HDTenEightyP/NetNews huggingface dataset:
From: siegman@EE.Stanford.EDU (Anthony E. Siegman)
Subject: Re: Lasers/collimated light in RGB?
Organization: Stanford University
Date: Sun, 10 Jan 93 05:54:32 GMT

>==* Beam dispersion is a function of cavity length. Short cavity lasers tend 
>to loose their coherency more quickly as the beam travels from the laser 
>source,...and long cavity lasers tend to remain tightly packed and coherent 
>over longer distances. 

   Sorry, this is not correct, or at least somewhat confuses the
point.  "Beam dispersion" (perhaps better called beam spread, or
far-field angular spread) depends primarily on the _diameter_ of the
beam as it leaves the laser, and also on the "beam quality" of the
laser, which is a measure of how close to ideal the transverse profile
of the beam is.  Angular beam spread has no _direct_ connection to
cavity length.

   True, in practice shorter laser cavities tend to have smaller
diameter output beams, hence greater angular spread, but this is not a
fundamental attribute. With appropriate mirror design, a short cavity
laser could have a larger diameter output beam, hence less angular
spread, than a longer cavity laser of the same type.



Newsgroups: sci.physics
From: merritt@macro.bu.edu (Sean Merritt)
Newsgroups: sci.physics,news.groups
Subject: Re: sci.physics.research: Are there important unresolved issues?
Date: 11 Jan 93 15:00:49 GMT
Followup-To: sci.physics
Organization: Boston University Physics Department
In-reply-to: matt@physics2.berkeley.edu's message of 10 Jan 93 06:03:25 GMT

In article <MATT.93Jan10010325@physics2.berkeley.edu> matt@physics2.berkeley.edu (Matt Austern) writes:



>   The purpose of this article is exactly what the subject line says: I'm
>   trying to find out if there are any issues that haven't been resolved
>   yet that people think are important.  (I think it's best that we do
>   this before the vote, not after...)
>
>   I don't claim that the current proposal is perfect, only that it is
>   (in my opinion) good enough, and that I couldn't think offhand of a
>   way to make it substantially better.  The question, then: do you
>   people agree with me about that, or do you think that there is
>   anything about it that's so bad that it absolutely has to be fixed
>   before they would be willing to support it?
>
>   To be more specific, I'm interesting in hearing from you if
>	   (a) There is something in the proposal as it stands that's so
>	       bad that you would consider voting against it;


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)

>	   (b) You have a specific suggestion in mind for fixing it (I'd be
>	       especially happy if you could tell me exactly how you would
>	       like the wording in the charter to be changed); and

I think the specific guidelines of how an article get's posted or
rejected needs to be finalized before we vote. I don't think "Who"
is moderating is as important as to "How" they go about the task.

I have a very simple suggestion. If a moderator thinks an article
should be posted, it gets posted, with his last name in the subject
line. It's simple, it's not a lot of extra work for the moderators
and it allows for accountability.

>	   (c) You would support the creation of the group if these changes
>	       were made.


Under the above conditions I would change my vote(which if the present
form is maintained or no rules are posted shall be NO.).


>   One specific question: I, personally, don't have any very strong
>   preference for either sci.physics.research or sci.physics.moderated.

I think sci.physics.moderated is more accurate and it allows for 
a wider defintion of content. 


-sjm


--
Sean J. Merritt		         | "Every revolt is a cry of innocence    
Dept of Physics Boston University|  and an appeal to the essence of being."
merritt@macro.bu.edu             | Albert Camus, The Rebel
Newsgroups: sci.physics
From: jaydee@seanews.akita.com (Jay Dee Pritchard)
Subject: Time/space
Organization: SEANEWS - Seattle Public Access News + Mail
Date: Fri, 8 Jan 1993 07:03:13 GMT

Time has yet to be quantitized, or really understood.
Space has a quantity that can be measured.  Maybe time
has no spatial dimension--and even though time does occur
it is more of an abstraction.  Can time be divided down
to the chronon--a fundemental unit?  

--
[] SEANEWS [] Seattle Public Access Usenet News + Mail [] +1 206 747 NEWS []
jaydee@seanews.akita.com
From: banshee@cats.ucsc.edu (Wailer at the Gates of Dawn)
Newsgroups: sci.physics
Subject: Re: SN1987A (Was: Re: Speed of neutrinos)
Date: 12 Jan 93 23:01:59 GMT
Organization: University of California, Santa Cruz
NNTP-Posting-Host: am.ucsc.edu


corleyj@helium.gas.uug.arizona.edu (Jason D Corley ) writes:
>Is there another natural event that affected the course of science more?
>Halley's Comet, perhaps.  If you subscribe to the apple-on-the-head myth
>of Isaac Newton, I suppose that would work, too.  I can't think of any others,
>right off the top of my head...SN1987a seems to be the winner.

