HDTenEightyP/NetNews huggingface dataset:
From: dseeman@novell.com (Daniel Seeman)
Newsgroups: sci.physics
Subject: Re: Yet Another Preposterous Post
Date: 7 Jan 93 16:29:52 GMT
Distribution: sci
Organization: Novell Inc., San Jose, Califonia

In article <HAGERMAN.93Jan6174824@rx7.ece.cmu.edu> hagerman@ece.cmu.edu (John Hagerman) writes:
>paul@mtnmath.uucp says:
>
>"Requires" is pretty strong, and invites a reactionary response.  But
>that's why sci.physics is so much fun, right?
>
>Here's the chain of thought that I think leads to posts about collapse
>being real.  "QM is a good theory, but it has a flaw (it includes the
>concept of instantaneous collapse, which is cause for concern).  But
>rather than consider it a flaw, what happens if we make it a postulate
>and explore the implications?  That's what Einstein did with the speed
>of light, right?"  The first step is easy, and leads to posts.  The
>second step is hard; perhaps beyond most readers of sci.physics, but
>surely not beyond the experts. 

For the record, I take exception to that remark about this information being
"...beyond most readers...(except) experts..."  Remember, if a subject is too
difficult for the instructor to teach, probably the instructor does not under-
stand the material herself.

Your audience is well educated, don't forget that...

dks.
Newsgroups: sci.physics
From: atems@igor.physics.wayne.edu (Dale Atems)
Subject: Re: hidden variables
Organization: Wayne State University, Detroit, MI
Date: Mon, 11 Jan 1993 03:17:33 GMT

In article <483@mtnmath.UUCP> paul@mtnmath.UUCP (Paul Budnik) writes:
>
>Let me quote Eberhard (page 76):
>	
>	Let us consider two measuring apparatus located in two different places
>	A and B. There is a knob 'a' on apparatus A and a knob 'b' on
>	apparatus B. Since A and B are separated in space, it is natural to
>	think that what will happen in A is independent of the setting of
>	the knob 'b' and vice versa. The principles of relativity seem to
>	impose this point of view if the time at which the knobs are set and
>	the time of the measurements are so close that, in the time laps,
>	no light signal can travel from A to B or vice versa. Then, no signal
>	can inform a measurement apparatus of what the knob setting of the
>	other is. However, there are cases in which the predictions of quantum
>	theory make that independence assumption impossible. If quantum theory
>	is true, there are cases in which the results of the measurements in A
>	will depend on the setting of knob `b' and/or the results of the
>	measurements in B will depend on the setting of the knob a.

Consider the Stern-Gerlach-type experiment described in my other
post. Clearly that situation is not as simple as implied by Eberhard's
argument. It is not a case of getting one probability distribution
for spins measured at site 1 if the setting of magnet 2 is 40 degrees,
and another if it is 90 degrees. You have to use measurements from
*both* sites on members of a pair to observe the quantum correlations.
 
Is there a case where the nonlocality is as obvious and trivial as
this quote seems to imply?

------
Dale Atems
Wayne State University, Detroit, MI
Department of Physics and Astronomy
atems@igor.physics.wayne.edu
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Speed of neutrinos
Date: 12 Jan 93 20:48:42 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

Matt Austern writes:

>It is well established that the speed of the neutrino is *close to*
>the speed of light.  I don't know how precisely it has been measured.

>I suspect that the best measurement is probably from the SN1987a
>supernova: several groups detected neutrino bursts at roughly the same
>time as the maximum brightness of the supernova.  At this kind of
>distance, even a slight difference between the speed of neutrinos and
>the speed of light would have made a big timing difference.

True; and this argument can be extended - the various neutrino detectors
saw neutrinos with a certain spread in energy (maybe 8 MeV) over a small
timespan (few seconds?).  You can use this, and the known distance to
SN 1987a, to set an upper limit on the neutrino mass, (assuming the
neutrinos were all emitted at exactly the same time; if there is a spread
the mass limit gets lower yet).  This also gives you a lower limit on a 
neutrino's velocity (from E^2 = m^2 + p^2).  One nice thing about this
calculation is that it is independent of the details of supernovae,
neutrino flashes vs. light curves, etc.

