HDTenEightyP/NetNews huggingface dataset:
From: jcf@world.std.com (Joseph C Fineman)
Subject: Re: Liquid metals
Organization: The World Public Access UNIX, Brookline, MA
Distribution: sci.physics, sci.chem
Date: Wed, 13 Jan 1993 02:52:54 GMT

Nothing so strenuous as that is needed to freeze Hg; its m.p. is -39 C
(that's one of three ways you can tell that it's -40 out: the Hg
freezes in the thermometer, your spit crackles when it hits the
ground, and the F & C thermometers read the same).  The real question
is why the m.p. is so low.  I don't know.  The theory of the m.p. of
metals must be pretty subtle, since the kernel of an atom (i.e. the
atom minus its valence electrons) is spherical & can't notice when the
relative directions of its neighbors are disturbed.  I suspect it may
depend on non-nearest-neighbor interactions.

P.S.:  Also at -40 C (or F), deciduous trees are killed; north of
the -40 winter isotherm, the climax forests are evergreen.  I myself
have never experienced that temperature.
-- 
        Joe Fineman             jcf@world.std.com
        239 Clinton Road        (617) 731-9190
        Brookline, MA 02146
From: sichase@csa1.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: "SPIN," Micro- vs. Macroscopic . . . .
Date: 7 Jan 1993 17:09 PST
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: world
NNTP-Posting-Host: 128.3.254.196
News-Software: VAX/VMS VNEWS 1.41    

In article <1ii9krINNivt@gap.caltech.edu>, allenk@ugcs.caltech.edu (Allen Knutson) writes...
><CCB104@psuvm.psu.edu> inquires:
> 
>>What's the difference between the spin of a globe or
>>disk (e.g. beachball or frisbee), say, and the spin of an
>>electron, photon, phonon, Bloch spin wave, proton, etc.?
> 
>One's quantized and the other isn't (in an infinite universe).
>Luckily, I can give (part of) a more useful answer.

What makes you say that the spin of a beachball is not quantized?  It most
certainly is, though you will never design a clever enough experiment to 
measure the quantization, given the huge number of spin quanta contained in 
the typical beachball.

Just because QM goes nicely over to classical Newtonian mechanics, 
*on average*, in the appropriate limit, does not mean that quantization 
turns off - merely that it becomes insignificant to the dynamics.

-Scott
--------------
Scott I. Chase			"It is not a simple life to be a single cell,
SICHASE@CSA2.LBL.GOV		 although I have no right to say so, having
				 been a single cell so long ago myself that I 
				 have no memory at all of that stage of my 
				 life." - Lewis Thomas
Newsgroups: sci.physics
From: panoff@hubcap.clemson.edu (r m panoff)
Subject: Surface Tension Measurements
Keywords: Surface tension
Organization: Clemson University
Date: Fri, 8 Jan 1993 20:31:52 GMT


A middle school teacher has been asking about simple measurements
of surface tension.  Is there a simple lab device that one can use to
measure various liquids?  Does anyone know of a simple lab setup that
can be done in the average middle school lab?  What kinds of hands-on
explorations of surface tension ought to be suggested?  Any references
appropriate for this level?

Send any helpful comments, answers, suggestions, pointers directly to
me at:  rpanoff@ncsa.uiuc.edu (note different from posting address)
or directly to the middle school teacher: pedersen@cardinal.ncsc.org

Thanks in advance for all your help.

Bob Panoff
-- 
rmp, for the Bob's of the World
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Faster then the speed of light?
Date: 8 Jan 93 22:23:01 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

cburke@nexus.yorku.ca (Carolyn Burke) writes:

>In a recent talk I attended, the speaker mentioned a series of
>astronomical observations involving quasars.  Please excuse my
>use of lay-terminology.  The speaker said that using triangulation
>calculations to determine the velocities of two such heavenly objects
>relative to each other over a period of time, scientists observed (or
>inferred) that said relative velocity far exceeded the speed of light,
>in excess of between 400% and 700% ...

This is a well known phenomenon generally called "apparent superluminal
beaming" or something like that.  Richard Mathews's post explained it
but I thought a diagram would help.

