HDTenEightyP/NetNews huggingface dataset:
From: Paul.Ciszek@mailbox.bison.mb.ca (Paul Ciszek)
Newsgroups: sci.physics
Subject: black holes & baryon number
Date: 5 Oct 92 09:45:22 GMT

Organization: University of Denver, Dept. of Math & Comp. Sci.

Could someone please clear up the following for me?

Suppose we start with a cloud of hydrogen, with a total baryon number
equal to the number of hydrogen atoms present.  As this cloud goes from
protosun -> star -> supernovae -> neutron star, baryon number is conserved.
Fine and dandy.  Now the neutron star collapses into a black hole.  I guess
I ought to assume the black hole still "remembers" the baryon number somehow.
Now, according to Hawking, the black hole evaporates into "radiation".
Does it "evaporate" into light?  Or did he mean "particle radiation"?
Is baryon number conserved in this last stage?

--
Paul Ciszek, pciszek@nyx.cs.du.edu | No nation was ever drunk when wine was
                                   | cheap.   -- Thomas Jefferson

 * Origin: The Electronic Mailbox (1:348/7.0)
Newsgroups: sci.physics
From: bhv@areaplg2.corp.mot.com (Bronis Vidugiris)
Subject: Re: Defining local, causal etc., was: Hidden variable theories
Organization: Motorola, CCR&D, CORP, Schaumburg, IL
Date: Mon, 28 Sep 1992 20:25:08 GMT

In article <1992Sep25.184834.13257@newshost.lanl.gov> jlg@cochiti.lanl.gov (Jim Giles) writes:
)In article <1992Sep23.153640.4394@sei.cmu.edu>, firth@sei.cmu.edu
)(Robert Firth) writes:
)
)|>  [...]                                                 maybe it is
)|> best if I try to set out my own position as clearly as possible,
)|> and that position is that the "instantaneous collapse of the wave
)|> function" is well defined within quantum mechanics, and its meaning
)|> is clear from the formalism.
)
)The fact that something is well defined or has meaning *within*
)a formal system does not imply that is has *physical* reality.
)Only consequences which can be independently verified can demonstrate
)the reality of anything.  It is not empirically possible to 
)distinguish between "wavefunctions are *real* and collapse" and
)the statement "wavefunctions are mathematical abstractions from
)which distributions can be calculated".

But it is possible to distinguish between theories where wavefunctions
are hypothetical entities that collapse 'at the speed of light' (aka 'in a
lorentz invariant manner), and wavefunctions are hypothetical entities that
collapse 'instantaneously' - or some of the other equivalent alternatives
that may not involve collapse.

Von Neuman (sp?) was wrong about all collapse theories being equivalent, as
Bell has shown.
Xref: sparky sci.physics:15702 sci.astro:10272 sci.math:12515 sci.philosophy.tech:3502
From: sichase@csa1.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics,sci.astro,sci.math,sci.philosophy.tech
Subject: Re: STRUCTURE OF TIME
Date: 30 Sep 1992 10:45 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 <1992Sep29.232349.3991@leland.Stanford.EDU>, ledwards@leland.Stanford.EDU (Laurence James Edwards) writes...
> 
>small language hint:
> 
>"Mads so," "Mads," and "Wises" are not english words or phrases.

If he ever wises up, he'll be a better man for it.

-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: Boris.Shteinbock@mailbox.bison.mb.ca (Boris Shteinbock)
Newsgroups: sci.physics
Subject: Understand...!!!!
Date: 24 Sep 92 23:21:30 CST

Organization: The University of Calgary, Alberta

I would like to start a discussion related to an understanding of the
Universe

Strange thing. We talk about physics using all this different words
and phrases like mass, energy, time, particle, wave ,field, etc.
but this words don't make any sense if you'll look more carefully


What is Energy ?

What is time ?

What is field ?

What is ... ?