For a 20 eV neutrino with 8 MeV energy, I get v = c * ( 1 - 3 x 10^-12 )
which is pretty close to 1, although this calculation comes with no
warranty, explicit or implied, of merchantability, fitness, or usability.
Newsgroups: sci.physics
From: mrmuon@next12pg2.wam.umd.edu (Eli John Hawkins)
Subject: Re: TIME HAS INERTIA     Gosh!
Organization: Workstations at Maryland, University of Maryland, College Park
Date: Thu, 7 Jan 1993 22:53:12 GMT

In article <abian.726296379@pv343f.vincent.iastate.edu> abian@iastate.edu  
(Alexander Abian) writes:
>    To me, my (A3) is the most convincing, i.e.,
> 
> (A3)    The primal cause of action of everything (from a particle to a
>         person to a planet  to a galaxy, animate or inanimate objects,
>         etc.)  is
> (A3)                GAINING A FEELING OF SECURITY

    Gosh Mr Abian, your's is truely an intelect of staggering proportions;  
indeed, the Plank length comes to mind. As itr happens, fundamental  
physics seeks to simplify our knowledge of the universe, and has thus far  
acheived a great deal of this through finding mathematical principles.
    Mathematics has the advantage of being truely simple. Mathematical  
constructions are built up from clear, unambiguous definitions. Emotions  
such as "a sense of security" may seem simple and fundamental to you, but  
they are not. I defy you to produce a complete explanation of your (A3)  
from precise axioms and definitions. I doubt that you can calculate the  
trajectory of a projectile based on (A3), other than by rewording the  
principle of least action.

>  The sooner Physics accepts (A3) the sooner Physics will reflect the
>reality.

    Your conceited attitude is quite uncalled for as you are in fact  
suggesting a huge leap backwards. "Your" (A3) bears a remarkable  
resemblance to the primite sort of "physics" that existed before Gallileo.  
As I recall, gravity was explained as a tendency for certain of the  
elements (earth and water) to seek their home, the ground, and for the  
others (air and fire) to seek their home in the sky. This has been  
outmoded for several hundred years, so get a clue.
--
Eli Hawkins : mrmuon@wam.umd.edu
Newsgroups: sci.physics
From: alison@wsrcc.com (Alison Chaiken)
Subject: Spin-statistics theorem? (Was Re: Advise needed)
Organization: W S Rupprecht Computer Consulting, Fremont CA
Date: Wed, 13 Jan 1993 05:16:42 GMT

Hmm, sounds like someone out there should be able to explain the
spin-statistics theorem.  That is: why are spin-(n + 1/2) particles
fermions, and spin-n particles bosons?  I have seen textbook
demonstrations that this is the case according to what type of Lie
group the particle transforms under, but I must admit I don't get it.
In particular, is there an intuitive explanation as to why spin-1/2
particles can't have a zero S_z state?  After all, zero is a possible
geometrical projection of 1/2, just as it is a possible geometrical
projection of 1.

Sorry to dredge up "1920's murk."  Guess I should have asked Vicki
Weisskopf when I was at MIT.
-- 
Alison Chaiken 				alison@wsrcc.com
(510) 422-7129 [daytime] 		or chaiken@cmsgee.llnl.gov
Look if you like, but you will have to leap.
From: gbshaw@rigel.cs.pdx.edu (Bert Shaw)
Newsgroups: sci.physics
Subject: Re: Simple Universe Question
Date: 12 Jan 93 04:46:37 GMT
Article-I.D.: pdxgate.6690
Organization: /etc/organization

<re "Simple Universe" with only a particle and an anti-particle>

As I recall, there's no way to have an electron-positron annhilation without a 
third body to carry off some momentum & energy.  (Can't balance all conserved
quantities without it.)  Isn't that right?