        A ------------------------------------------------ C
          -                                     -
             -                        -
                -          -
                   B

Suppose B is moving away from A at high speed (few-tenths of speed of light)
and we're sitting very far away at C.  Because B is closer to us light from
it gets here faster than light from A, so at a given time on Earth (C) we
are seeing an "old version" of A compared to B, and it looks as if B has moved
away from A at a speed greater than that of light.  Some astrophysics texts
have more detailed explanations.  This is perfectly consistent with the
usual interpretation of quasars, regardless of what others might be saying.
From: dseeman@novell.com (Daniel Seeman)
Newsgroups: sci.physics
Subject: Re: sci.physics.research: Are there important unresolved issues?
Date: 12 Jan 93 01:09:36 GMT
Organization: Novell Inc., San Jose, Califonia

In article <1993Jan11.223445.13105@galois.mit.edu> jbaez@riesz.mit.edu (John C. Baez) writes:
>
>Sean Merritt writes:
>
>>As I stated before I object to one memeber of the panel. Now I find that
>>after the discussion I also don't have much confidence in Baez to
>>perform as a "filter" if articles in sum are to be considered as
>>ensembles of indistinguishable particles. Nevertheless I feel that he
>>and Dale may have some "constructive ineterference" efffect and 
>>all my objections may be for nought.(see below)
>
>Could you provide a more specific and less metaphorical explanation of
>why you no longer have confidence in my abilities as a filter?
>Certainly if a majority of people think I'm being unduly harsh on
>articles about interpretation of QM, I will gladly recant (as I mentioned).

This is an illustration of the problems to come.  "You" (the moderator) will
recieve a number of objections concerning a refusal to post something.  Or
rather "you" may get mail detailing why your QM interpretations are too harsh
and "you" will be forced to "...gladly recant..."  

Well in the time it takes to convince "you" that "I" do not agree and that you
should recant, a number of things have happended.  First, probably the arguement
concerning why "you" are too harsh is a good one to post publicly.  Second 
during the "convincing time" other articles may have been left unposted.  In
deed, "you" may actually see the logical error and have mis-givings about all
the articles that were not posted in the past.  Remember all is 20/20
in hind-sight.

dks.
Newsgroups: sci.physics,news.groups
From: sawyer@utahep.uta.edu (Lee Sawyer)
Subject: Re: sci.physics.research: Are there important unresolved issues?
News-Software: VAX/VMS VNEWS 1.41    
Organization: University of Texas at Arlington High Energy Physics Group
Date: Sun, 10 Jan 1993 20:53:00 GMT

 HI Leigh,

  You asked two questions : What are the moderators own killfiles, and why are 
there no women on the "board". 
1) I usually don't use killfiles - actually, if you recall a series of posts
 before Christmas, I have trouble getting them tuned correctly for VNEWS. 
 The only entry in my sci.physics killfile is for the TIME HAS INERTIA thread.
2) In answer to both your second question, and the question of why no materials
 physicists, I asked Matt to contact at least one solid state physicist, who 
 would also have met the gender requirement. She declined to be a comoderator.

  You said only one moderator had an advanced degree in physics. I have a PhD in
physics, I believe Bill Johnson's PhD is in Physics, Baez has a PhD in math
I believe but does theoretical physics research. Only Dale is lacking a PhD
at the moment. 

  Lastly, I have mostly skipped the haranguing over the panel. I was asked to do
this and agreed, because I feel a moderated group will draw more researchers 
into the discussions, and hopefully expand the use of the net as a scientific
tool. I have neither the time nor inclination to play net.god, nor to justify
my research credentials by creating an elitist newsgroup where only the elect
few can join the discussion. We are moderators, not redactors. 

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

         Dept of Physics                          
         Univ. of Texas                            
               at Arlington
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Newsgroups: sci.physics
Subject: Re: Wavelets & Coherent States ?
Date: 7 Jan 93 02:19:47 GMT
Distribution: usa
Organization: University of Virginia