Thats depends if you consider retrograde motion of planets to be a natural
event.  Or even the supernova observed by Tycho.
-- 
The Wailer at the Gates of Dawn              | banshee@cats.UCSC.EDU       |
Just who ARE you calling a FROOFROO Head?    |                             |
DoD#0667  "Just a friend of the beast."      | banshee@ucscb.UCSC.EDU      |
2,3,5,7,13,17,19,31,61,89,107,127,521,607....| banshee@ucscb.BITNET        |
From: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: POP! FIZZZZ... Einstein's Dreams
Organization: Whole Earth 'Lectronic Link
Date: Tue, 5 Jan 1993 02:17:54 GMT


POP! FIZZ....REVIEW
Jack Sarfatti
Editor
Vol.1 No.1 1993
#1 Einstein's Dreams by Alan Lightman from NY TIMES Book Review, Jan 3,
1993(quotes written by Dennis Overbye):
"In one dream, a woman is swept back into the past  ... huddles in a
doorway trying not to kick up dust that could alter history."
She need not have been so careful. It does not matter what she does. The
universe will be what it will be when she leaves it in future partly
because she did whatever she did in the past. It's a big globally self-
consistent loop in time.

"... time moves in a circle  ... some unhappy people, sensing they are
doomed to endless repetitions of their mistakes, fill the night with their
moans>"

It's Dante's Inferno!

"... cause and effect become disjointed: a woman's heart leaps and week
later she meets a suitor>"

How romantic! Isn't it great that retarded causality is violated in what
John Lilly calls "cosmic coincidence control".

"In the acausal world, he gushes, 'each kiss is a kiss of immediacy.'"

Play it again Sam!
Xref: sparky sci.physics:22406 news.groups:25266 sci.misc:1992
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Newsgroups: sci.physics,news.groups,sci.misc
Subject: Re: sci.physics.research: proposed panel of moderators
Date: 9 Jan 1993 21:24:19 GMT
Organization: Intel Corp., Chandler, Arizona
NNTP-Posting-Host: stealth.intel.com

In article <MATT.93Jan8104409@physics2.berkeley.edu> matt@physics.berkeley.edu writes:
>Matthew Austern                   Just keep yelling until you attract a
>(510) 644-2618                    crowd, then a constituency, a movement, a
>austern@lbl.bitnet                faction, an army!  If you don't have any
>matt@physics.berkeley.edu         solutions, become a part of the problem!

I'd just like to say that anyone who uses that signature in
postings designed to foster a moderated newsgroup is a
hypocrite of the first net.water.

				--Blair
				  "All wet."
Newsgroups: sci.physics
From: corleyj@helium.gas.uug.arizona.edu (Jason D Corley )
Newsgroups: sci.physics
Subject: SN1987A (Was: Re: Speed of neutrinos)
Date: 12 Jan 93 17:52:29 GMT
Organization: University of Arizona, Tucson

In article <MATT.93Jan11224629@physics20.berkeley.edu> matt@physics.berkeley.edu writes:
>In article <6691@pdxgate.UUCP> gbshaw@rigel.cs.pdx.edu (Bert Shaw) writes:
>
>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.
>
>(It's amazing, actually, just how much that one supernova taught us
>about particle physics!  It has also given us the most stringent
>limits in existence for the Dirac mass of the neutrino, the magnetic
>moment of the neutrino, etc.)

No kidding!  In astronomy, too.  SN1987a was the first supernova observed
with, well, this is going to sound very silly, but the first to be observed
with 1987 technology.  To put it another way-- astronomical technology
has recently started getting better and better by leaps and bounds, and
to have a supernova to use all these new toys on....wow!

Is there another natural event that affected the course of science more?
Halley's Comet, perhaps.  If you subscribe to the apple-on-the-head myth
of Isaac Newton, I suppose that would work, too.  I can't think of any others,
right off the top of my head...SN1987a seems to be the winner.