bert shaw	gbshaw@rigel.cs.pdx.edu <or>  70431.3014@compuserve.com
Newsgroups: sci.physics,alt.sci.physics.new-theories
From: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: Wavelets, coherent states and complex spacetimes 4
Organization: Whole Earth 'Lectronic Link
Date: Fri, 8 Jan 1993 07:56:13 GMT


4. Gerald Kaiser defines a "generalized frame" in abstract math that I will
not even pretend to understand or try to describe - but we will see if we
can decode a useful picture for simple-minded physicists. The math could
all be a big con-game to hood-wink us.

The frame is a set of vectors |m> and the canonical coherent states are a
"tight frame". T is a map from vectors of the Hilbert space to functions on
M. The resolution of unity is replaced by

G(N) = T*T = Integral over N[du(m)|m><m|]   (19)

where N is a subset of the set M whose elements are m. Does G converge? is
an issue.

If the frame is tight then we get a resolution of unity.

*It appears that if we want quantum connection communication we do not want
entangled states with "tight frames" that strangle the communication!*

A lot of obscure math that John Baez can slop around in follows but it
leads up to the enigmatic image of a "reproducing Kernel Hilbert space".
Along the way we have

K(m,m') = <m|G^-1|m>   (20)

which "has a property similar to the Dirac delta function with respect to
the measure du in that it reproduces functions in the space.." But K is
bounded unlike the Dirac function and the "test functions" that K
reproduces form a Hilbert space. K is an integral operator not merely a
distribution.

*M will become complex spacetime!*

g(m) = Integral over M [du(m)K(m,m')g(m')]  (21)

So we can begin to see that the imaginary part of space-time will be a
little like the momentum p of the harmonic oscillator. So these tight
frames may play some role in Hawking's version of quantum gravity needing
imaginary time?

to be continued
From: allenk@ugcs.caltech.edu (Allen Knutson)
Newsgroups: sci.physics
Subject: Re: "SPIN," Micro- vs. Macroscopic . . . .
Date: 7 Jan 1993 22:08:27 GMT
Organization: California Institute of Technology, Pasadena
NNTP-Posting-Host: torment.ugcs.caltech.edu

<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.

When you try and figure out what a "free particle" should mean in quantum
mechanics, part of the input to be given is an irreducible projective
representation of the group of rotations of 3-space. (You can ignore all
that except which group is involved.) It turns out there's one for each
dimension N. Let j=(N-1)/2. 

The irreducibility means that the space is all mixed up by the rotations:
if we restrict to only allowing rotations about a particular axis, this
is no longer true (we can't mix as much). The space breaks up into N=2j+1
pieces, now each a representation of the group of rotations about one
axis. The representations one gets are naturally labeled by the numbers
-j, -j+1, -j+2, ..., j-1, j. (These may be half-integers, in which case
one is dealing with a fermion. The fact that they can't be any more
non-integral than half-integral is a fundamental property of the group
of rotations of 3-space that I won't explain here.)

If you then ask "What's the angular momentum observable for this particle?"
(this really being your original question), you find that it's the
sum of two terms. The first is the one you're used to from classical
mechanics. The second one has to do with which of the subreps (that
list -j, -j+1, ...,j) the particle is in.

But they really are both angular momentum, although they arise very
differently. For instance, if you shine a beam of right-handed electrons
into a block of wood, it will begin to spin in a right-handed sense
(total angular momentum being conserved).

I've probably gotten some of this wrong, in which case the pleasant article
to read is by George Mackey, in "Group theory in Physics and Mathematical
Physics", edited by Moshe Flato and Gregg Zuckerman.		Allen K.

