HDTenEightyP/NetNews huggingface dataset:
From: hsk@microplex.com (Harjeet Kalsi)
Subject: What are those things called...
Organization: Microplex Systems Ltd.
Date: Thu, 23 Jul 1992 20:53:00 GMT


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
Newsgroups: sci.physics
From: jmc@SAIL.Stanford.EDU (John McCarthy)
Subject: Re: scientific literature
Reply-To: jmc@cs.Stanford.EDU
Organization: Computer Science Department, Stanford University
Distribution: na
Date: 26 Jul 92 14:25:59

The critical criterion for a scientific journal these days is whether
the articles are subjected to peer review as a criterion for being
published.  _Scientific American_ doesn't do this, and the articles
in the _News and Comment_ section of _Science_ aren't either.  Neither
are the articles in _Technology Review_ or the articles in the
National Academies' _Issues in Science and Technology_.  My opinion
is that there should be a refereed magazine dealing in popular
language with issues arising out of science and technology.  The
refereeing might have a different character than standard scientific
refereeing.  The referees couldn't reject an article on the grounds
that the author was wrong, but they could make him deal with a
consideration he was ignoring.
--
John McCarthy, Computer Science Department, Stanford, CA 94305
*
He who refuses to do arithmetic is doomed to talk nonsense.
From: imw@siesoft.co.uk (Ian Wild)
Newsgroups: sci.physics
Subject: Re: The unseen photon (riddle of existence)
Date: 24 Jul 92 16:43:44 GMT
Organization: Siemens Nixdorf Information Systems Ltd.
X-Newsreader: Tin 1.1 PL4

tolman%asylum.cs.utah.edu@cs.utah.edu (Kenneth Tolman) writes:
: 
:   Let us suppose that we fired a photon towards our two slit experiment-
: yet we set up no screen to absorb it.  In fact, the poor photon keeps
: on going, and is not absorbed by anything.  It travels out into outer
: space, and keeps on going.
:
: ...
: 
:   But does that photon exist, or not, if it never interacts again?

Who cares?

Seriously.  If it never has any interactions again, how can anyone (or
anything) be affected by its existence (or lack thereof)?

BTW - why did you need the two slits up front?  If I fire off a photon
from my pocket laser, carefully aiming so that it misses everything in
the whole universe, does *that* photon exist?  And how would you prove
it?

imw
From: sichase@csa3.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Defining Photons
Date: 27 Jul 92 17:51:45 GMT
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: na
Reply-To: sichase@csa3.lbl.gov
NNTP-Posting-Host: 128.3.254.198
Keywords: Relating photons E=MC^2 criticism
News-Software: VAX/VMS VNEWS 1.3-4   

In article <1992Jul27.033211.26912@Princeton.EDU>, vgurarie@phoenix.Princeton.EDU (Victor V. Gurarie) writes...
> 
>   I have a strong feeling that one would NEVER be able to produce a
>semiclassical state of W or Z particles. They are so massive that they
>would decay BEFORE we could form a semiclassical state. Also their
>characteristic length is R=1/M, M - mass. 

Whether we have the technology to do so or not is rather beside the point.
In principle it *is* possible to produce enough of them in short enough 
a period of time to produce such a state.  It just seems unlikely that anyone
will apply for NSF funding to do so in the near future.

And the "characteristic length" is not applicable here at all because we
are talking about physical (on shell) W's.  The relevant quantity is 
width, not mass (which is about 2.2 GeV instead of ~80 GeV - still a short
lived system).

> It is masslessness of the photon
>which makes it behave like a wave. (and its stability). Anyway, 

Once again, this is completely false.  Rather than repeat what I and several
others have already explained, I suggest that any interested persons find
J.J. Sakuri's Advanced Quantum Mechanics and study up a little on the 
semiclassical limits of quantum fields.  (I am pretty sure Sakuri discusses
the subject.  If not, try Bjorken and Drell but beware that it is not for
amateurs.  I won't even mention Itzykson and Zuber!)