Send all flames to /dev/null please

-------------------------------------------------------------------
Mathematics knows everything about an imaginary world
Physics knows nothing about real one
------------------------------------------------------------------- 

 * Origin: The Electronic Mailbox (1:348/7.0)

Newsgroups: sci.physics
From: prim!dave@germany.eu.net (Dave Griffiths)
Subject: Question about electron spin
Organization: Primitive Software Ltd.
Date: Sun, 27 Sep 1992 18:55:39 GMT

I've just been reading Roger Penrose's explanation in the Emperor's New Mind
of the EPR experiment. In this he claims that it is possible to measure the
spin of an electron in three different directions at 120 degrees to each
other and obtain the result YES, the spin of the electron is aligned in
that direction for each measurement. Surely this is incorrect? He has already
shown that if you measure the spin in one direction and get the answer YES,
then there is a probability of (1 + cos 120)/2 = 1/4 that a measurement at
120 degrees to this will also give the answer YES. Fine. But surely, with 
the wave function having collapsed, it's not possible for three measurements 
at 120 degrees to each other _all_ to give YES?

If it is possible, has such a result ever been experimentally confirmed?

Please say no.

Dave Griffiths
Newsgroups: sci.physics,sci.math
From: msb@sq.sq.com (Mark Brader)
Subject: Re: How do you draw a straight line?
Organization: SoftQuad Inc., Toronto, Canada
Date: Tue, 6 Oct 92 20:13:06 GMT

> How about pulling a piece of string taut?  Won't that give a straight line?

	"There is no force, however great,
	 can stretch a cord, however fine,
	 into a horizontal line
	 that is accurately straight."

Well, I couldn't resist.  The above is an unintentional poem that someone
found in a textbook a few decades ago, after which it eventually found its
way into Martin Gardner's column.  I don't remember the specifics.  I do
remember that the author was not amused, and changed the wording in the
next edition of the textbook.

A folded piece of paper can make a decent straightedge, though this is
obviously not a practical solution for longer distances, or if a high
degree of accuracy is required.
-- 
Mark Brader 		"Oh, especially if it's accurate. There's nothing worse
utzoo!sq!msb		 than *accurate*, ill-informed, irresponsible press
msb@sq.com		 speculation."  -- Sir Humphrey ("Yes, Prime Minister")

This article is in the public domain.
Newsgroups: sci.physics
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Subject: Re: What is the Speed of Gravity - A Call for a Volunteer
Organization: National University of Singapore
Date: Thu, 1 Oct 1992 02:06:51 GMT

sichase@csa1.lbl.gov (SCOTT I CHASE) writes:
: OK.  I think it's time that this question appear in the FAQ.  But I'm 
: not the right man to do the job.  Would one of the experts please volunteer?
: Send E-mail if you're interested (or even just willing).  Don't make me
: write this one myself.  You'll be sorry.
: 
: -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

I hope that the eventual entry will discuss what happens when the
gravitational waves are propagating in a background which is not
approximately flat. Does "gravity" propagate at the speed of light near
a black hole?
From: brahm@cco.caltech.edu (David E. Brahm)
Newsgroups: sci.physics
Subject: Re: Feynmann diagrams
Summary: FeynArts, FeynCalc for Mathematica
Date: 3 Oct 92 06:29:47 GMT
Organization: California Institute of Technology, Pasadena
NNTP-Posting-Host: punisher.caltech.edu

rmz@ifi.uio.no (Bj|rn Remseth) writes:
> Are there any computer programs  for drawing and manipulating Feynmann
> diagrams?

I just acquired FeynArts and FeynCalc by anonymous ftp to 131.225.10.4, in
directory pub.  These are packages for Mathematica 2.1; the former
constructs Feynman diagrams, and the latter calculates them.  I haven't
gotten to try them yet, but I'm told they're great, sure to be a big hit
with the kids this Christmas!

--
Staccato signals of constant information,  |  David Brahm, physicist
A loose affiliation of millionaires and    |  (brahm@cco.caltech.edu)
  billionaires and Baby ...                |---- Carpe Post Meridiem! --
These are the days of miracle and wonder,  | Disclaimer:  I only speak
And don't cry, Baby, don't cry, don't cry. | for the sensible folks.
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Newsgroups: sci.physics
Subject: Re: Quantum Nights 1
Date: 1 Oct 92 23:33:47 GMT
Organization: Intel Corp., Chandler, Arizona

In article <BvFCpL.Atx@well.sf.ca.us> sarfatti@well.sf.ca.us (Jack Sarfatti) writes:
>Night Thoughts of a Quantum Mechanic in the style of Ludwig Wittgenstein. 1
>
>An electric charge is freely falling. A photon detector is freely falling.

Okayyyy...

>The freely falling detector will not detect real photons from the freely
>falling charge.

Sez who?