Newsgroups: sci.physics
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: sci.physics.research: research-level only?
Organization: University of Virginia
Date: Sat, 9 Jan 1993 18:41:12 GMT

In article <1993Jan9.163055.8210@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
>In article <24790@galaxy.ucr.edu> baez@guitar.ucr.edu (john baez) writes:
>>
>>I too think that sci.physics.moderated would be a better name for what
>>I'm after, but somehow when I came back from Christmas break sci.physics.research
>>is what it was called.
>
>Now that the moderators have stated their platforms, the prospect of
>simply making sci.physics into a moderated group seems a whole lot less
>threatening than it did at first.
>
>A straw poll: taking the promised platforms at their face value, just
>how many people here would feel that their rights were being
>unacceptably trampled if sci.physics was simply turned into a moderated
>group?
>
>No sense giving up a nice monicker like sci.physics if it turns out
>that this will benefit only a miniscule minority.

     I hate to belabor this point, but this is not a proposal to 
     turn sci.physics into a moderated newsgroup.  It is a formal 
     proposal to create a *new* newsgroup with a different charter
     and a different purpose.  The formal newsgroup creation process
     has been followed by Matt down to the discussion stage, which
     we are still in.  

     However, sci.physics will still exist in all its wondrous glory.

     Consideration of moderating sci.physics would be separate,
     and I suspect that the support for such a move is minimal to 
     nonexistent (and you'd have to find some moderators).  
     I know that I, for one, do not want to have sci.physics moderated.


                          dale bass
-- 
C. R. Bass                                          crb7q@virginia.edu        
Department of Mechanical, 
     Aerospace and Nuclear Engineering
University of Virginia                              (804) 924-7926
From: weemba@sagi.wistar.upenn.edu (Matthew P Wiener)
Newsgroups: sci.physics
Subject: Re: Sarfatti Forteana
Date: 4 Jan 93 20:39:47 GMT
Reply-To: weemba@sagi.wistar.upenn.edu (Matthew P Wiener)
Organization: The Wistar Institute of Anatomy and Biology
In-reply-to: jbm@hal.trl.OZ.AU (Jacques Guy)

In article <1992Dec30.223943.3346@trl.oz.au>, jbm@hal (Jacques Guy) writes:
>If that is indeed the true etymology of "Tsarfat", it would be the only
>case I know of (and I'm into comparative linguistics) where a word has
>been borrowed backwards.

Oh come on.  Within physics (ha! hahaha! physics in sci.physics!) there
is a very famous example.  Ohm (German) became mho (English and ??), the
pre-SI unit of conductance.
-- 
-Matthew P Wiener (weemba@sagi.wistar.upenn.edu)
Newsgroups: sci.physics,sci.math
From: siegman@EE.Stanford.EDU (Anthony E. Siegman)
Subject: Ansatz (as used in mathematical physics)
Organization: Stanford University
Date: Mon, 11 Jan 93 02:51:32 GMT

   I've seen the term Ansatz used (in English) to describe the
mathematical structure that is set up to analyse a physics problem or
solve a mathematical physics problem; but none of several English
dictionaries I've check contain this term, nor do my Deutsch-English
dictionaries give much clue to this usage.  Can anyone quote any
authoritative references on this particular usage?
From: Van@cup.portal.com (Sylvan Van Jacques)
Newsgroups: sci.physics
Subject: Re: infinite universe
Date: Mon, 11 Jan 93 07:28:06 PST
Organization: The Portal System (TM)
Distribution: world

 A question related to the previous posts:
 
 When astrophysicists speak of open and closed universes, do they mean that
 
 1) The spatial part of the metric has open or closed form? i.e. the universe 
has infinite or finite spatial volume?
 OR
 2) That the universe may have either an open or closed metric, but the 
density of matter is such that the expansion will
 a) keep on forever,  or
 b) stop and start contracting.
 
  I suspect that these 2 are related. Are they?
 
 When people talk about the missing matter and dark matter, and whether there 
is enough matter to close the universe, do they mean the universe is closed in 
the sense that its metric is closed? Or do they mean that the expansion will 
reverse itself. 
 Or do these two things always go together?
 
