HDTenEightyP/NetNews huggingface dataset:
From: bbowen@megatest.com (Bruce Bowen)
Subject: Re: Black hole insights
Organization: Megatest Corporation
Date: Mon, 25 Jan 1993 20:35:01 GMT

> What I want to know is, when people calculate how much "time" it takes for
> a black hole to evaporate (proportional to M^3 they say), what coordinate
> are they talking about?  I'm still confused by the fact that a test
> particle takes infinite Schwartzschild "t" to pass the horizon, but the
> hole evaporates in finite "t", and I'm not convinced that the "bulging"
> effect people have mentioned is the answer.  Perhaps I'm just being
> irresponsible using Schwarzschild coordinates when M is changing.

  This same thing has occured to me.  I haven't yet seen a satifactory
explanation.  Also, locally, there's nothing really "stressful" about
spacetime at the horizon, so why would an infaller see anything there;
unless to him the evaporation radiation appeared to emminate from the
singularity.


From article <mcirvin.727904072@husc.harvard.edu>, by mcirvin@husc8.harvard.edu (Matt McIrvin):
> Ingoing Eddington-Finkelstein and Kruskal coordinates avoid this difficulty.

> Now, what *I'm* confused about is the situation in which the object has
> a finite mass.  I agree that the horizon will come out to meet the object
> and engulf it, but does this mean the observer will see it wink out
> abruptly?  Forget "coordinate time"-- that's by definition dependent on an
> arbitrary definition.  What do the future light cones do?  Do light cones
> originating arbitrarily close to the engulfment event hug the horizon
> arbitrarily closely, in which case the situation is really no different
> except in detail from the massless one?  Or does something more complicated
> happen?

  I'm not sure about this either.  I am reviewing MTW's chapter on
gravitational collapse, which I think, is an equivalent problem.

  He's a thought problem:

  Say, we have a black hole of mass M.  We drop a small test mass into
it.  We wait long enough for it to get within a small distance epsilon
of the horizon.  We then radially symmetrically dump another amount of
mass M in on top of it.  Very soon in observer/coordinate time the
event horizon has moved far above the position of our small test mass,
so it is well within the event horizon in a finite amount of
schwartzchild "t".  What now is it's coordinate time to reach the
central singularity?

  Here's another question:

  Kruskal coordinates, etc.  are different parameterizations of
spacetime that avoid the coordinate singularity at the horizon that
results in schwartzchild coordinates.  There is of course a mapping
between the two coordinate systems.  What does one get for "r" and "t"
when one maps back into schwartzchild coordinates after the particle
has passed the horizon, and does anyone give these values
significance?  What is the final value of "t" when an infalling
particle reaches the central singularity?


-Bruce
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Poisson brackets, symplectic geometry, quantization - and everything!
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Wed, 27 Jan 93 01:51:25 GMT

I wrote:

Both these approaches [to quantization]
work fine for the LINEAR case in which your phase
space is just C^n (or, basically the same, the cotangent bundle of R^n).
Moreover both generalize the INFINITE-DIMENSIONAL linear case, which is what 
comes up in quantum field theory,

I meant "generalize to the infinite-dimensional case".
From: wessir@shelley.u.washington.edu (bill the cat)
Newsgroups: sci.physics
Subject: possible heat to electricity conversion processes
Followup-To: poster
Date: 28 Jan 1993 07:00:32 GMT
Organization: University of Washington, Seattle
Distribution: world
Reply-To: wessir@u.washington.edu
NNTP-Posting-Host: shelley.u.washington.edu
Summary: open questions to thermo study
Keywords: thermodynamics, electricity, heat energy