You will find that serious attempts at quantizing photons in a rigorous way
actually treat the photon as massive (to elimate certain problems which 
arise from gauge transformations) and then discard the unphysical part of the
resultant fock-space which results from the unphysical degrees of freedom.
(The phrase "Buela-Gupta quantization" pops into my head.)  The massiveness
in no way interferes with the photon's quantization or its behavior in the
classical limit.

-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
Newsgroups: sci.physics
Subject: Re: Twins Paradox Resolved
From: mcirvin@husc10.harvard.edu (Mcirvin)
Date: 28 Jul 92 15:26:27 GMT

throopw@sheol.UUCP (Wayne Throop) writes:

>> From: metares@well.sf.ca.us (Tom Van Flandern)
>> Message-ID: <BrrztE.J4u@well.sf.ca.us>
>> 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. 

>This is so clearly wrong that I suspect I'm missing Tom's point
>altogether.  The "rate of progress of time (and distance)" of
>a fast-moving traveler is identical whether "moving away" or
>"approaching". 

Perhaps the problem here is the meaning of "apparent."  Tom
van Flandern might be talking about what the observer actually
*sees* looking at emitted light from the traveler, not what
rate is calculated after taking signal delays into account.
If I'm traveling toward you at a rate close to c, in your frame
I'm close on the heels of my emitted light.  You see me start
my trip just before I arrive at your position, and my clock
*appears* to be sped up.  Now, if you know that light has a
finite speed and take that into account, you'll find that
my clock is actually slowed down by the usual factor. 

Likewise, if I'm traveling away from you, you see my clock
slowed down to an even more extreme extent than time
dilation implies, because the signal delay is getting longer
and longer as I go.

An interesting exercise is to examine how fast the traveling
and stationary twins' clocks *look* to each other in the
traditional twin-paradox situation, and to see how the
elapsed apparent times add up to the correct ratio.

-- 
Matt McIrvin  mcirvin@husc.harvard.edu 
Newsgroups: sci.physics,sci.philosophy.tech,talk.religion.misc
From: ewald@math.lsa.umich.edu (Brian Ewald)
Subject: Re: Noah's formation: The rainbow
Date: Thu, 23 Jul 92 17:12:09 EDT
Organization: University of Michigan, Mathematics Department, Ann Arbor
Distribution: sci

In article <2A6DEF17.1804@ics.uci.edu> bvickers@ics.uci.edu (Brett J. Vickers) writes:
>peterk@public.sub.org (Peter Kittel) writes:
>>Is it only me or does the sky beneath a rainbow also appear lighter
>>to others than the sky above a rainbow (or wait, was it the other way
>>around?)? But anyway, for my eye there is definitely a jump in
>>brightness of the background sky (normally rain clouds) from beneath
>>to above the rainbow. Any explanation for this?
>
>Optical illusion?  Two fields of the same color, separated by a line
>of a brighter or darker color, give the optical illusion that one half
>is lighter than the other.  The trick is to cover the line and see that
>they are the same.  I've never tried this with a rainbow.
>
>--
> ___            _    _     _  _        _
>(  _) ___ ___ _( )__( )_  ( )( ) o  __( ) _  ___  ___  ___
>(___)(_) (__=) (_)_ (_)_   (__) (_)(_((_)(_'(__=)(_) _(_)
>Brett Vickers (bvickers@ics.uci.edu)

It isn't an illusion.  The darker band of sky between the primary and
secondary rainbows is called Alexander's Dark Band, after Alexander
of Aphrodisias who noted it around the year 200AD.  (The secondary
rainbow is the often seen rainbow above the primary, about twice as
wide, on average one tenth as bright, and with the colors apparently
reversed; it is caused by an extra reflection).  The bows themselves
are caused by the light going through the angle of minimum refraction
in the water droplets, although some, albeit considerably less, is
refracted more.  With the primary rainbow, this is beneath the rainbow,
with the secondary, it is above.  Therefore the sky between the two
bows is, in fact, darker.