 I was taught that open and closed referred to the spatial part of the metric, 
not to the expansion of the universe.
 It seems inappropriate to speak about the density of matter determining 
whether the universe in closed or open, unless it determines whether the 
spatial part of the metric is open (hyperbolic), or closed (spherical), rather 
than determining whether or not the expansion will continue forever, or stop 
and reverse itself.
 
 Can we have a universe that has an open spatial metric, but an expansion that 
will reverse itself?
 Can we have a universe that has a closed spatial metric (and thus a finite 
spatial volume), but will keep on expanding forever?
 
 Or do Einstein's eqns. say that this is not possible? Does reversal of the 
expansion mean that the metric is closed, and if the expansion is not reversed,
 
does this mean that the metric is open?
 
 Do the terms "open and closed" mean the same in astronomy as they do in 
general relativity?
 
 Am I making sense? I have had a very hard time getting any response to this 
question, which seems quite clear to me.
 
 Van     van@cup.portal.com
Newsgroups: sci.physics
From: u108502@beta.lanl.gov (Andrew Poutiatine)
Subject: Re: Different kinds of fluids (was: bird in plane)
Organization: Los Alamos National Laboratory
Date: Fri, 8 Jan 1993 18:13:26 GMT

In article <1ijj5jINNiq2@nz12.rz.uni-karlsruhe.de> ig25@rz.uni-karlsruhe.de writes:
>In article <1992Dec7.155530.9637@newshost.lanl.gov> u108502@beta.lanl.gov (Andrew Poutiatine) writes:
>
>>Air is in act a fluid,
>
>Yes.
>
>>and at atmospheric conditions it behaves very similarly to an
>>ideal fluid.
>
>What's that?
>
>>RW Fox and AT McDonald define a fluid in the book _Introduction
>>to Fluid Mechanics_ as "a substance that deforms continuously under the 
>>application of a shear (tangential) stress no matter hOW small the shear stress
>>may be." 
>
>Again, correct.
>
>> In fact that is the definition of a Newtonian Fluid.
>
>No.  A Newtonian fluid has the additional property that shear stress and
>rate of deformation are proportional.  The rate of proportionality is
>the viscosity. 

Yes, you are correct in fact, point taken.  This is why the definition of 
dynamic viscosity, mu, is givin by Newton's law of viscosity:

		Tauxy = mu* du/dy.

It is important to note (since we seem to be picking nits) that there are two
commonly used viscosities in Newtonian fluid mechanics (and there are other
vicosities, but they are more obscure). They are the dynamic (as above) and
the kinematic, given as the ratio of the dynamic viscosity to the density.
The dynamic viscosity is often referred to as the absolute viscosity, since
it rears its head in the Navier-Stokes equation (along with a bulk viscosity
that includes the second viscosity coefficient, but this is usually 
not used  and negligible).

An ideal fluid is defined in Fox and McDonald as a fluid that is both
incompressible and inviscid, and Potter and Foss define it as a fluid that is 
inviscid.  In the latter sense an ideal gas is an ideal fluid that obeys
the ideal gas law (you can look that one up).  As we all know (I hope), 
ideal fluids are only idealizations, and hence not physical in the real world
sense.  They are useful though, since they behave in much simpler ways than
nonideal fluids, and hence are more easily treated, and often real world
fluids behave very similarly to ideal fluids in certain situations.
 
In any event, you are right, and I should not have stated what I did as 
a definition, only as a property.