In article <1993Jan6.230830.6733@galois.mit.edu> jbaez@riesz.mit.edu (John C. Baez) writes:
>In article <1993Jan3.211626.3723@EE.Stanford.EDU> siegman@EE.Stanford.EDU (Anthony E. Siegman) writes:
>>In article <qg62r5g@rpi.edu> sassoj@aix.rpi.edu (John J. Sasso Jr.) writes:
>>
>>>quantum mechanics.  Although I have has a basic course in Q.M., can anyone
>>>explain to me what coherent states are?  Do they have anything to do with 
>>>phase-space localization?
>>
>>   I also think you are perceptive in noting a possible connection
>>between wavelets and coherent states.  Coherent states provide an
>>"over-complete" basis for the SHO, which means that the expansion of a
>>given arbitrary SHO state in coherent states is not unique (although
>>there are preferred ways to do the expansion), and I suspect the same
>>may be true of wavelets.
>
[stuff deleted]
>
>Coherent states are rather different.  They don't form a basis; they are
>"overcomplete".  Basically, they are just functions of the following
>form: a Gaussian translated by a certain amount and then multiplied by a
>complex exponential.  If we make the Gaussian tall and skinny, we have a
>function that's fairly well localized in position space; if we make it
>short and wide, it's fairly well localized in momentum space.  If one is
>looking for a quantum state that approximates a given classical state,
>one is probably looking for a coherent state... they are often used for
>that in quantum optics.  

      And the wavelet people call these 'frames'.  They are not required
      to be orthogonal and can be thought of as a generalization of 
      a wavelet basis.   The only reference that seems to be handy
      is Heil and Walnut's article in SIAM Review (31:628 (1989)) 
      which is right after Strang's introductory article on wavelets 
      and dilation equations.  I believe that 'Wavelets and Their
      Applications' has some relevant articles explicitly pointing
      out the connections between coherent states representations and
      wavelets, but I cannot seem to find the book in the mess.

                               dale bass

-- 
C. R. Bass                                          crb7q@virginia.edu        
Department of Wildebeest
Transvaal                                           (804) 924-7926
Newsgroups: sci.physics
From: bhv@areaplg2.corp.mot.com (Bronis Vidugiris)
Subject: Re: A proof that quantum mechanics is an incomplete theory
Organization: Motorola, CCR&D, CORP, Schaumburg, IL
Date: Tue, 5 Jan 1993 18:14:11 GMT

Using the simple principle that QM generally predicts what classical 
experiments based on Maxwell's equation would indicate, phrased in terms
of particle probabilities rather than radiation intensities, I predict that
the time delay between a polarizer changing and the change in proability of
detecting the particle will be equal to t =  d / c, where d is the distance
the light travels from the polarizer to the detector.  This assumes the
polarizer is very thin.

To consider what one would expect if the polarizer is not thin is more
complex.  As a thought experiment, imagine that one shines a beam of
polarized light on a thick rotating polarizer and measures the intensity of
the light with a detector at some distance 'd' away.  One would expect
to be able to treat such a thick polarizer as a series of thin polarizers,
with the total transmission probability being the multiple of transmission
through the thinner polarizers.  One would also expect the light to travel
at the speed of light with the associated delays.  In the limiting case, if
the polarizer is rotating so rapidly that it makes a 90degee turn while the
light is passing through it, one would predict no light transmission at all 
(assuming a perfect polarizer).

Exactly how one formulates this problem formally in QM I leave to someone
else, but I'm fairly sure it won't predict anything different than what
one would expect from 'classical' Maxwell's equations-style theory.

Obviously there *are* some differences in *some* predictions between QM and
Maxwell's equation type theories (such as the photoelectric effect), but I
don't think this experiment is one of them.  YMMV.

Newsgroups: sci.physics
From: chuck@stratus.drexel.edu (Wombozni Klik)
Subject: Re: Question on Mechanics Books
	<00966451.3A4F4300@uinpla.npl.uiuc.edu>
Organization: Drexel University Department of Physics
Date: Fri, 8 Jan 1993 16:15:53 GMT
X-Posted-From: stratus.physics.drexel.edu
NNTP-Posting-Host: sol.ctr.columbia.edu


I have both Marion (1st editon) and Goldstein (which I bought but
haven't used officially in a class). The book my prof used was Landau
and Lifshitz, a very thin book that I like a lot and has helped me
quite a bit. My instructor used this, telling us that "Goldstein puts
him to sleep", but near the end of the term covered some stuff from
the back of Goldstein without telling us...