Brian D. Ewald
ewald@math.lsa.umich.edu
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Instant Communications
Date: 31 Jul 92 20:07:56 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

Snarfy writes:
        Now  , back to current draw.  Again, Kirschoff's law states that
       at a junction I(in) = I(out)  .   Since  a  junction  is  usually
       considered  to  be  a  place  where three conducting elements are
       joined , consider a system of a transmitter 18.63  miles  distant
       from  two  receiving  antennas  .   At  resonance , the receiving
       antennas each ``drain'' 1/10  of  the  available  output  of  the
       transmiter. The rest of the transmitter's energy is ``wasted'' on
       heating  the atmosphere or distant intergalactic nebulas.  If one
       of the antennas is suddenly oriented away from  the  transmitter,
       the  same  mass  still  stands  between  the  transmitter and the
       distant galactic nebula and the atmosphere  beyond  the  antenna.
       The  entire  resonant  system is now detuned ,however, because of
       the effective removal of one of the inductive elements  from  the
       system.   If  the effect of this detuning took the time necessary
       for light  to  traverse  the  18.63  miles  to  register  at  the
       transmitter,  then  you  would have a violation of Kirchoff's law
       which  endures  for  .1  milliseconds  (  a  virtual  eternity  ,
       leptonically speaking).

Snarfy, you ding-dong, you're saying that the current at the receiver
is not equal to the current at the transmitter.  Right.  If you are
going to consider the Xmttr-Rcvr pair (or triad) as a current loop
of a circuit, you had better consider the circuit element that
connects the transmitter and the receiver - the electromagnetic
radiation (which fills a lot more space than just between the
antennae, which is where the extra energy goes).  At any individual
point between the two, no violation of Kirchoff's Law occurs - the
disturbance in the EM field back-propagates from the antenna with
speed c.

Ben
Newsgroups: sci.physics
From: gilligan@bldrdoc.gov (Jonathan Gilligan 303-497-3861)
Newsgroups: sci.physics
Subject: Re: "What's New" July-24-1992
Date: 31 Jul 92 00:43:57 GMT
Organization: National Institute of Standards and Technology

In article <1992Jul29.024403.5319@murdoch.acc.Virginia.EDU> crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:
|>>Yea, those astrologers might be after our vital bodily fluids. Come on
|>>Dale, this is farther then even you normally stretch a point. I have
|>>seen letters from the APS to newspapers asking them to put disclaimers
|>>on horoscopes. 
|>
|>     Where?  When?  Publicity?  Studies?  Commissions?
|>
|>     The position of the APS is that the space station is not 'science'
|>     and should not be funded as such.   I would just expect them to pursue 
|>     other 'science purity' issues with the same vigour.
|>

I missed the APS action on horoscopes, but one of the fora (Science
and Society, I think) gave an award to James Randi a little while ago
for his work debunking claims of extrasensory perception and telekinesis.
Randi is currently being sued by Uri Geller for saying that Geller cannot
bend spoons with his psychic powers.

---Jon
-- 

Disclaimer --- The government probably disagrees with my opinions.
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: mind-numbing gedankenexperiment
Date: 24 Jul 92 18:22:06 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

mitsu@nic.cerf.net (Mitsuharu Hadeishi) writes:
>I don't think anyone fully understood the import of the communication from
>Dr. Jack Sarfatti I posted a few days ago.  Let me summarize it first.

Really, sir, I did read it.  I just didn't think it was worth
respondiing to.

>It has widely been asserted that the non-local correlations evinced in the
>EPR paper and most recently verified conclusively in the Aspect experiments
>in France, though very strange, cannot be used for communication.  However,
>the demonstrations to this effect rely on non-unitary behavior of the
>detectors (i.e., probability current is not conserved).

wha?  They do nothing of the sort.  As was best said by somebody else,
operators separated by spacelike intervals commute.  They can't
influence each other.  QED.  (that's quod erat demonstratum, not
quantum electrodynamics)

> [Sarfatti quote] the transmitter photon retarded wave arrives at T and is
> detected. Information on the setting of the transmitter at event T is
> sent backwards-in-time by an advanced transmitter photon wave. The
> advanced wave arrives at S just as the photon pair is being emitted.
> This is what Fred Hoyle calls a "loop in time" between events S and T.

