HDTenEightyP/NetNews huggingface dataset:
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Uncertainty Principle [T.Bollinger => LONG]
Date: 6 Sep 92 19:12:21 GMT
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: na
Reply-To: sichase@csa2.lbl.gov
NNTP-Posting-Host: 128.3.254.197
News-Software: VAX/VMS VNEWS 1.3-4   

In article <1992Sep7.001518.525@prim>, prim!dave@germany.eu.net (Dave Griffiths) writes...
> 
>Can you (hopefully without getting too technical!) explain what is meant by
>"hidden variables"? I have seen it mentioned many times, but without a
>precise definition of the class of theories it represents.

When you perform a certain measurement on an ensemble of identically prepared 
systems and find half yield value V1 for the observable V and the other
half yeild value V2, you say that each system was in a superposition of
eigenstates of V with eigenvalues V1 and V2.  The particular value Vi which 
you measure was not determined until the act of measurement forces the 
system into an eigenstate of V.  However, this sits poorly with some people,
who have speculated that there exist "hidden variables" which allow more
a more complete description of the system.  If you knew the value of the
hidden variable then you could predict whether measurement would yield
V1 or V2 for a particular system.  

Thus, in the "hidden variables" picture, QM is not a complete physical
description of systems.  There is some underlying model, of which QM
is an approximation, in which every observable is completely specified,
and there is no uncertainty as to what a given measurement will yeild.
It's just that we don't know this theory and so do not know how to 
predict correctly.  Thus, the "superposition state" which we use to 
describe QM systems represents our own ignorance of the underlying physics,
not any fundamental uncertainty in the actual value of some observable in
a given system.

>I don't think it's enough to just accept QM the way it is. It seems to have
>horrible flaws (the collapse of the wave function when "observed", whatever

The only horrible flaw which a physical theory can have is to disagree
with the observed facts.  Whether you find the implications of QM pleasing
or not, you will have to live with them because QM is an accurate description
of nature.  At least until someone develops a body of experimental evidence
in contradiction to QM, we can't possibly know how to modify it anyway.

-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
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: E=mc2?
Date: 5 Sep 92 02:38:21 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Organization: SCRI, Florida State University

In article <1992Sep4.205540.26583@u.washington.edu> mcfarlan@corona.math.washington.edu (Thomas J. McFarlane) writes:
>In article <10585@sun13.scri.fsu.edu> jac@ds8.scri.fsu.edu (Jim Carr) writes:
>
>>Thus relativistic mechanics is not at the foundation of the physics 
>>of the bomb.  Indeed, from the perspective of 1943, quantum mechanics 
>>was hardly required since the models used to make sense of the data 
>>concerning uranium fission were macroscopic ones and not true quantum 
>>mechanical calculations.  
>>
>  It's a little hard for me to swallow that QM was hardly needed.
>Was this really the case? 

Well, in the sense that we use "quantum mechanic calculation" today, it 
is.  There was no attempt to solve a many-body wave equation with pauli 
exclusion etc etc in NR QM.  Good thing, too, since it is tough to get 
decent answers today. 

The original calculations treated the nucleus as a liquid drop as a 
model for understanding the fission process.  The calculations of the 
reaction rates treated the neutrons as a diffusing gas with interaction 
rates taken from experiment.  You can see the exact things that were 
done in the "Los Alamos Primer", now declassified and published with 
annotations (extensive, since there was *very* little in the primer 
itself) by the author: Robert Serber. 

BTW, I looked for the Einstein letter to Roosevelt in Rhodes' book, 
and it is not there.  Rhodes does make clear that the letter from 
Einstein was not penned by Szilard, but that Szilard and Sachs 
included a cover letter that accompanied the letter by Einstein. 
I know I have seen it, but it must have been at the Oppenheimer 
Science Museum in Los Alamos. 