				--Blair
				  "In the style of Squiggy."
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: BAEZIAN physics and astronomy [was: Space-time IS a semi-Riemannian manifold (?)
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Tue, 6 Oct 92 02:52:21 GMT

In article <1992Oct5.125835.15091@sei.cmu.edu> firth@sei.cmu.edu (Robert Firth) writes:
>In article <1992Oct5.091234.29484@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:
>
>>So naturally what I meant was that CLASSICAL spacetime IS a
>>semi-riemannian manifold.
>
>... and later ...
>
>>Spacetime is the set of all events.
>
>Now I'm *really* confused!  Which of the above mutually contradictory
>views do you in fact hold?

I must have drunk too much at the reception 'cause I'm going to try to
stick up for McInnes B T (Dr).  He is not contradictory if he assumes
that spacetime is a semi-Riemannian manifold, hence a set of point, and
if he assumes that each point is, or designates, an event.  The latter
is pretty standard GR rhetoric, but don't ask me what an "event" is or
I'll just say "a point in spacetime."  :-)

By the way, I love the subject line except for that extra "Z" which I am
assiduously deleting.  
Newsgroups: sci.physics
From: tolman%mindblow.cs.utah.edu@cs.utah.edu (Kenneth Tolman)
Subject: Make time stop?
Date: 29 Sep 92 17:10:40 MDT
Organization: University of Utah, CompSci Dept

  A frame of reference moving very very fast has a time dilation, correct?
(That is, if we are still and looking at someone moving they are "slow")
When we look out into the universe- all galaxies are moving away from us,
and the very far away galaxies are moving near the speed of light.

Therefore, THEIR TIME HAS BARELY BEGUN.  Their civilization's have not 
started, and they live in a "young" universe.  Thus, if we could travel
faster than light, we could jump backwards and live this whole universe
through once again.  Of course, the converse is true just as well from
their perspective.  Is this analysis somewhat correct?


Newsgroups: sci.physics
From: elada@eos.ncsu.edu (ERIC  LADA)
Subject: elem. questiona about ST o. Relaticity
Originator: elada@c00175-100lez.eos.ncsu.edu
Reply-To: elada@eos.ncsu.edu (ERIC  LADA)
Organization: North Carolina State University, Project Eos
Date: Tue, 6 Oct 1992 05:42:17 GMT


	Please pardon my specific ignorance and general stupidity on all things.
But I an haveing some problems understanding the special theory of relartivity.
Could some nice kind person help me out, and answer a few questions I am haveing
with the theory.

one:  Let's say U have a skater(Mod Bob) rapidly advancing toward a cluster of 
	unsuspecting old ladies(victims) who are standing around waiting 2 Cross
	the street.  Because the skater is moving w.  respect to the old ladies,
	time will slow down for the sk8er w. respect to the old ladies.  So if 
	the old  were to suddenly look up at the skaters watch they would notice
	that the hands were moving a little slowely.  Right? I think I kinda 
	understand that part. 

	But,  What about the sk8er.  As he/she(though I've never seen a female
	sk8er, and certainly not 1 named Bob), c's the world, the old ladies are
	raopidly advanceing toward her/him.  So time should slow down for the 
	old ladies.  How then can both frames of referece be valid?


And here's another question about frams-o-reference:	

	Nothing can travel faster than the speed of light whithout turning into 
energy or going sdrawkcab(that's backwards speled sdrawkcab) in time(or some 
other hocus-pocus like that) (right? I hope?)   Well Everythings relative(right?)
so if Big Bird is shot out of a cannon at 299,984 m/s and the Cookie-moster is 
joggingt in the opposite direction(trying 2 get rid of some of those fattening 
cookies) going only 15 m/s, then as Big Bird sees it, the Cookie-monstor is 
jogging at a whopping speed of 299,999 m/s. No problem.  But if the cooke 
Were to throw one of his cookies forward, at 4m/s, the cooke would be going 
faster that the speed-o-lite(as Big Bird sees it) How can that be or is it, or 
somethin

Thank you, thank you
/s

	
Newsgroups: sci.physics
From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
Subject: Re: Understand...!!!!
Organization: Computer Science Department,  Stanford University.
Date: Wed, 30 Sep 1992 14:55:51 GMT

In article <1992Sep30.120309.9782@sei.cmu.edu> firth@sei.cmu.edu (Robert Firth) writes:
>In article <1992Sep30.073018.13232@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:
>
>>I am holding in my hand a baloney sandwich. I hereby declare that this
>>is an instance of a clock. Now I note that as the baloney sandwich
>>decreases, so does my hunger. Since time is what a clock measures, I
>>deduce that: Time is hunger.
>
>An interesting clock.  And you're right: numerous experiments have
>shown that psychological time is closely correlated with metabolic
>rate.  If you shut people up in caves, for instance, their circadien
>rhythm will drift, and after a week or so they will indeed start
>measuring time in terms of hunger, or fatigue.