	Jason
	Not The Jason At Oxford, Ever, Ever, Ever
From: matt@physics2.berkeley.edu (Matt Austern)
Newsgroups: sci.physics
Subject: Re: How moderation would work
Date: 12 Jan 93 16:57:53
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
Reply-To: matt@physics.berkeley.edu
NNTP-Posting-Host: physics2.berkeley.edu
In-reply-to: bob@1776.COM's message of 12 Jan 93 18:50:21 GMT

In article <m720wB1w165w@1776.COM> bob@1776.COM (Robert Coe) writes:

> There's been a lot said recently to the effect that the panel of moderators
> would (or should) vote on whether to accept a particular article.  Surely 
> that would be too cumbersome and slow!  It would (IMO) make much more sense
> to allow any member of the panel to decide on any article, bouncing it to one
> or more of the others only if he didn't feel qualified to make the call.  The
> full panel would deal only with complaints that one or more of their number
> was being too lenient or too strict.

That's the intention, and for exactly the reason you give: voting on
every article would be far too cumbersome.

The way things will work is that an article will be sent to one of the
moderators at random.  That moderator can either post it or reject it.

If necessary, the moderators can ask each other (Or other people too!
The moderators aren't experts on everything, any more than anyone else
is) for advice, but the hope is that this will only rarely be
necessary.

There will also be an alias set up so that people can send mail to all
of the moderators; that's so that people who are concerned about group
moderation can discuss them.

--
Matthew Austern                   Just keep yelling until you attract a
(510) 644-2618                    crowd, then a constituency, a movement, a
austern@lbl.bitnet                faction, an army!  If you don't have any
matt@physics.berkeley.edu         solutions, become a part of the problem!
Newsgroups: sci.physics
Subject: time, Tipler, and pulsars
From: <SHOCKER@MIAMIU.BITNET>
Date: Friday, 1 Jan 1993 18:59:55 EST
Organization: Miami University - Academic Computer Service

I've been doing research lately on practical methods of time travel and I've lo
cated an article by Frank J. Tipler titled "Rotating cylinders and the possibil
ity of global causality violation", in Physical Review D from 1974. The article
 postulates that a large but finite cylinder rotating about twice a millisecond
might generate Closed Timelike Lines. I've also found sources that say a millis
econd pulsar rotating at the same speed might do the trick (John Gribbin). Any
thoughts as to whether using such a pulsar to move backwards in time is relativ
istically feasible, and what moving through a Closed Timelike Loop generated in
 this way would be like? Other technically possible methods of time travel woul
d also be appreciated.

    Gavin R. Miller
    Shocker@miamiu
From: jim@cs.UAlberta.CA (Jim Easton)
Subject: Re: TIME HAS INERTIA (A1) EXPERIMENTALLY VERIFIED 30 TIMES/DAY
Keywords: THE CRAVE FOR GAINING A FEELING OF SECURITY
Organization: University of Alberta, Edmonton, Canada
Date: Mon, 11 Jan 1993 21:51:35 GMT

abian@iastate.edu (Alexander Abian) writes:
...
>    Do you need more proof of the PREDICTABILITY AND THE EXPERIMENTAL
>VERIFIABILITY OF  (A1)  ?  If yes, JUST EXAMINE YOUR REACTION TO
>MY  PRESENT PROVOCATIVE POSTING !!! 
...
My reaction is one of hilarity.  What makes it even better is that
you seem to have convinced a number of us that you are actually 
serious.

	Jim
From: tabitha@vms.huji.ac.il
Newsgroups: sci.physics
Subject: Omega
Date: 10 Jan 93 22:50:09 GMT
Distribution: world
Organization: The Hebrew University of Jerusalem

A question from a non-physicist regarding the current thread
on omega.

What is the generally accepted range of values for
the critical density of the universe?

A related question regarding relativistic time-dilation
in a sphere with uniformly distributed matter throughout
the volume of the sphere.  As you travel along a radius
from the surface toward the center, does the dilation
increase or decrease?  How does it vary as you move in?
If the Mass of the sphere is M and the radius R, what is the
formula for relativistic time-dilation as a function of r?

Thank you muchly.

-dennis turner
tabitha@vms.huji.ac.il
tabitha@hujivms.bitnet
Newsgroups: sci.physics
From: radford@cs.toronto.edu (Radford Neal)
Subject: Re: Budding Physicist
Organization: Department of Computer Science, University of Toronto
Date: 7 Jan 93 18:54:54 GMT

In article <93007.100220STANTONK@QUCDN.QueensU.CA> Ken <STANTONK@QUCDN.QueensU.CA> writes:

>My seven year old asked me a question that left me scratching my head...
>what [is] the MAXIMUM possible temperature, according to theory?

The maximum possible temperature is -0. 

No, that's not a typo - the answer is minus zero. 