Energy being the purpose, we all use energy in the form of electricity.  What
do we have an abundance of?  What do we sometimes spend energy to remove?
Why heat of course.  Does it not seem reasonable that we can extract energy
from hot air and get cool air as a by-product, or get cool air and energy as
a by-product.  Already we know that we can create electricity by using the 
expanding steam created by adding energy to water to run a generator.  
Improovements can be made in this sytem by replacing water with some other
fluid which expands at a lower temperature but great inefficiencies still exist
because of the mechanical generator.  What further improovements can be made?
Are there any other methods of converting heat to electricity?  Are there any
ideas on how to directly convert pressure to electricity?  What other direction
of thought could I go with this?
wessir
From: chl@clw.cs.man.ac.uk (Charles Lindsey)
Newsgroups: sci.physics
Subject: Re: Origin of Limerick?
Date: 24 Jan 93 16:56:45 GMT

In <QfLgMNy00VozMIJkU3@andrew.cmu.edu> vm0h+@andrew.cmu.edu (Vincent J. Matsko) writes:

>The following is my advisor's paraphrase of a limerick he once heard. 
>We would like to use it in a book we are co-authoring, and would
>appreciate a reference.  Has anyone heard of it and/or know its source?

<Limerick deleted>

Well your version doesn't scan particularly well. The version I know is more
like

	There was a young lady named Bright,
	Who travelled much faster than light;
	She went out one day
	In a relative way,
	And returned on the previous night.
From: columbus@strident.think.com (Michael Weiss)
Newsgroups: sci.physics
Subject: The confusion of tongues (was: Trouble understanding bra-ket notation)
Date: 21 Jan 93 10:14:15
Organization: Thinking Machines Corporation, Cambridge MA, USA
Distribution: usa
	<1jd41cINNdh4@gap.caltech.edu> <1jlhucINNrtj@darkstar.UCSC.EDU>
NNTP-Posting-Host: strident.think.com
In-reply-to: ask@ucscb.UCSC.EDU's message of 21 Jan 93 07:04:44 GMT


Whitehead said somewhere that progress in mathematics depends not on
thinking about what you're doing, but in crafting notation that makes you
to do the right thing without thinking.

Dirac's bra-ket notation fills Whitehead's prescription to the letter.
Mathematicians seem to prefer a more thought-ful notation, with
correspondences spelled out.  Dirac writes <v|T for the dual of T operating
on the dual of |v>; glance in a mathematics text and you are apt to find
T* L_v, or something similar.  Again, Dirac writes simply <v|T|w> for
either side of the equation <v,Tw> = <T*v,w>, thereby saving a step in many
computations.

On the topic of mathematicians' vs. physicists' notation, does anyone know
why most mathematicians will write an integral as shown below on the left
(unless they omit the dummy variable x entirely), whereas physicists prefer
the form on the right?

         /                       /
         |  f(x) dx              | dx f(x)
         /                       /

With the left-hand form, the integral sign and the dx act as delimiters.
With the right hand form, the combination of integral sign with dx stands
for a linear operator.  Neither interpretation seems to favor one side of
the cultural divide.

From: kevins@hpspdla.spd.HP.COM (Kevin G Smith)
Date: Tue, 26 Jan 1993 18:58:13 GMT
Subject: Quals Preparation Questions
Organization: HP Stanford Park - Palo Alto, CA
Newsgroups: sci.physics

Hi,  
I would appreciate hearing from university graduate students and faculty in any
of the following related fields,
* physics
* applied physics
* electrical/electronic engineering
regarding preparation for PhD program qualifying examinations.  
Specifically: 
(1) Does your university have a recommended study list of topics
or a syllabus, and what are its contents? 
(2) How about a recommended book list?
(3) Finally, how much time should the "typical" MS level student at your
institution expect to study such review material in addition to study/work 
duties?  (e.g. 1 quarter - 1 year supplementary study)
Please email or post replies.  

Thanks and cheers!

