
for our upcoming special issues on Careers in Science I'm writing
an article broadly titled "The Lot of a Postdoc" So tell me what's good
and bad about being a POSTDOC IN 1992.  Some of the obvious issues I'm looking
for input on are:
Preparation for future teaching, if any
Money woes
Foreign Postdocs--do you look for the same benefits out of your experience
US Postdocs in Europe
Multiple Postdocs!!!
Postdoc while trying to raise/support a family
Postdocs in industry
Postdocs in small schools, big schools, small and big labs

Innundate me with email, a call or a fax and perhaps we'' talk in depth
about youtr situation in particular.

work 617-288-7939
fax   617-288-7768

Thanks for helping me get a good snapshot of postdoc life.

John Travis
Science (Northeast Bureau)
From: snarfy@cruzio.santa-cruz.ca.us
Newsgroups: sci.physics
Subject: QPKD and Quantum Communications
Keywords: Communications Public Snide Remarks
Date: Mon, 20 Jul 92 18:29:15 PDT
Reply-To: snarfy@cruzio.santa-cruz.ca.us



In article <3919@cruzio.santa-cruz.ca.us>, snarfy@cruzio writes:
> >  Mr Weiner says:
> >  > This has nothing to do with FTL anything.

> >  Dogmatic  sort  aren't  you ?  Instantaneous is by definition faster than
> >  light.

> Look, bozo, if you're going to quote private e-mail, get it right...


       Do you consider the sci.physics forum to be your Private E-Mail?

                        >....starting with my name.

       A thousand pardons ,Dick , I mean Frank , I mean Mr. Wiener, There
       hows that?


> > My "this" was in reference to EPR as a means
> > of communication,....

    Thank you for clarifying that.

> >             .....which is not instantanous communication, unless, of
> > course, you start defining words as you go along.

       I  saw EPR mentioned nowhere in this discussion until you brought
       it up. That makes you responsible  for  defining  the  term  (and
       properly   assigning   pronouns)   .    Before   we   allow  this
       conversation to deteriorate further  ,  what's  REALLY  bothering
       you?  No  kidding  , I'm  interested  -  Snarfy  (if  you  prefer
       ``Bozo'', fine ,but no points for originality.)


Newsgroups: sci.physics
From: franl@centerline.com (Fran Litterio)
Subject: Re: Defining Photons
Organization: CenterLine Software, Inc.
Date: Tue, 28 Jul 1992 22:34:19 GMT

snarfy@cruzio.santa-cruz.ca.us writes:

> ``I'M JUST TRYING TO POINT OUT THAT OHM'S LAW DOESN'T  INCLUDE  A
> TIME   OR   DISTANCE   FACTOR''  Screams  Snarfy.``  That  allows
> communication of information about changes  the  rate  of  energy
> transfer  back  to  the  E  transmitter from the E receiver to be
> instantaneous once a connection is made, by means of lowering the
> impedance of the receiving object! ''

I'm not an expert on the subject, but I could swear that I've heard
that Ohm's Law was never an exact description of reality in the first
place (even before QM and relativity).  If so, the obvious question
is: Does whatever passes for the modern replacement for Ohm's Law (if
such exists) also lack a time parameter?
--
franl@centerline.com   || Fran Litterio                               
uunet!centerline!franl || CenterLine Software R&D                     
617-498-3255           || 10 Fawcett St, Cambridge, MA, USA 02138-1110
From: jmp1@ns1.cc.lehigh.edu (JEFFREY MICHAEL PARSONS)
Newsgroups: sci.physics
Subject: Re: Space Station & APS
Date: 30 Jul 92 21:43:39 GMT
Organization: Lehigh University

Can anyone confirm what Sen. Grahm (Texas) said on CBS This Morning (7/30/92)?
I believe that he said that governmental funding of science research has gone
from a former (stable) 5% of the budget to 1.8% (1.6% without the SSC) under
the current Congress.  He noted that this trend appears to be continuing.  I
would also add that it is my impression that a smaller percentage of federal
science funding is going to physics.  Does anyone have a source which confirms
or refutes these facts?  Dale, what does your crystal ball have to say? :-)