You see, at the minimum possible temperature, which is +0, the system
is always in its lowest energy state. As the temperature rises, other
states become more probable, until, at a temperature of plus infinity,
all states become equally likely. Going futher, one can sometimes
arrainge for the *higher* energy states to be more likely than the
lower energy ones, a situation described by the temperature wrapping
around to minus infinity, and then increasing further to smaller
negative numbers as you go on. At the hottest possible temperature the
system must be in its highest energy state, and is assigned a
temperature of minus zero.

This makes more sense if you define the "coldness" to be the
reciprocal of the temperature. Then a temperature of zero becomes a
coldness of infinity, logically enough. An infinite temperature gives
zero coldness, and as you go on from there, you get into negative
coldnesses, reaching a coldness of minus infinity at a temperature of
minus zero.

Negative levels of coldness cannot, however, be obtained with systems
where there are molecules zipping around. Those can only go,
asymptotically, to zero coldness, and infinite temperature, as the
molecules go faster and faster. There's no reason to think the
temperature in such systems can't get arbitrarily close to infinity
(or at least no reason simple enough for me to understand).

    Radford Neal
From: leffler@physics.ubc.ca (Steve Leffler )
Newsgroups: sci.physics
Subject: Re: sci.physics.research: Are there important unresolved issues?
Date: 11 Jan 1993 22:37:29 GMT
Organization: The University of British Columbia
Distribution: world
NNTP-Posting-Host: physics.ubc.ca

merritt@macro.bu.edu (Sean Merritt) writes:

>I have a very simple suggestion. If a moderator thinks an article
>should be posted, it gets posted, with his last name in the subject
>line. It's simple, it's not a lot of extra work for the moderators
>and it allows for accountability.

   I agree with you that it might be useful if the name of the moderator who
approved an article appeared in it somewhere.  The subject line is not the
place for this, however.  With many newsreaders, the subject line is the only
thing one sees before choosing whether or not to read an article.  As such,
space in that line is too precious to waste on the moderator's name.  Perhaps
some other header line or an initial line in the body of the article would be
more appropriate.

				     ---Steven Leffler
					leffler@physics.ubc.ca
From: mtj@babar.asd.sgi.com (Michael Jones)
Newsgroups: sci.physics
Subject: Book reference on "Super" development sought
Keywords: books fusion
Date: 12 Jan 93 19:01:27 GMT
Organization: Silicon Graphics, Inc.
NNTP-Posting-Host: babar.asd.sgi.com

What books exist about the history of development of the fusion
bomb? I've read the U.S. Government history of the DSM efforts,
but that account stopped at the end of WW-II.

Note, I'm not looking for plans to build such a device, just for
an accounting of American efforts from the names, ideas, and places
historical perspective.

Also, I have video of the two Bikini tests. Was the yield of the
two devices ever stated? The first device was in the same housing
that was used for the second (Nagasaki) war-time drop. Was the 
second one in this same housing?

-- 

Be seeing you,      mtj@sgi.com  415.390.1455  M/S 7L-590
Michael Jones       Silicon Graphics, Advanced Graphics Division
                    2011 N. Shoreline Blvd., Mtn. View, CA 94039-7311
Newsgroups: sci.physics
From: sawyer@utahep.uta.edu (Lee Sawyer)
Subject: Re: TOP in TIME
News-Software: VAX/VMS VNEWS 1.41    
Organization: University of Texas at Arlington High Energy Physics Group
Date: Mon, 11 Jan 1993 20:28:00 GMT

In article <MATT.93Jan11102448@physics2.berkeley.edu>, matt@physics.berkeley.edu writes...
>In article <11665@sun13.scri.fsu.edu> jac@ds8.scri.fsu.edu (Jim Carr) writes:
> 
>>  The person I asked about this 
>> said they were not even prepared to speculate as to whether seeing this 
>> event indicated a rate consistent with the mass around 130 GeV suggested 
>> by the CERN results.  We will probably have to wait a year to know for 
>> sure, although it sounds like the PR has started already. 
> 
>I, however, can speculate.  (What else do theorists do?)
> 
>You can't say much about "rate" from a single event, and you can't
>even say much from two or three events.  (Even assuming, that is, that
>the D0 event and both CDF events really are top.)  However, you can
>ask this question: if the top has a mass of 130 or 140 GeV, then what
>is the expected number of events that would be seen with the
>integrated luminosity that they have at Fermilab?
> 
>The answer is: considerably less than one.  The t-tbar cross section
>goes down quite steeply as the top mass increases.  There's some
>unceratinty in the cross section (perturbative QCD calculations are
>difficult), but not a factor-of-ten uncertainty.
> 
>In other words: in my opinion, it isn't terribly likely that CDF and
>D0 would be seeing very many 130 GeV top quarks.
>--
>Matthew Austern               