*******************************************
* Kevin G. Smith                          *
* Email: kevins@hpspd.hp.com              *
*******************************************
From: weed-matthew@cs.yale.edu (Matthew Weed)
Newsgroups: sci.physics
Subject: Re: New Physics,Healing & Paranormal 2 "White Paper"
Date: 27 Jan 1993 00:34:28 -0500
Organization: Yale University Computer Science Dept., New Haven, CT 06520-2158
NNTP-Posting-Host: rattlesnake.zoo2.cs.yale.edu

In article <106701@netnews.upenn.edu> jmv@grip.cis.upenn.edu (Jean-Marc Vezien) writes:
>In article <C1H5D6.6Jr@well.sf.ca.us>, sarfatti@well.sf.ca.us (Jack Sarfatti) writes:
>> 
>> Continuing part 2 of my paid for "intelligence analysis" on the impact
>> of New Age Paradigms on the future of medicine, new marketing
>> strategies, new politics, etc. etc. for a high level consortium based
>> in Luxembourg,Geneva,London and Paris. Your (unpaid) comments,
>> criticisms will be included (if of value) in footnotes. I am striving
>> for a balanced objective presentation.
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>I don't think so.
>
>You know Jack, you should try to strive for regaining your sanity instead.
>
>As for your high-level consortium, I challenge you to give any information
>on it. I think you're talking BS.
Second this motion, this is almost as bad as the tripartite conspiracy thing of a couple years ago.
Some of the science seems semi-credible to an undergraduate biologist (me), but the more he says the odder he seems.
>JM.

Matt
-- 
"The nation behaves well if it treats the natural resources as assets 
which it must turn over to the next generation, increased and not 
impaired in valued."  --President Theodore Roosevelt
Matthew Weed	weed-matthew@suned.zoo.cs.yale.edu
From: paul@mtnmath.UUCP (Paul Budnik)
Newsgroups: sci.physics
Subject: Re: hidden variables
Date: 23 Jan 93 16:51:15 GMT
Organization: Mountain Math Software, P. O. Box 2124, Saratoga. CA 95070

In article <1993Jan22.141017.11147@cs.wayne.edu>, atems@igor.physics.wayne.edu (Dale Atems) writes:
> [...]  
> Actually to get at my basic objection we have to step back a bit. The
> premise you quote, if I've understood you, is the conclusion of an
> argument whose premise is "information must be transferred
> instantaneously at a distance when Bell's inequality is violated".
> As I've said before, I consider this a completely reasonable thing
> to say. However, I don't think one can draw any conclusions about
> quantum theory from any argument based on this premise. As a
> physical theory QM is not required to account for a "process"
> which cannot be observed. The correlations which result in the
> violation of Bell's inequality are the only thing it needs to
> explain, and it regards those as a consequence of the twinned
> photons' common origin.

It is the timing associated with those correlations that is critical.
This is an observable macroscopic effect that QM must account for if it
claims to be a complete theory. The timing is not a consequence of the
singlet state or `twinned photons' model. If wave function
collapse is a local Lorentz invariant process, as I suspect it is, then
we will still get the correlations predicted by QM. We will not get the
same timing and we will not get a violation of Bell's inequality.
This singlet state model by itself says nothing about the timing relationship
between when one changes a polarizer angle and when this has an observable
effect. To compute the timing you need to go to the wave function model
and you need to use the collapse postulate. The Schrodinger equation
is local you cannot use it to model the instantaneous transfer of information
that you agree is necessary to produce the predictions of QM.

> Also I don't think it's correct to call collapse a law of physics.
> If one takes probability as a primary concept one needs to describe
> what happens when the observer's state of knowledge changes. If
> this occurs discontinuously, then the description naturally reflects
> that discontinuity.

Collapse is a pretty poor excuse for a law of physics but it is a law
of physics within QM. This is because the wave function in QM is not
just a matter of describing what we know about an underlying objective
reality. That is true of probability distributions in classical physics.
In QM the wave function model is the *only* model we have. There is
no underlying objective reality that it refers to. Bell's theorem shows
this law has experimentally verifiable consequences.