This is meaningless.  What is an "advanced photon wave"?  I think 
Sarfatti is trying to talk about advanced and retarded in the sense
of potentials in electrodynamics.  As we have probably all beaten to
death, even though you can use the advanced potential, which is
seemingly non-causal, to do calculations, causality is never actually
violated.  Hell, in the Coulomb gauge the potential propagates
instantaneously, but it doesn't allow instantaneous communication.
(The fields are limited to lightlike propagation.  See Jackson,
especially problem 6.19, nyuk nyuk.)  I hate to say this, because he
was so distinguished, but it is becoming impossible to treat anything 
Fred Hoyle says with any respect.  He is an example of the tragic
results of failing to accept that you can be wrong.

> [Sarfatti again]  I have algebra based on Feynman rules to back
> up every detail of what I am talking about intuitively here. This is
> not handwaving.

And I'm the King of England.

Ben Weiner
("Weiner" is not a particularly Hanoverian name.)
From: gr1c+@andrew.cmu.edu (Greg Howard Rhodes)
Newsgroups: sci.physics
Subject: Magnetic lenses
Date: 28 Jul 92 16:33:06 GMT
Organization: Junior, Physics, Carnegie Mellon, Pittsburgh, PA

Well, as a senior undergraduate physics student, I feel that I should know
the answer to this, but my optics are not all they should be...(and with the
GREs coming up really soon, too...)

Anyway, I just got glasses. Being able to see and all is great, but I started
wondering about alternatives. Now, sure there all of the contact lenses and
the like, and maybe even lenses designed to actually _fix_ your vision. But
I was thinking about something a bit more esoteric.

Would it be possible to use a strong stationary E and/or M field to bend
light in such a way to mimic an eyeglass? And if it would be possible, how
strong would the field have to be? (and, from a consumer standpoint, how 
small could it be made?

Just wondering, and hoping that the enivronmental thread gets off of 
sci.physics in my lifetime.

Greg Rhodes                     She's the puzzlepiece behind the couch
gr1c@andrew.cmu.edu             That made the sky complete. -- Lemonheads
Newsgroups: sci.physics
From: ttyytt@mixcom.com (Adam Costello)
Newsgroups: sci.physics
Subject: Re: Air bubbles in a universe of water
Date: 21 Jul 92 00:10:43 GMT
Article-I.D.: mixcom.1992Jul21.001043.10436
Organization: Milwaukee Internet Xchange BBS, Milwaukee, WI U.S.A.

In article <l6h6h3INNo37@news.bbn.com> saustin@bbn.com (Steve Austin) writes:
>ttyytt@mixcom.com (Adam Costello) writes:
>
>->Here's another.  A man sitting in a boat on the lake pulls a plug
>->in the bottom of the boat.  The boat begins to sink slowly, and eventually
>->comes to rest on the bottom of the lake, completely submerged.  Describe
>->(qualitatively) the level of the lake as a function of the position of the
>->boat.
>
>Okey doke.  These things are real easy to do if you imagine special
>cases of boat and then rationalize that the shape of the boat does
>not matter to the problem.
>
>Imagine the lake was a cylinder filled with water and that the boat was
>cylinder with only slightly smaller diameter.  The boat it made with
>a thin foil that has non-negligible weight.  When the boat is placed
>into the lake, the water will shoot up the sides of the cylinder lake.
>When the boat is submerged the water level will be only slightly higher
>than it orininally was.
>
>When the boat is sinking, the water level will drop until the boat is
>submerged,  Thereafter there will be no change in the water level.

Almost.  The water level will not change while the boat is sinking, until
the water starts pouring into the boat over the side (as opposed to
coming in through the hole in the bottom).  Then the water level will go
down at the same rate as the boat, until the boat is full of water.

AMC
Newsgroups: sci.physics
From: stu5s33@bnr.ca (Robert Nychka)
Subject: Energy-Mass attraction.
Summary: mass
Keywords: mass
Reply-To: stu5s33@bnr.ca
Organization: Bell Northern Research Ltd
Date: Fri, 31 Jul 1992 18:32:20 GMT

There is something that I have always wondered but have never found in any of the popular science magazines or heard in a lecture.  Is a gravitational field produced by mass or energy ? 