Chuck
--
Chuck Browne                            | Frisbeetarianism: The belief that  
Drexel University Department of Physics | when you die, your soul goes up
chuck@nimbus.physics.drexel.edu         | on the roof and gets stuck.
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Newsgroups: sci.physics
Subject: Re: bubble in container
Date: 5 Jan 1993 00:08:46 GMT
Organization: Intel Corp., Chandler, Arizona
NNTP-Posting-Host: stealth.intel.com

In article <1993Jan4.170325.27320@novell.com> dseeman@novell.com (Daniel Seeman) writes:
>>bhoughto@sedona.intel.com (Blair P. Houghton) writes...
>>>The pressure in the bubble can not change unless the number
>>>of atoms of gas change, the temperature of the bubble
>>>changes, or the volume of the bubble changes.
>
>What if you cool the bubble.  Does the pressure change then?

Yep.

But the volume can't change.

The only way for the fluid to alter the pressure in the
bubble is to compress it or expand it, but since the fluid
is incompressible it can't do either of those.

If you heat or cool the bubble (or the bubble and the
fluid) you change the pressure of the entire container.

If you expand or contract the entire container, you change
the volume of the entire container, which changes the volume
of the bubble, which--if the temperature isn't simultaneously
changed--means you change the pressure of the entire container.

If you add gas to or remove gas from the bubble, you change
the pressure of the entire container.

Moving the bubble around in the container accomplishes
none of these, and therefore does not change the pressure
anywhere in the container, unless the change in pressure
is accompanied by a change in the temperature of the gas
(which, come to think of it, we haven't really ruled out,
but we've given no mechanism for such a transfer of energy).

				--Blair
				  "'Pop!' goes the weasel..."
Newsgroups: sci.physics
From: mkagalen@lynx.dac.northeastern.edu (michael kagalenko)
Subject: Advise needed
Organization: Northeastern University, Boston, MA. 02115, USA
 
Date: Sat, 9 Jan 1993 04:05:19 GMT

What Graduate level books about conformal invariance applications in
physics (with intro to said invariance) would you wizards recommend ? 
Thank you.

Newsgroups: sci.physics,alt.sci.physics.new-theories
From: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: Wavelets, squeezed states 12: Wavelet Transform.
Organization: Whole Earth 'Lectronic Link
Date: Tue, 12 Jan 1993 06:01:32 GMT


12. The window called "the basic wavelet" is scaled for waves of different
frequencies. Introduce a =/ 0 and define

h[a,s](t) = |a|^-1/2 h((t-s)/a)    (85)

*Note -earlier I did not distinguish "||...||" from "|..|" - the integrals
of |...| are ||..|| - so some of earlier formulae have to be corrected. I
will use correct notation from now on as those earlier formulae recur.

||h[a,s]||^2 = Integral(-+inf)[dt|h[a,s](t)|^2]= ||h||^2   (86)

* a can be, and must be, under some conditions, negative real.

Classically h and f are real - take them as complex and take real part as
in classical wave theory. In QM h and f are really complex - do not take
real part only.

Define the wavelet transform as

F(a,s) = <h[a,s]|f> = Int(-+inf)[dt|a|^-1/2 h((t-s)/a)* f(t)]  (87)

where * means complex conjugate (cc).

This wavelet transform also localizes signals (i.e., time-series of complex
systems - possibly chaotic with fractal attractors in phase space) in the
time-frequency plane (i.e. phase space).

First look at localization in time. If the window h(t) is concentrated near
t = 0 ( drop requirement of window with compact support), then F(a,s) is a
weighted average of the signal f(t) around t = s.

*The weight function is not generally positive so you cannot think of it as
a classical probability density - wavelets demand a kind of "negative
probability density" in a naive sense (e.g. Wigner phase - space function).

Next look at the localization in frequency. Like the earlier windowed
Fourier transform, the wavelet transform has rigid time-translations of the
window looking like a convolution. For example, let f(t) be the Dirac delta
function. The Green's function impulse response is then

ga(s) = |a|^-1/2 h(-s/a)*    (88)

F(a,s) = (ga*f)(s)  (89)

Now the * is a convolution in eq. 89 but it is cc in eq. 88. A limit on
text files. The context should make clear which is which.