Paul budnik
From: mcirvin@husc8.harvard.edu (Matt McIrvin)
Newsgroups: sci.physics
Subject: Re: Truth vs beauty in physical theories
Date: 25 Jan 93 21:46:37 GMT
Article-I.D.: husc.mcirvin.727998397
 <0FswXB1w165w@1776.COM><mcirvin.727989335@husc.harvard.edu> <MATT.93Jan25122932@physics2.berkeley.edu>

matt@physics2.berkeley.edu (Matt Austern) writes:

>I would take out that "possibly".  That is: I don't know whether or
>not a Higgs really exists (I'm skeptical), but whatever it is that
>breaks SU(2)xU(1), I don't think it can be done by pure gauge
>interactions.  Even if you believe in Technicolor, chiral symmetry
>breaking isn't enough: you need something to give mass to the
>technifermions, so you've only deferred to problem to a higher energy
>scale.

You mean "give mass to the ordinary fermions," don't you? 

People are still messing around over here with somehow doing that
with extended technicolor bosons, with a "sideways" vertex that
changes a fermion to a technifermion.  To me, it seems that 
the most realistic models are incredibly baroque, and it's
disquieting to think that the whole motivation is to solve the
gauge hierarchy problem so that the buck can be passed to some
truly humongous GUT gauge group up at 10^15 GeV. 
-- 
Matt McIrvin
From: u108502@beta.lanl.gov (Andrew Poutiatine)
Newsgroups: sci.physics
Subject: Re: satellite orbits
Date: 26 Jan 93 16:02:10 GMT
Organization: Los Alamos National Laboratory

In article <1993Jan22.015334.9290@leland.Stanford.EDU> ledwards@leland.Stanford.EDU (Laurence James Edwards) writes:
>In article <1993Jan21.213632.3246@newshost.lanl.gov>, u108502@beta.lanl.gov (Andrew Poutiatine) writes:
>|> In article <376oXB3w165w@netlink.cts.com> bigbro@netlink.cts.com (Kenneth Sullivan) writes:
>|> >Quick easy question, this is mostly to settle an arguement
>|> >
>|> >a.)what keeps a satellite in orbit
>|> >and 
>|> >b.)just how wrong is the idea of centrifugal/centripidal "force"?
>|> >thanks
>|> >
>|> [...]
>|> If the satellite is moving too slowly initially to maintain a stable orbit, 
>|> then it falls, speeding up, until a stable orbit is maintained, unless of 
>|> course it enters the atmosphere or hits the ground or something.
>|> 
>|> The gravitational force is toward the Earth, and is hence a centripital force.
>|> In this simple example there is no centrifugal force.
>                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>If the earth exerts a centripetal force on the satellite I would think the
>satellite exerts a centrifugal force on the earth, as you mention subsequently
>with the example of the ball and string.
>
>Larry Edwards

Yes, you would be right to think this.  I should have been more clear on what
in fact I meant, but I did not think anyone in this newsgroup could mis-
understand what I was saying.  I meant that in the simple example described,
and considering _only_ the satellite, and the forces acting on it.

By the way, how on Earth did you learn to pick nits in such a competent manner?

-AIP
From: rhatcher@fnala.fnal.gov
Newsgroups: sci.physics
Subject: Re: TIME HAS INERTIA  -   INDRA  SINHA'
Date: 28 Jan 93 10:25:39 -0600
Organization: Fermi National Accelerator Lab
NNTP-Posting-Host: fnala.fnal.gov

In article <1541700026@gn.apc.org>, antennae@gn.apc.org writes:
> Hello again,
> 
> what I meant was that you don't become a scientist as great as those
> named without questioning everything every day.
> 
> all the best,
> 
> indra

Okay, okay, some one is going to do it ... might as well be me:

I question the validity of such a generalization that the only
route to becoming a great scientist is to question *everything*
*every* day.  I think some of those great scientists under discussion
did indeed come to accept a large majority of occurances as "given"s
that did *not* need questioning, each and every day.  Maybe what
you meant was "something new, every day" or "everything, some days"?