1. How do these arguments distinguish time from space?  People talk in
terms of "an hour's drive away," and "five car-lengths".  These
properties you attribute to time would seem to apply to just about any
commonly perceived variable.

2. The velocity of light is exactly 299792458 m/sec (an integer, God
must exist after all).  Is it still an integer when time is measured in
meters per baloney sandwich consumed by Matt?  How can you even be sure
that Matt consumes at a rational speed?

-- 
=================================================== In short, I am floundering
Vaughan Pratt   pratt@cs.Stanford.EDU  415-494-2545 around and don't take what
=================================================== I say seriously.
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Can Information Have Physical Units?
Date: 6 Oct 1992 14:54 PST
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: world
NNTP-Posting-Host: 128.3.254.197
News-Software: VAX/VMS VNEWS 1.41    

In article <1992Oct6.170513.25273@galois.mit.edu>, jbaez@riesz.mit.edu (John C. Baez) writes...

>"bits".  If we use natural log, as Boltzmann did, this number is the
>number of "nits".  Wasting energy arguing over small pieces of
>information is therefore known as "nitpicking."

You've got to be kidding.  I hope you were kidding.  A nit is the egg of a
louse, or, sometimes, its young.  Nit picking was a normal grooming activity
until quite recently, and required someone to painstakingly search through
your hair, looking for these tiny objects on or near your scalp.  It is 
remembered today mostly for the need to invest a large amount of effort
on something which seems, on the surface, too small to care about.


--------------------
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: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Newsgroups: sci.physics
Subject: Re: FTL Experiment (really a metacommentary on reposting)
Date: 29 Sep 92 04:02:46 GMT
Organization: University of Virginia

In article <717712154.109@mailbox.bison.mb> Bronis.Vidugiris@mailbox.bison.mb.ca (Bronis Vidugiris) writes:
(actually he wrote it a while back)

   It only took me about 10 articles before I realized that 
   Mr. mailbox.bison.mb.ca was having some sort of reposting
   problem (fidonet site perhaps?).  

   Though it seems good for the digestion, I'd really better stop
   eating teflon.  

                                  dale bass
-- 
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926
From: luther@ohstpy.mps.ohio-state.edu
Newsgroups: sci.physics
Subject: Re: Question about electron spin
Date: 30 Sep 92 00:18:46 EDT

In article <10919@sun13.scri.fsu.edu>, jac@ds8.scri.fsu.edu (Jim Carr) writes:
> In article <1992Sep28.174343.714@prim> prim!dave@germany.eu.net (Dave Griffiths) writes:
>>
>>No wonder they call it spin. :-) Seems the notion of spin in a particular
>>direction is a bit meaningless if you can detect it in all three
> 
>>>Is your brain numb yet? 
>>
>>Yes.
> 
> Then you are off to a good start.  I recommend that you think about 
> the problem with polaroids, and do a few experiments with them.  It 
> is a very good way to learn about the ideas of state vectors.  (I 
> am trying to recall if any text uses this approach, my QM lecturer 
> did this but not sure if it has its basis in a book you might read.) 
> 

   There are at least two texts that use polarizers (or the like) to explain 
this QM concept.  One is by A. P. French (called Intro Quantum Mechanics,
I think) and the other is Dirac's beautiful exposition _Principles of 
Qunatum Mechanics_.  Of the two French's book is probably a bit easier to
tackle but Dirac's book is worth the effort. 