-AIP
 
Newsgroups: sci.physics
From: sschaff@roc.SLAC.Stanford.EDU (Stephen F. Schaffner)
Subject: Re: lists of (un-)observed reactions?
Organization: Stanford Linear Accelerator Center
Date: Wed, 13 Jan 1993 01:08:08 GMT

In article <C0rKL4.46.1@cs.cmu.edu>, valdes+@CS.CMU.EDU (Raul Valdes-Perez) writes:
|> Can someone tell me where to find a list (preferably on-line)
|> of all the elementary-particle reactions that have been observed,
|> plus those that have never been?  Failing that, could someone
|> estimate the number of reactions in each case?
|> 

The Review of Particle Properties, put together by the Particle Data Group, 
contains pretty much everything you could want to know about particle decays.  
The latest edition appeared as Physical Review D 45 (June 1, 1992).  The 
summary tables sound like what you want (probably more than you want, in 
fact).  
	The same information is available from SLAC via e-mail.  For 
information, send the one-line mail message (with blank subject line) 
EXPLAIN PARTICLES (IN PARTICLES (note: no closing parenthesis) to 
qspires@vm.slac.stanford.edu (internet) or qspires@slacvm (bitnet); you might 
have a problem if your site hasn't been registered with SLAC.  Info can 
be obtained by sending e-mail to QSPI@SLACVM.BITNET.  There's a lot of 
information there, so you might be better off with going to a library.

-- 
Steve Schaffner        sschaff@unixhub.slac.stanford.edu
	The opinions expressed may be mine, and may not be those of SLAC, 
Stanford University, or the DOE.
Xref: sparky sci.physics:22420 alt.sci.physics.new-theories:2720 sci.skeptic:22259 alt.conspiracy:13903
Newsgroups: sci.physics,alt.sci.physics.new-theories,sci.skeptic,alt.conspiracy,alt.alien.vi
Subject: Re: Weird message - does any one know meaning?
From: jonc@status.gen.nz (Jon Clarke)
Date: Sun, 10 Jan 93 09:15:55 GMT
Organization: The Z*NET Global News Gateway in Parnell New Zealand.

sarfatti@well.sf.ca.us (Jack Sarfatti) writes:

> From: uucp@mv.MV.COM (0000-uucp(0000))
> Subject: Warning From uucp
> Apparently-To: sarfatti@well.sf.ca.us
> 
> Subject: Warning From uucp
> 
>         virgin!mail unhtel!virgin!nhstrat!rlyeh!cthulhu   (Date 01/07)
> The job will be deleted in several days if the problem is not corrected.
> If you care to kill the job, execute the following command:
> 
>         uustat -kvirginN3725
> 
>         Sincerely,
>         mv!uucp
>                             .

 
 Silly question time. Why did you post to all the above news groups when 
 a single posting to news.admin or news.misc would have answered it.
 
 Assuming this message is real, it says your news(article) batch 
 "virginn3725" has not been processed at mv.com .  It is asking if
 you want to delete it else it will autodelete if you do not call
 the sysadmin at mv.com to sort it out.
 
 Look NO conspiracy at all (ah rats)
From: tao@fine.princeton.edu (Terry Tao)
Newsgroups: sci.physics
Subject: Re: TIME HAS INERTIA   -  Another of Abian's contradictions...
Keywords: Abian cannot perform logic
Date: 8 Jan 93 19:35:25 GMT
Organization: Princeton University
Originator: news@nimaster

first Abian says

In article <abian.726458073@pv343f.vincent.iastate.edu> abian@iastate.edu (Alexander Abian) writes:

>The ordinary language is the best tool which develops, sharpens and 
>polishes the human intellect.  The ordinary language is the REAL MIRACLE 
>OF CREATION. IT IS THE MECHANISM OF RATIONALITY. IT IS THE MECHANISM OF 
>REASONING.  THE ORDINARY LANGUAGE IS THE LIFE OF THE LIFE.    


But then he admits:


>What do I mean by  "impressive"  I can't define it - it is something that
>you will recognize and feel it when you encounter it !
>  
>                                  Alexander ABIAN

And he has had similar problems with words such as "security" and
"physics".  Isn't this a contradiction?  Unable to communicate properly a
word in the "mechanism of rationality"?? 


Terry
From: ric@hpspdla.spd.HP.COM (Ric Peregrino)
Date: Tue, 5 Jan 1993 20:00:00 GMT
Subject: Simple Universe Question
Organization: HP Stanford Park - Palo Alto, CA