Indra, as previously discussed in this or a related group I'm going
to invoke CARP (Cite Appropriate References, Please) on your statement.
I'd just love to see documentation that each and every great scientist
(named previously) did indeed question everything on a daily basis.

Hey, don't get mad a me for disbelieving in your little platitude,
I'm only following it to the letter.

-robert
 hatcher@msupa.pa.msu.edu


Newsgroups: sci.physics
From: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: Selective Ethics for Sci. Phys.Moderated?
Organization: Whole Earth 'Lectronic Link
Date: Fri, 22 Jan 1993 02:39:15 GMT


This is clearly a matter of selective ethics. If sci.physics.research is
not to be a mockery shunned by serious physicists, then there must a single
standard, a "rule of law". Any moderator who does not have the self-control
to refrain from flames in response to a reasonable, or even an
unreasonable, question is not fit to moderate. This is obvious.
From: schumach@convex.com (Richard A. Schumacher)
Newsgroups: sci.physics
Subject: Re: Big Bang Alternates
Date: 23 Jan 93 19:47:10 GMT
Organization: CONVEX Computer Corporation, Richardson, Tx., USA
X-Disclaimer: This message was written by a user at CONVEX Computer
              Corp. The opinions expressed are those of the user and
              not necessarily those of CONVEX.

>     Velocity is a redshift-blueshift mechanism.  Other mechanisms are
>redshift-only.  Examples are tired light and gravitational redshifts.
>Several redshift-only mechanisms work very well for alternate cosmologies.

Sorry. I should have said, "absence of any velocity independent
redshift mechanism which is not grossly ad hoc". To counter Feynman's
objection to dark-matter mediated tired light, you postulate that 
the matter is "resisting entities individually so small that the
>energy loss to photons is smooth and continuous, not in discrete collision
>events with quantum-sized particles."
You also mention gravitational redshift. If this is the mechanism,
why does it only work for distant objects, which otherwise appear
identical to nearby objects?

The big bang is elegant and predictive with few assumptions. Show us
an alternate theory that makes the same predictions to the same
accuracy with fewer assumptions. (Yeah, I know, your book will be
out real soon now.)
From: benjie@exeter.uucp (Android)
Newsgroups: sci.physics
Subject: test
Date: 25 Jan 93 20:37:18 GMT
Organization: NCC 1701-D U.S.S. Enterprise

test
Newsgroups: sci.physics
From: holerbch@phoenix.Princeton.EDU (Uwe Hollerbach)
Subject: Re: Home made monopoles
Originator: news@nimaster
Organization: Princeton University
Date: Mon, 25 Jan 1993 18:56:40 GMT

In article <1993Jan25.171223.5051@novell.com> dseeman@novell.com (Daniel Seeman) writes:
>In article <1jr3uiINNcjk@mirror.digex.com> bdoa@digex.digex.com (Barry Adams) writes:
>>   
>>
>>                     Home made magnetic monopoles
>>                     ============================
>>
>>   Contrary to popular belief , magnetic monopoles exist and are easy to
>>make . Take a Steel hemisphere and cut a concentric hemisphere cut of the
>>middle , now magnetize the hemisphere such that the domains of the object
>>are aligned with the north (south) pole pointing outwards. Now stick two of
>>the hemispheres together forming a sphere  (glue strong enough to resist
>>the magnetic repulsion of the hemispheres is required) you now have your
>>magnetic monopole :-) , since any observer will see the object having a north
>>pole only (unless they cut it open).
>>   Of course the configuration is unstable and the domains will slowly try
>>to rearrange themselves to a more stable state. And the magnetic force still
>>decays like a dipole. Such objects might to useful as frictionless bearings.
>>
>>Barry Adams
>>
>>   
>In this experiment, we are to assume that what we cannot diretly "see (ie. the
>inside of the sphere)" does not affect the problem.  Just because we "know" the
>South Pole exists in the volume cavity inside doesn't mean we can actually
>"see" it.  Hmmmm, it seems a bit like an illusion to me (smoke and mirrors to
>be sure) but the application may be useful.  The application sure does satisfy
>the apparent identifying criterion (compass always points one way near the
>monopole).  I would like to hear other opinions (experiences) with this idea.
>
>dks.