In refering to the equation :

E^2 = (mc^2)^2 + (pc)^2

Is it the rest mass that produces a graviational field or mass combined with it's momentum ?

Does the relativistic mass generate a gravitational field which is also relative to the observer ?  Is a stronger gravitational field generated as an object is accelerated from an observer as a result ? Does GR take this into account ?

Curious...
Robert Nychka
From: O.MostynOwen@cs.ucl.ac.uk
Newsgroups: sci.physics
Subject: how do you do the one about an infinite mesh of 1ohm resistors ...
Date: 24 Jul 92 15:03:14 GMT


There's a problem I was told about years ago which I never managed to solve:

You've got an infinite 2D grid if 1 ohm resistors. What's the resistance
across 1 of them (no it's not 1ohm, 0 or infinity).

                              .
                              .
                              .
                              .

              |                  |                   |
              |                  |                   |
         ------------1ohm-----------------1ohm------------
              |                  |                   |
              |                  |                   |
 .....      1ohm               1ohm                1ohm     .....
              |                  |                   |
              |                  |                   |
         ------------1ohm-----------------1ohm------------
              |                  |                   |
              |                  |                   |

                              .
                              .
                              .
                              .

The only clue I got was that you could solve it using Fourier Transforms.
Anyone remember seeing a solution?  

I'd be grateful if someone laid this one to rest since it keeps on coming
back to haunt me.

-----------------------------------------------------------------------------
Owen Mostyn-Owen                                     +44 71 387 7050 ext 3687
Internet: omostyno@cs.ucl.ac.uk   UUCP: ...!{uunet,uknet}!ucl-cs!O.MostynOwen
Computer Science, University College London, Gower Street, LONDON WC1E 6BT
Newsgroups: sci.physics
From: pbond@spitws100.sbil.co.uk (Philip Bond)
Subject: Re: Twin Paradox
Reply-To: pbond@spitws100.sbil.co.uk
Organization: Salomon Brothers, Ltd.
Date: Tue, 21 Jul 92 11:04:41 GMT

In article 3031@galois.mit.edu, jbaez@riesz.mit.edu (John C. Baez) writes:
>In article <1992Jul16.100622.13764@vax5.cit.cornell.edu> cpyy@vax5.cit.cornell.edu writes:
>
>>I asked this same question in a past physics class.  The reference frames
>>are not equivalent.  The one twin actually can feel himself accellerating,
>>while the other cannot.  Funny, I asked, "Then relative speed is not what
>>actually causes the aging--it's the acceleration?"  The physics professor,
>>who was highly respected, replied, "Yeah, it has something to do with
>>the acceleration."
>
>One way to stay highly respected is to know when to be vague.  :-)
>Indeed the aging has "something to do with" with the acceleration, but -
>if our twins were in a closed universe, say R x T^3 with its standard
>flat metric (here I mean that space is a torus and time is a line), and
>one stood still while the other went around the universe (relative to
>the standard coordinates on R x T^3), then the one who went around would
>be younger when they met again, even though NEITHER experienced any
>acceleration.  (Of course I'm assuming that our travelling twin was BORN
>at a high velocity.  Technical details left to NASA.)
>
>Of course this twist is less relevant to reality since nobody knows if
>the univser is closed, and certainly nobody has circumnavigated it.
>Nonetheless, it shows that one has to be careful.


It is amazing how the twins paradox lives on, and causes problems.
Even to "highly respected" physics professors it seems. Of course,
you CAN compute the effect of the acceleration ( it is a General
Relativistic effect ), and this has been done ( for the experiment 
when a couple of 'planes carrying atomic clocks circumnavigated 
in opposite directions ). The GR effect is definitely second-order.
The basic effect being measured is one of relative velocities ; just
draw a space-time diagram and it is obvious what's going on. 
The twins paradox was not intended by Einstein to illustrate GR but
SR effects. The acceleration is for all intents and purposes irrelevant.


	IMHO , usual disclaimers apply,

	Phil.