____________________________________________________________________________
B. Luther                             |  
Internet: Luther@mps.ohio-state.edu   |  "Seek simplicity and distrust it"
Ohio State University Physics Dept.   |              -Whitehead
____________________________________________________________________________
From: burt@aupair.cs.athabascau.ca (Burt Voorhees)
Newsgroups: sci.physics
Subject: Re: Quantum Zeno Effect, Part 1.
Date: 4 Oct 92 05:49:54 GMT


  Back in the late 70's I was quite interested in this effect after
reading the Misra & Sudarshan paper.  I happened to encounter
Sudarshan and asked him whether this meant that if I watched myself
continuously I would not age.  He immediatly began a discussion of the
relative merits of various forms of meditation.
  At this late date, having failed to keep a careful enough eye on
my self, I am not in a position to answer this question from experience.
But, depressing thought, it would seem that this self-observation would
have to be at the molecular level.  Too bad.
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: BAEZIAN Physics and astronomy [was: Space-time IS a semi-Riemannian manifold (?)
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Tue, 6 Oct 92 02:36:01 GMT

In article <1992Oct5.091234.29484@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:
>jbaez@riesz.mit.edu (John C. Baez) writes:
>: 
>: I am awed by your certainty.  Many of the best researchers in quantum
>: gravity would dearly like to know whether spacetime is a
>: semi-riemannian manifold.  What info do you have that they don't? 
>: Barring seances with Einstein's ghost, I would prefer to say
>: "spacetime is well modelled by a semi-riemannian manifold on
>: sufficiently large distance scales."  
>
>Two points. First, nobody in that discussion mentioned quantum effects.
>So naturally what I meant was that CLASSICAL spacetime IS a
>semi-riemannian manifold. 

In other words, in a certain model of physics spacetime is represented
by a semi-Riemannian manifold.  That sounds compatible with the sentence
you were lambasting, namely "spacetime is modelled by a semi-Riemannian
manifold".  But anyway, it sounds like the model/reality distinction was
not the main thing on your mind...

>The kind of thing I am criticising is the
>speculation that big-bang type singularities are meaningless because no
>clock could endure arbitrarily large tides. To that I reply that
>CLASSICALLY time is well defined mathematically [as the length of a
>timelike worldline] and that I am not interested in clocks. In short, I
>was repudiating operationalism, not quantum gravity!

I think that all sorts of semi-bogus philosophizing is acceptable as a
warm-up to doing honest physics and mathematics, but it is certainly no
substitute.   If anyone seriously makes the argument you are
criticizing, I suppose I would have to take your side (much as it pains
me to ever agree with you).  Nature is certainly under no obligation to
provide us with clocks that function at arbitrarily high g-forces.  

>ON THE OTHER HAND I am extremely sceptical of statements such as "at
>sufficiently small length [huh? what's that?] scales, spacetime is
>replaced by [wormholes, worms, knots ,loops, strings, etc]. Spacetime is
>the set of all events. What does it mean to say that events are
>"replaced" by anything? : 

What's getting replaced is not events but the notion that they are in 
one might replace this notion WITH, but it's definitely worth keeping in

mind as a possibility.  It would have to be some structure which is good
at looking like a manifold at larger distance scales.
From: helix@vesta.unm.edu (heli  fairweather)
Newsgroups: sci.physics
Subject: Quantum Mech. Textbooks
Date: 29 Sep 92 03:25:43 GMT
Organization: University of New Mexico, Albuquerque

I am looking for used copies of Quantum Mechanics books. I need both
volumes of Cohen-Tannoudji and both volumes of Messiah. Please e-mail
me at the address below if you have either of these you would like to
sell.

Thanks,
Helix Fairweather
Physics and Astronomy   
University of New Mexico

helix@vesta.unm.edu
From: bafta@cats.ucsc.edu (Shari L Brooks)
Newsgroups: sci.physics
Subject: Re: Do physicists wax metaphysical?
Date: 7 Oct 1992 02:49:11 GMT
Organization: University of California - Santa Cruz, CA, USA
NNTP-Posting-Host: am.ucsc.edu
Keywords: This is humor.


In article <1992Oct6.012221.28431@access.usask.ca> choy@skorpio.usask.ca (I am 
a terminator.) writes:
>
>  + The universe is a large computing device bound and run by God knows
>    what (but God knows I'm going to find out). We're here as something
>    is being computed (or the machinery is idle).
>Henry Choy

The Earth is a large computing device created and operated by mice.  We're
here to discover the question whose answer is 42.
-Douglas Adams

:)

-- 
If you blow fire against the wind, take care to not get the smoke in your eyes.
      Big & Growly Dragon-monster        |       bafta@cats.ucsc.edu
     ------> shari brooks <-------       |       bafta@ucscb.ucsc.edu
                             All opinions are my own.
Organization: Doctoral student, Urban and Public Affairs, Carnegie Mellon, Pittsburgh, PA