Jeff Parsons
Lehigh University
Physics Undergrad
--
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Newsgroups: sci.physics
Subject: Re: Aristotle and the Modern Physicist
Date: 24 Jul 92 02:46:19 GMT
Organization: National University of Singapore

"you can't deny that the metric affects where they end up going..."
I realise that I may have been a little unfair to SOME modern
physicists. I am aware, too, that not everybody takes the "exchange of
virtual particles" bit very seriously. But I do claim that many people
think of gravitation as an "interaction". Which it is NOT; this being
the main point of GR. Now without getting too philosophical about it, I
suppose that when people say that two things "interact", they mean that
these things end up doing something that they otherwise would not. I am
pretty sure that, though they may protest otherwise, a lot of people
privately think of gravitation as just another "interaction", albeit one
with an unusually complicated classical version. But this is simply
wrong: as Aristotle said, the Earth goes around the Sun on an
approxiamtely elliptical orbit NOT because it is being "forced" to do
so, NOT because it is"interacting" with the Sun, but rather because it
is NOT interacting with the Sun. To ask, "why does the Earth go around
the Sun?" is precisely analogous to asking Newton or Galileo why a free
particle moves in a straight line at constant speed. What would you have
it do? I fear...correct me if I am mistaken... that when you say that
the "metric affects where they are going" you are thinking of the metric
tensor as a thing that lives on Minkowski space: the particle would
really like to follow the Minkowski geodesics, but the metric compels it
to go elsewhere. Would you say that the Minkowski metric "interacts"
with free particles in Minkowski space and "forces" them to move along
straight lines ["inertons"!]? No? Well, if you do not wish to say it of
Minkowski space, then don't say it of any other spacetime. "Gravity" was
all a mistake, resulting from our ignorance of spacetime curvature. How
does one quantize a mistake?
Newsgroups: sci.physics
From: hsk@microplex.com (Harjeet Kalsi)
Subject: What are those things called...
Organization: Microplex Systems Ltd.
Date: Thu, 23 Jul 1992 21:42:14 GMT

Sorry this article previously got posted in the wrong thread (hope it works
this time).  Here it is again.

I know I've seen them in physics labs (including mine when I was in school) 
but forgotten what this "box" with two antennas, that has a high
voltage spark travelling between the antennas from bottom to top,
is called.

Also, does anyone have any instructions on how to make one?

Please respond via e-mail or public forum if it's of general interest.
Many thanks in advance.



hsk@microplex.com
From: wolf@prosun.first.gmd.de (Wolfgang Koehler)
Newsgroups: sci.physics
Subject: Re:  Bell dethrowned, part II
Keywords: EPR, Bell, Aspect, Quantum mechanics
Date: 29 Jul 92 10:04:36 GMT
Organization: GMD-FIRST, D-1000 Berlin 10


I'm wondering why none of the sci.physics gurus gives any comments to
this surprising posting ?

To me - and probably to many other listeners - it would be very interesting
to hear the views of the net, since I'm not clever enough to see mistakes
in the computations.

Or have I missed them  among all this garbage about 'structure of time' ?


wolf

-- 
-------------------------------------------------------------------------------
    ... always look on the bright side of life ... (Monty Python)
-------------------------------------------------------------------------------
Wolfgang Koehler                                    wolf@first.gmd.de

GMD - FIRST an der TU Berlin                   German National Research Centre 
                                                    for Computer Science
Fachbereich 20

Sekretariat FR 2/1


From: alexa@hpnmdla.sr.hp.com (Alexander Anger)
Date: Fri, 24 Jul 1992 19:28:40 GMT
Subject: Re: What if there were 2 time and 2 space dimensions?
Organization: Hewlett-Packard, Santa Rosa, CA
Newsgroups: sci.physics

In sci.physics, jbaez@nevanlinna.mit.edu (John C. Baez) writes:

>   As far as I can tell, this just goes to show that there are a lot of
>   mathematicians pretending to be physicists, and/or lots of physicists
>   who feel the need to publish a lot, because I can't think of any good
>   PHYSICAL reason for redoing fancy physics like supersymmetric Yang-Mills
>   theories in a universe with 2 space and 2 time dimensions!  As a math
>   problem I suppose checking out how self-duality works in this signature
>   is rather fun if you like that sort of thing.  

