HDTenEightyP/NetNews huggingface dataset:
From: tycchow@riesz.mit.edu (Timothy Y. Chow)
Subject: Re: What's a manifold?
Organization: None.  This saves me from writing a disclaimer.
Date: Thu, 5 Nov 92 17:47:51 GMT

In article <1992Nov5.060400.14203@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
>Ah, now this is starting to sound very interesting and helpful.  What I
>don't understand here is how "living in R^n" is of itself creating
>complexity and obscurity.  I can see that the arbitrariness of f might
>get in the way.  But where does the complexity and obscurity creep in
>if for example we define a manifold to be a smooth retract of an open
>subset of R^n?  (This is essentially taking the existence of tubular
>neighborhoods as definitive of manifolds, and is how Bill Lawvere likes
>to think of them.)

Well, for a start there are some definitions of manifolds that allow
things that don't embed in R^n.  But even if we exclude these cases from
consideration, there is still good reason not to define manifolds as
subsets of R^n.  The point is that there are many different subsets of
R^n that represent the "same" manifold.  So we really should talk about
equivalence classes of subsets of R^n, under some suitable equivalence
relation.  Actually it is worse than that since we might want to identify
certain subsets of R^3 with certain subsets of R^4.  This is why I think
it's cleaner to lay down the axioms for a topological space and use that
as the basis for the definition of a manifold, rather than have to bring
in this huge equivalence class of subsets every time you want to talk
about a manifold.

In fact, I think that despite appearances your retract definition of
manifold actually contains topological axioms implicitly.  Don't you
really want to say that a manifold is something *homeomorphic* to a
smooth retract of an open subset of R^n?  Once you do this you've already
taken the implicit step of embracing the axiomatic approach to topology.

None of this is to say that it isn't often convenient to take a subset
of R^n to *represent* a manifold.  Your point is well taken---we don't
necessarily want to avoid R^n altogether once after we've abstracted
away from it.  But I still think it's simpler to *define* a manifold
axiomatically rather than make the definition essentially dependent on
subsets of R^n.
-- 
Tim Chow     tycchow@math.mit.edu
Where a calculator on the ENIAC is equipped with 18,000 vacuum tubes and weighs
30 tons, computers in the future may have only 1,000 vacuum tubes and weigh
only 1 1/2 tons.                               ---Popular Mechanics, March 1949
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Newsgroups: sci.physics
Subject: Re: Religion & Physics Don't Mix
Date: 5 Nov 92 21:14:04 GMT
Organization: Intel Corp., Chandler, Arizona
NNTP-Posting-Host: alfalfa.intel.com

In article <1992Nov5.044405.27584@murdoch.acc.Virginia.EDU> crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:
>    According to Webster, definition 4), truth is God.  So God
>    is science?

According to Webster, a faggot is a bundle of sticks,
but then Webster works in colloquial ways.

				--Blair
				  "No more Latin.
				   My TI translator
				   is getting warm..."
Newsgroups: sci.physics
From: matmcinn@nuscc.nus.sg (Brett McInnes)
Subject: mcinnes on astrology
Organization: National University of Singapore
Date: Wed, 11 Nov 1992 02:47:44 GMT

He doesn't like it; it smacks too much of Mach's principle.
From: refling@sloth.eng.uci.edu (John P. Refling)
Subject: Parts needed for AO Spencer microscopes for children's hospital
Newsgroups: sci.physics
Organization: University of California, Irvine
Date: 10 Nov 92 08:31:02 GMT
Distribution: usa


I have been put in charge of repairing 2 American Optical Spencer Microscopes
for a children's hospital in Equador.  I need the following (free or very
cheap):

2 eyepieces x10 (a.o. 180 or equivalent)
8 objectives (assortment of powers)
2 base lite power supplies

If you have any leads for any of these items, your information would be
appreciated.  (I will be away on business for 2 weeks, but will respond
when I return).

John Refling
Electrical Engineering Dept.
University of California
Irvine, CA  92717

          [ please reply to me directly, not to the newgroup ]
Newsgroups: sci.physics
From: lucas@watson.ibm.com (Bruce D. Lucas)
Subject: space
Date: Fri, 06 Nov 1992 21:11:15 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
Organization: IBM T.J. Watson Research Center

How do we know space is three-dimensional, or space-time
four-dimensional?  Is there a simple experiment one can do to
determine the dimensionality of space or of space-time?

(I'm thinking of dimensions of ordinary (nearly) Euclidean space
observable by ordinary means, not such exotic things as the very
highly curved extra dimensions that I understand are postulated
by some theories.)