--
J. A. Carr                                    |  "The New Frontier of which I  
jac@gw.scri.fsu.edu                           |  speak is not a set of promises
Florida State University  B-186               |  -- it is a set of challenges."
Supercomputer Computations Research Institute |   John F. Kennedy (15 July 60)
Newsgroups: sci.physics
From: hporopudas@tnclus.tele.nokia.fi
Subject: Re: Black hole + anti-Black hole = ?
Organization: Nokia Telecommunications.
Date: Mon, 14 Sep 1992 07:53:25 GMT


In article <1992Sep9.163238.1@tnclus.tele.nokia.fi>,
hporopudas@tnclus.tele.nokia.fi writes:
>
> In article <18jgmmINNm4g@smaug.West.Sun.COM>,
> Richard.Mathews@West.Sun.COM (Richard M. Mathews) writes:
>> barry@arnold.math.ucla.edu (Barry Merriman) writes:
>>>What happens if you dump some antimatter into a black
>>>hole that formed from normal matter? Does it 'cancel out' part of it?
>>
>>>Or, if I take two black holes, one made from ordinary matter
>>>and the other made from anti-matter, and merge them, what happens?
>>>Do I get a bigger black hole, or are they somehow annihilated?
>>
>> The "classical" theory of General Relativity predicts that black holes
>> are described only by 3 numbers: mass, spin, and electric charge.  Black
>> holes do not have a lepton number or a baryon number.  A black hole
>> created from ordinary matter is indistinguishable from a black hole
>> created from anti-matter.  Thus black_hole + anti_black_hole is the
>> same as black_hole + black_hole; the quantity
>> 	(M + sqrt(M^2 - Q^2 - S^2/M^2))^2 + S^2/M^2
>> summed over all black holes is guaranteed to be non-decreasing.
>>
>> Now, it bothers me that Hawking evaporation does not conserve lepton and
>> baryon number.  Something related to gravity just shouldn't be fooling
>> with such things.  Personally, I think that a TOE will get rid of the
>> singularity at the center of a black hole (assuming it doesn't get rid
>> of black holes completely), and it will replace the singularity with
>> something which does conserve lepton and baryon number.  That would
>> mean that black holes would have lepton and baryon numbers, though you
>> might not be able to directly measure those until the hole evaporates
>> away.
>>
>>      Richard M. Mathews			Lietuva laisva = Free Lithuania
>> 					Brivu Latviju  = Free Latvia
>> Richard.Mathews@West.Sun.COM		Eesti vabaks   = Free Estonia
>> 					        WE  DID  IT!!!
>
>  What if we combine two black holes such that one is from contracting
>  universe and one from expanding universe. ?
>  These two have different signs of masses. First mass is negative and second
>  mass is positive.
>
>              Hannu.
>
>
>

     I must take my words, that I said above, back.

     I'am not sure at the moment that should there exist black holes in
   contracting universe. This depends on what kind of metrics should describe
   spherically (or some other surface) symmetric negative mass distribution.
     If Schwartscild metrics could be used, then there possibly does not exist
   black-holes (no singularity) in contracting universe.
     I remain this question open at the moment.

            G M
       1 -  ----    is not zero if M is negative (no singularity exists ?).
               2
            r c


           Hannu.
From: carlip@landau.ucdavis.edu (Steve Carlip)
Newsgroups: sci.physics
Subject: Re: Did electric/magnetic symmetry "break"?
Date: 6 Sep 92 00:57:32 GMT
Organization: Physics, UC Davis

In article <5SEP199219330991@zeus.tamu.edu> dwr2560@zeus.tamu.edu (RING, DAVID WAYNE) writes:

[stuff deleted about duality symmetry in electromagnetism]
 
>'rotate' and 'direction' suggest a continuous symmetry. But taking the dual
>is discrete. Is that right?

Taking the dual is discrete, but there is a continuous U(1) symmetry of
the source-free Maxwell equations, with 
F --> F cos a + *F sin a
*F --> *F cos a - F sin a
(up to possible constants --- I never know how to normalize a Hodge
dual).  There's a reasonably good discussion of this in Jackson,
section 6.12.