No. Actually, even this won't happen. The actual configuration of the
magnetic field will be as follows: there will be two regions at the
poles of the sphere where the north-seeking end of the compass needle
will be attracted to the sphere, and around the equator of the sphere
there will be a region where the south-pointing end of the needle will
be attracted to the sphere. This is actually one kind of quadrupole
configuration, I believe. If it were possible to hide the south poles
in the cavity like this, it would in fact _be_ a monopole (more
technically, the magnetic field would have a monopole component, in
addition to having other components). Best regards,
-- 
Uwe Hollerbach          uh@acm.princeton.edu  or  uh@alumni.caltech.edu
"In His infinite mercy, Allah does not subtract from one's alloted span those
hours which are spent in contemplation of net.news. All praise be to Allah."
-- an obscure commentator on the early work of Al-Khowariszmi
Xref: sparky sci.physics:23538 sci.skeptic:22899 alt.paranormal:2847 alt.sci.physics.new-theories:2852 rec.arts.startrek.tech:7781
From: lindsay+@cs.cmu.edu (Donald Lindsay)
Newsgroups: sci.physics,sci.skeptic,alt.paranormal,alt.sci.physics.new-theories,rec.arts.startrek.tech
Subject: Re: New Physics, Healing, Paranormal
Date: 26 Jan 93 21:41:38 GMT
Article-I.D.: cs.C1HDLF.D4D.2
Organization: School of Computer Science, Carnegie Mellon


sarfatti@well.sf.ca.us (Jack Sarfatti) writes:
>I have been told that I am a "super star" in some powerful
>circles that have decided that traditional universities are "brain dead"
>and that something new-age is needed.

And you're humble, too, apparently.

>How is the new physics different from the old physics? 

The main difference is that the old physics exists to explain
experimental evidence. You, on the other hand, don't seem to make
much mention of evidence.

Are your theories falsifiable?
-- 
Don		D.C.Lindsay	Carnegie Mellon Computer Science
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Newsgroups: sci.physics
Subject: Re: Questions on:  Black-Hole Thermodynamics
Date: 25 Jan 1993 20:04 CST
Organization: Texas A&M University, Academic Computing Services
Distribution: world
NNTP-Posting-Host: zeus.tamu.edu
News-Software: VAX/VMS VNEWS 1.41    

rbsalgad@rodan.acs.syr.EDU (Rob Salgado) writes...
>4) What is the status of the cosmic censor conjecture?

A counterexample can be found in MTW. To this day people try
to find loopholes which could invalidate the counterexample, because
they want to believe Cosmic Censorship.

Dave Ring
dwr2560@zeus.tamu.edu
From: ucacgcj@ucl.ac.uk (Gordon C Joly)
Newsgroups: sci.physics
Subject: Re: Super-Strings
Date: 28 Jan 93 18:00:38 GMT
Organization: Bloomsbury Computing Consortium

In article <25441@galaxy.ucr.edu> baez@guitar.ucr.edu (john baez) writes:
>[...]There is so much powerful mathematics associated with
>Riemann surfaces that it is natural to want to use it... and this is
>what people have done (greatly pushing forward the subject in the
>process).   Of course, it's not clear whether Nature finds this mathematics
>as tempting as we do. 

It is also not clear whether spacetime is "foam" or not (that is to
say has a Winding number of one).

There is an assumption that we live in a (continuously) differential
manifold, which may not be the case.

Gordon.



--
Gordon Joly      Phone  +44 71 387 7050 ext 3703      FAX  +44 71 387 1397
Internet: G.Joly@cs.ucl.ac.uk                            ucacgcj@ulc.ac.uk
Computer Science, University College London, Gower Street, LONDON WC1E 6BT
Newsgroups: sci.physics