    Sure, which is why for a (background subtracted) rate of N+/-stats
+/-syst events in L pb-1 of luminosity, the mass is M. Then we say if
this mass in consistent or not with the LEP results. In other words, 
the other way around from the analysis you did. The LEP constraint on 
the top mass is rather broad, something like +/- 50 GeV, and the 
mean "best fit" value varies from 120 to 170 for Higgs masses from 50 
to 1000 GeV. Here is a table for the cross-section for gg->tt at
p\bar{p} CMS energy of 1.8 TeV, to one-loop QCD corrections and
with theoretical uncertainties due mainly to ignorance of the 
gluon structure function :

   M_top       Sigma
 ---------- ------------
  100 GeV     90+/-30 pb
  120 GeV     34+/-11 pb
  140 GeV     15+/- 4 pb
  160 GeV      7+/- 2 pb

This from _Review of Top Quark Phenomenology_ by B. Lampe (MPI-Munchen),
preprint MPI-Ph/92-87.

  For around 4 pb-1 of luminosity, and an overall efficiency
of around 10% (I'm guessing here) 1 or 2 events would be right at
the edge of the LEP "best fit". 

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

         Dept of Physics                          
         Univ. of Texas                            
               at Arlington
From: antennae@gn.apc.org
Newsgroups: sci.physics
Subject: RE:TIME HAS INERTIA (What to do wit
Date: 7 Jan 93 01:41:00 GMT
Nf-ID: #R:10500.726251451@jinr.dubna.su:2135243509:gn:1541700023:000:48
Nf-From: gn.UUCP!antennae    Jan  7 01:41:00 1993



now you buggers are beginning to get somewhere
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Newsgroups: sci.physics
Subject: Re: A proof that quantum mechanics is an incomplete theory
Date: 7 Jan 1993 22:32:11 GMT
Organization: Intel Corp., Chandler, Arizona
NNTP-Posting-Host: stealth.intel.com

In article <472@mtnmath.UUCP> paul@mtnmath.UUCP (Paul Budnik) writes:
>In article <1ig6pcINN32r@chnews.intel.com>, bhoughto@sedona.intel.com (Blair P. Houghton) writes:
>> But then, so is classical mechanics.
> 
>Surely you jest?

Most of the time, but not just now.

>My result
>makes it clear that quantum mechanics does not fully describe the
>experimental results that fit in that range.

If it had, 60 years ago, we'd have been wasting 60 years
making improvements to it.

>There are time delays related to the structure of the wave
>function itself that quantum mechanics does not predict.

>The ultimate significance lies in the powerful argument it provides against
>the assumption that the wave function changes instantaneously when an
>observation is made.

It's not an assumption.  It's a feature.

It reacts to the observation.  Is this not to be expected?

>This assumption is too vague to predict some results
>that can be measured experimentally and thus is probably not simply
>vague but absolutely false. If this is the case then there is an entirely
>new class of experimental phenomena that is accessible through tests
>of Bell's inequality.

Then tests of Bell's inequlity should be conducted to determine
whether these experimental phenomena are accessible, thus proving
whether this assumption is false.

>There is a space-time structure to the nonlinear
>changes in the wave function that occur when an observation is made.
>Understanding this structure could ultimately be as important as
>quantum mechanics itself.

What do you suppose is the form of this structure?

				--Blair
				  "And don't call me Surely."
Xref: sparky sci.physics:22362 news.groups:25234 sci.misc:1981
From: srihari@sam.cchem.berkeley.edu (Srihari Keshavamurthy)
Newsgroups: sci.physics,news.groups,sci.misc
Subject: knots and stat.mech.
Date: 9 Jan 1993 03:45:17 GMT
Organization: University of California, Berkeley
Distribution: world
NNTP-Posting-Host: sam.cchem.berkeley.edu
Keywords: invariant polynomials, partition functions, knots

I have a question for the experts out there. I understand that the
q-state potts model's partition function is a knot invariant. My
question is that given a say 2d lattice model, is it possible that
the corresponding partition function can always be identified with
some knot invariant? Another question is that if you are describing
a knotted system like say DNA or some such physical system then does the
indep. variable in the knot polynomial correspond to some physical
parameter? While I am at it, what is the best reference to learn
about quantum groups without a heavy emphasis on the mathematical
aspects, apart from the "Baez articles" of course :). Thanks.    
srihari
Newsgroups: sci.physics,sci.math