Ga(v) = Int(-+inf)[dt e^i2pivt |a|^-1/2 h(-t/a)*] = |a|^1/2 H(av)*  (90)

A window h(t) with compact support in a finite band vmin < v < vmax have
convolutions called "bandpass filters" that pass only frequency components
of the signal in the band.

The wavelet transform F(a,s) only depends on those frequency components of
the original signal f(t) in the band vmin/a < v < vmax/a if a > 0, or
vmax/a < v < vmin/a if a < 0.  Thus frequency localizations, unlike the
windowed Fourier transform, is achieved by "dilations" rather than
translations in frequency space. Remember, the wavelet transform still uses
rigid time translations of the window, but it does not use translations in
frequency space.

Consider the example of audio signals. We perceive "meaning" (logarithmic
response) frequency ratios rather than simple linear frequency differences.
Hearing an octave difference is achieved by doubling the frequency. We also
"hear" linear frequency differences as "beats"  and there is also a
phenomenon of non-linear "difference tones" (p.46).

to be continued.




Newsgroups: sci.physics
From: a722756@roper.mc.ti.com (W. Donald Rolph)
Subject: Re: TIME HAS INERTIA   - STRICTLY FOR DEVOTED READERS OF: TIME HAS INERTIA
Originator: a722756@roper.mc.ti.com
Keywords:  Attention Mr. ELI HAWKINS
Organization: Texas Instruments / Attleboro Mass / USA
Date: Fri, 8 Jan 1993 14:03:44 GMT


I will point out for the record that one of the great powers of tradtional
languages is their ambiguity and complexity which allow the listener to discern
meaning perhaps not conciously understood by the speaker.

This is not what I want form my mathematics howver, and simple but rigorous
mathematical formulations I believe have much more power for the issues we are
discussing.
-- 

Regards.
 
Don Rolph  a722756@pan.mc.ti.com WD3 MS10-13 (508)-699-1263
From: jonathan_scott@vnet.ibm.com (Jonathan Scott)
Date: Fri, 8 Jan 93 12:06:48 GMT
Newsgroups: sci.physics
Subject: Re: Faster then the speed of light?
News-Software: UReply 3.1
            <richard.726455490@astro>

>If an object is moving almost directly towards you at almost the speed
>of light ...

One idea to explain the observed "superluminal velocity" effect around
several quasars was that the observed regions are simply where
"searchlight" beams from the central quasar are illuminating clouds, so
as the beams sweep across the cloud the illuminated region can easily
move faster than light.  This requires some statistically unlikely
geometry to explain the number of cases observed so far.

Another idea was that the superluminal relative velocity is explained by
assuming that the observed regions (which for example may be emitted
clouds rather than the quasars themselves) are indeed travelling towards
us at significant fractions of the speed of light.  This begged the next
question which is of course WHY so many of the brighter quasars seem to
be indulging in this geocentric behaviour, and the standard answer is
that for some reason these regions appear brighter in the direction in
which they are moving.  (Earlier explanations involving brightening due
to blue-shift of motion weren't entirely successful).

Those of us without such persistent faith in the existence of black
holes have an easier time, because super-massive star-like objects with
a well-defined surface and a significant gravitational component in
their redshift can be smaller, closer and a much more plausible
explanation of quasars.  The receding sources are then simply clouds of
material being blown off at less than the speed of light.

I think there are good grounds for remaining sceptical about black holes.
As far as I know, the most sensitive tests of GR to date (using the
precession of Mercury and the binary pulsars) have mainly confirmed the
factor 2 in front of (Gm/r)**2 in the time coefficient for the isotropic
metric in the PPN approximation form (1 - 2Gm/r + 2(Gm/r)**2).  This
approximate coefficient doesn't even give black holes at all (since it
is always positive) and neither does the simplest extension of Newtonian
potential theory to match SR, which gives exp(-2Gm/r) for the same
coefficient, matching the GR results to the same approximation.

Quasar controversies and whether black holes exist are popular subjects
for astronomy newsgroups, and occasionally for this one too, so you can
probably find more information in previous postings.  I'm not very up to
date in this area, so if anyone can provide an authoritative FAQ-style
summary of the latest findings, I for one would be interested to know.

Jonathan Scott
jonathan_scott@vnet.ibm.com  or  jscott@winvmc.vnet.ibm.com