I seem to have found a like-minded individual here!

Alex

Xref: sparky sci.physics:11905 sci.environment:10229 sci.energy:3766
From: charlesg@milton.u.washington.edu (Charles Grant)
Newsgroups: sci.physics,sci.environment,sci.energy
Subject: Re: Running out of oil.  Was Re: Is car pooling for real? (was Re: Are
Date: 29 Jul 92 02:53:27 GMT
Organization: University of Washington, Seattle

In article <1992Jul28.023431.16111@michael.apple.com> ems@michael.apple.com (E. Michael Smith) writes:

>So, yes, you are right that someday we will run out of cheap energy.
>But, no, it won't be in 100 years.  It will be in something on the 
>order of 5,000+ years (presuming no significant technological advance
>in that time frame).

You also tacitly assume no significant increase in energy consumption. If
the current human population is 5*10^9, and the doubling period for the
population is 50 years, then in 5000 years the population will be

	(5*10^9)*(2^100) ~ 10^40

If each person weighs about 50 kg, then the "mass of humanity" in 5000 years
is going to be around 10^41 kg. Note that the mass of the earth is only about
10^25 kg.

Obviously something is going to happen to increase the length of
the doubling period, but until we figure out what that is, I can't
put much stock in 5000 year estimates of the earth's resources.

Charles Grant
Organization: Penn State University
Date: Wed, 22 Jul 1992 11:12:41 EDT
From: <MRG3@psuvm.psu.edu>
Newsgroups: sci.physics
Subject: Re: Quantum Cosmological Boundaries and Determinisim?


A quick comment on the role of the wavefunction/density matrix
in consistent histories (ala Hartle & Gell-Mann):
There is an initial condition (i.e. initial density operator) to be specified
in the decoherence functional.  The initial conditions will  determine in part
which histories decohere, and are quasi-classical.  The specific dynamics, and
choice of coarse graining will also be important.


A variation of this scheme included two density operators for both initial and
final conditions. This seemed to be an attempt to remove the apparent
introduction of time asymetry by hand. I hope the proposal has died a quiet and
painless death. :)

-mike gallis
mrg3@psuvm.psu.edu
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Blue Sky
Date: 27 Jul 92 18:46:15 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

Jeff Love writes:
>Ok, so Rayleigh scattering explains why the sky is blue: blue light is
>scattered more than red light. I guess I don't like this explanation since
>I don't know why  Rayleigh scattering preferentially scatters blue light.
>Is their a **classical** (i.e. no QM) explanation for this effect? If DaVinci
>got it right as Jackson claims in his book, then there must be a classical
>arguement.

Have you actually tried reading Jackson's explanation?  As a hint,
Jackson's title is _Classical Electrodynamics_.  More to the point,
if _Rayleigh_ got it right in 1871 there must indeed be a classical
explanation, namely Rayleigh's.  [Rayleigh, Phil Mag XLI, 107, 274,
(1871), and Phil Mag XLVII, 375 (1899), refs cribbed from Jackson]
Basically the assumptions that go into the explanation are that
molecules have predominantly electric dipole polarizability, and 
that they are small compared to the wavelength of the light.
Incidentally, I believe that da Vinci understood that blue light
was scattered preferentially, causing the blue sky, but didn't know
why.  (He certainly didn't derive a k^4 dependence).  I don't think
one can claim that his argument is based on "classical physics" in
the usual sense.

BTW, to Al Kriman: Perhaps if prophecies of the decline of atmospheric
ozone are true, we will eventually see a more violet sky.

Ben Weiner

I don't think of myself as a classical physicist, rather a
twelve-tone physicist.