Steve Carlip
carlip@dirac.ucdavis.edu
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Abusing the laws of physics
Date: 14 Sep 92 02:21:02 GMT
 <1992Sep9.233925.29001@leland.Stanford.EDU> <9225806.13146@mulga.cs.mu.OZ.AU>

fjh@munta.cs.mu.OZ.AU (Fergus James HENDERSON) writes:

>underdog@leland.Stanford.EDU (Dwight Joe) writes:

>>For the curious, I'll show that certain forms of afterlife are absolutely
>>impossible. [...argument from thermodynamics...heat death precludes
infinite reincarnation...] 
>>At some point, eons from now, everything will be dead.

Not necessarily... the fraction of useable energy may decrease, but
that doesn't mean it has to go to zero.  I believe Freeman Dyson has
argued that it may be possible to carry on some sort of conscious
existence even in a universe that grinds irreversibly toward heat
death; the key is to use less and less energy at lower and lower
temperatures as time goes by.  Nothing like our current biology would
survive, of course, but given that some form of intelligent life could
survive all the other perils of existence and stick around several
billion years from now, that doesn't seem like much of an obstacle.

>You might be able to make a reasonable case by appealing to the Big Bang 
>Theory, but that's only a "theory", so I guess it's not as persuasive as being
>able to appeal to a "law".

In physics there are only theories and empirical data.  Laws are just
theories with lots of data to support them.  In any case, the Big Bang
theory says nothing about heat death; if there's enough matter, the
universe could recollapse before anything like that happens.  Of
course, then its history *would* be finite.  
-- 
Matt McIrvin, Cambridge, Massachusetts, USA 
Newsgroups: sci.physics
From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
Subject: Re: Question about falling elevator...
Organization: Computer Science Department,  Stanford University.
Date: Fri, 11 Sep 1992 21:25:49 GMT

In article <88580@netnews.upenn.edu> owens@hilbert.wharton.upenn.edu (Susan Owens) writes:
>
>  I have a question that I thought maybe someone here could answer.  It
>concerns a falling elevator.  If I was in an elevator that was falling
>say 20 stories what would happen if I jumped right before I hit the
>ground.

Your best bet is to press your head firmly against the floor.  Here's
why.

At the bottom of at least some elevator shafts, hopefully yours, is a
hefty spring, allowing the elevator to decelerate at the bottom with a
much more modest G-force than without it.  Your head will decelerate at
the same rate as the elevator while it remains on the floor.  If you
try and hold it above the floor it will miss the "deceleration window"
and will come smashing down on the floor about when the elevator has
come to a complete halt, where it will suffer a far greater G-force
than the elevator did.

Assuming your head can tolerate being squished out of shape by an inch,
I reckon this strategy ought to reduce the deceleration of your head at
impact by a factor of between ten and a hundred.  If your head can only
tolerate a tenth of an inch of squishing then this strategy is worth an
additional factor of ten (acceleration = velocity^2/distance).

If you jump you just further put off the evil moment when your head
reaches the floor.  By that time the elevator should be bouncing back
up, so you'll hit the floor harder still.

The rest of your body should be pressed to the floor as well.  But
*especially* your head, if that survives the impact the rest of you
probably will too.

This leaves the question of how to press your head against the floor
while in free fall.  With luck the fall won't be completely free.

All very hypothetical.  Like planning for nuclear war.

-- 
======================================================| God found the positive
Vaughan Pratt   pratt@cs.Stanford.EDU   415-494-2545  | integers, zero was
======================================================| there when He arrived.
From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
Subject: Re: Elevator mayhem
Organization: Computer Science Department,  Stanford University.
Date: Tue, 15 Sep 1992 21:16:16 GMT

In article <1992Sep15.143332.6702@math.toronto.edu> hsieh@math.toronto.edu (Paul Hsieh) writes:
>Well, I've though about this once (not too seriously) and figure that if your
>timing is good enough that you could jump up at the last second before impact
>to actually reduce the speed.  Then you could end up with method 2) with 
>lesser impact.  :)  I don't know if there is any merit to what I've just said
>but I'm wondering if there is anything fundamentally flawed with it (besides
>the amazing timing that would be required).
>

There's a very simple argument showing that jumping can't help.  If you
could absorb all your kinetic energy by jumping at the right instant,
you could with the same jump from a motionless elevator jump back up to
where you started falling from (in the absence of braking and other
resistance), putting you in a league with that other famous
jumper-over-tall-buildings.  And if you could do this you would have to
be well calibrated in this Olympic event, since if you jumped exactly
twice as hard as was necessary your head would have the identical
impact at the roof of the elevator that we've been trying to avoid on
the floor.

-- 
======================================================| God found the positive
Vaughan Pratt   pratt@cs.Stanford.EDU   415-494-2545  | integers, zero was
======================================================| there when He arrived.
Newsgroups: sci.physics,sci.math,sci.logic
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Why Do Mirrors Reverse Left/Right and Not Up/Down?
Date: 6 Sep 92 18:55:49 GMT
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: na
Reply-To: sichase@csa2.lbl.gov
NNTP-Posting-Host: 128.3.254.197
News-Software: VAX/VMS VNEWS 1.3-4   

In article <18bd9dINNj8s@agate.berkeley.edu>, ted@physics.Berkeley.EDU (Emory F. Bunn) writes...
>For what it's worth, I think it would be nice if the FAQ entry on
>this subject included an explanation of the fact that the apparent
>left-right reversal in mirrors is due primarily to the fact that
>people have a high degree of left-right symmetry.  That is, that when
>you see your reflection in the mirror, you interpret the image as a person
>who has been rotated through 180 degrees about a vertical axis with 
>respect to you, which leads to the mapping left hand -> right hand,
>etc.  That is, what the last poster said was right.

I'm not sure that I agree with this sentiment.  Imagine what you would see
if the left half of your body was completely different than the right half.
Let's say the left side is purple and the right side is green.  When you
look in the mirror you see someone with a purple *right* side, regardless
of the fact that you were not bilaterally symmetric to begin with.  The
same thought experiment works no matter how badly asymmetric you are.

I think that the impression of left-right reversal depends only on the
fact that we are *not* symmetric front to back.  When you look in the mirror,
you imagine turning the person in the image around by 180 degrees so that
they are looking in the same direction as you are.  This causes the in-out
reversal of the mirror to become a left-right reversal.  And the only 
reason that you think to do this is that your front side is so different
than your back side - not that your left is so much like your right.

>Given the high quality of the FAQ overall, I'm sure that whoever
>modifies the entry will include an explanation that's much more
>lucid than the one I just gave.

Why, thank you.

-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
From: pierson@empror.enet.dec.com (dave pierson)
Newsgroups: sci.physics.fusion
Subject: Re:  Fleischmann at press conference and Frank Close remarks
Keywords: Short Wave, BBC
Date: 8 Sep 92 13:59:50 GMT
Organization: Digital Equipment Corporation


	(half asleep, i fear) I heard mention on the BBC of an interview with
	Fleischmann and "one of his critics".  This is to be broadcast "today"
	9-Sep, 4:30(?) UTC.  (23:30 EDT, USA, 8 Sep) in the Discovery show.

thanks
dave pierson			|the facts, as accurately as i can manage,
Digital Equipment Corporation	|the opinions, my own.
146 Main St			|I am the NRA.
Maynard, Mass	
01754				pierson@majsty.enet.dec.com
"He has read everything, and, to his credit, written nothing."  A J Raffles
Newsgroups: sci.physics.fusion
From: Dieter Britz <BRITZ@kemi.aau.dk>
Subject: Monthly note: How to get the archived bibliography files.
Reply-To: Dieter Britz <BRITZ@kemi.aau.dk>
Organization: Sci.physics.fusion/Mail Gateway
Date: Mon, 7 Sep 1992 02:32:14 GMT


I get asked regularly how to get the archived bibliography files. Here is how:
-----------------------------------------------------------------------------
1. By anonymous FTP from vm1.nodak.edu (134.129.111.1).  Use the userid
   anonymous and your e-mail address as the password (but 'anonymous' seems
   also to work). Once connected, enter
   cd fusion
   to access the fusion archives.  Then you may enter
   dir fusion.cnf*
   to get a listing of the bibliography files. The index is large, so this
   restriction saves a lot of time; if you should type in a global DIR, you
   can terminate the endless stream with CTRL-C, which gets you what the
   system calls an amicable abort. To transfer a given file use
   GET (ie. mget fusion.cnf*  or  get fusion.cnf-bks  etc.).
   Enter  quit to terminate ftp.

2. Via LISTSERV, which means you get it sent by email. To first find out what
   is in the archive, send an email to listserv@ndsuvm1.bitnet, with a blank
   SUBJECT line, and the "message" consisting of the command
   index fusion
   You get a largish list of all files available. To get any one of these
   files, you then send to the same address the command, e.g.,
   get fusion 91-00487
   get fusion cnf-pap1
   etc, according to what you're after.
   My files are: cnf-bks (books), cnf-pap1..cnf-pap5 (papers, slices 1..5),
   cnf-pat (patents), cnf-cmnt (comments), cnf-peri (peripherals),
   cnf-unp (unpublished stuff collected by Vince Cate, hydrogen/metal
   references from Terry Bollinger). There is also the file cnf-brif, which
   has all the references of the -pap* files but without annotations, all in
   one file.
------------------------------------------------------------------------------

Note: It appears that you can GET only 512 kb on any one day, so it might take
you a couple of days to get the whole pap file; each cnf-pap slice is about
150 kb long.
                                                                      Dieter
------------------------------------------------------------------------------
Dieter Britz alias britz@kemi.aau.dk
Kemisk Institut, Aarhus Universitet, 8000 Aarhus C, Denmark.
==============================================================================
From: tomk@netcom.com (Thomas H. Kunich)
Subject: Re: Ball lightning
Date: Sat, 12 Sep 92 00:02:26 GMT
Organization: Netcom - Online Communication Services (408 241-9760 guest)

In article <1992Sep11.201832.10453@prometheus.UUCP> pmk@prometheus.UUCP (Paul M. Koloc) writes:
>
>> .   .          .   . .   Occasionally the balls move against the
>>direction of the prevailing winds  .. .
>
>Usually not.  However when they are coupled magnetically to nearby
>iron (ferrite in the soil), current in conductors or repelled by 
>generating image currents in nearby conducting sheets, they can move
>adversely to air currents.  For example, through image currents a
>BL within an Eastern Airlines passenger jet tracked straight along
>the center isle and plane's metal skin axis.  This BL was bluish.
>
>> .. ... and penetrate window panes without making
>>a hole in the glass (which was also observed in lab experiments). 
>
>BL would burn a hole through solid media.  RF plasmas do not.  A 

Around 1965 I was present at the debriefing of a B-52 crew
who realted the following story:

While flying at normal cruising altitude (I forget what that is,
but it's pretty high) and at cruising speed (again I forget but would
estimate above 400 knots) a ball lightning passed the aircraft off
the starboard side. It then slowed up and the aircraft repassed
the BL. Shortly thereafter the BL passed the aircraft on the port
side. It then slowed up and the aircraft repassed it again. After
that it repassed the aircraft on the starboard side again, pulled in front
of the aircraft and slowed abruptly. As the aircraft approached the 
air currents carried the BL below the nose of the aircraft where it struck
and exploded with a loud bang and flash.

I inspected the nose of the B-52 and  there was a mark on the nose
radome of the B-52. It was shaped almost exactly like the comic book
version of a lightning bolt and must have been about 3-4 feet  long
(working from memory again). It was almost exactly down the center 
of the aircraft axis. It started a foot or so from the front-most
section of the radome and was situated along the longitudinal axis
of the aircraft.

I would have suspected one of the many jokes the crews would play except
for one thing: the mark was _inside_ of the fiberglass layup. There
was _no_ exterior hole. The fiberglass radome was white but the outer
layers were translucent and you could see the shape inside between the
layers. There was no mark visable on the interior of the radome.
However, the inside layers were opaque.

The shape was slightly fuzzy and was dark gray or black. Since the
shape was inside a white translucent layup it was difficult to tell
much about it. But it was there, and the BL moved faster than the B-52 at
high altitude and it passed inside the insulating radome without
leaving a hole of any kind that was noticeable.

Newsgroups: sci.physics.fusion