Bruce Lucas
Newsgroups: sci.physics
From: ddixon@nyx.cs.du.edu (David Dixon)
Subject: Higgs mass mechanism and e+e- anihilation
Organization: Nyx, Public Access Unix @ U. of Denver Math/CS dept.
Date: Sun, 8 Nov 92 23:37:12 GMT

If electron mass comes from the coupling to a scalar Higgs field, then
what would the mechanism be for converting this mass to the energy in
a gamma-ray if the electron is annihilated (one n or two?) by a positron?
Does this also account for the relativistic mass?  How about the
electromagnetic binding energy of a hydrogen (or other) atom?

Just curious.

				Dave
Xref: sparky sci.physics:18177 sci.math:14435
From: matt@physics2.berkeley.edu (Matt Austern)
Newsgroups: sci.physics,sci.math
Subject: Re: What's a manifold?
Date: 5 Nov 92 10:11:48
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
	<1992Nov5.004804.24757@galois.mit.edu>
	<1992Nov5.035214.25991@galois.mit.edu>
	<1992Nov5.060400.14203@CSD-NewsHost.Stanford.EDU>
Reply-To: matt@physics.berkeley.edu
NNTP-Posting-Host: physics2.berkeley.edu
In-reply-to: pratt@Sunburn.Stanford.EDU's message of Thu, 5 Nov 1992 06:04:00 GMT

In article <1992Nov5.060400.14203@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:

> Ah, now this is starting to sound very interesting and helpful.  What I
> don't understand here is how "living in R^n" is of itself creating
> complexity and obscurity.  I can see that the arbitrariness of f might
> get in the way.  But where does the complexity and obscurity creep in
> if for example we define a manifold to be a smooth retract of an open
> subset of R^n?

The problem with that is that it focuses too much on an aspect of a
manifold that just isn't terribly fundamental.

For example: the 2-sphere S^2 and a Klein bottle are both perfectly
nice two-dimensional manifolds.  However, S^2 can be embedded in R^3,
and a Klein bottle has to be embedded in R^4.  There's nothing
particularly fundamental or interesting about that difference, and it
would be a shame to have a definition of a manifold that obscured the
essential similarity between these two two-dimensional manifolds.
--
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!
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: nuclear waste disposal
Date: 6 Nov 92 22:25:12 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Organization: SCRI, Florida State University

In article <1992Nov4.210346.2724@aoa.aoa.utc.com> carl@aoa.aoa.utc.com (Carl Witthoft) writes:
>
>There have been newspaper articles on and off thru the years 
>which describe "gypsy" workers who do maintenance on nuclear
>power plants.  By being mobile and lying a bit :=), they get
>lots of cash and lots of radiation.
>Whether this still happens I don't know.

This certainly still goes on.  Of course, these "gypsy" workers are 
almost the exact opposite of a cloistered monastic group maintaining 
a storage facility, where the main job is to make sure no one breaks 
in and to monitor test wells for leaks.  A storage facility would 
be filled up (mostly by remote control) over a number of years and 
then sealed for "all" time.  The processing of the material to be 
stored does not require exposure to extremely high radiation areas. 

The opposite is true of maintenance work inside the containment 
building of a reactor.  There you can get your 3-month limit in a 
few minutes.  Since the reactor staff need to be able to work in 
a "radiation area" -- they would be excluded from certain areas 
if they reached their limit -- it is common to use temporaries 
trained to a single simple task (say turn a bolt) and send them 
on their way when they are done.  Quite a few were used at the TMI 
cleanup if I recall correctly.  These people are supposed to go back 
to their regular jobs, since they should get no more radiation for 
another 3 months or more, but sometimes they lie and work at another 
site.  The SS-number based system is *supposed* to keep this from 
happening, but ... 

--
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: sarfatti@well.sf.ca.us (Jack Sarfatti)
Subject: Is God malicious after all?
Organization: Whole Earth 'Lectronic Link
Date: Fri, 13 Nov 1992 07:29:28 GMT


The simplest argument to make against the quantum connection signal in my
model is to say that local unitarity in the single-photon sub-Fock space
requires:

phi + arg<a,e,+|a,o,+> = pi/2

and the receiver "fringe" term is

sin(2theta)cos(phi + arg<a,e,+|a,o,+>) = 0 exactly in a unitary "screening"
or phase-renormalization preventing "telepathy" at all costs.  Does GOD
abhor quantum connection signals?  Is HE malicious after all?

Of course it is not obvious that the single-photon unitarity is relevant to
the photon-pair sub-Fock space in which arg<a,e+|a,o,+> may be anything like
in spontaneous broken symmetry of ferromagnetic ground states - because
the pair state norm is conserved under spin disentanglement. Thus, the
argument from single photon superpositions is not convincing apriori.
Let experiment decide!
zaphod.mps.ohio-state.edu!moe.ksu.ksu.edu!hobbes.physics.uiowa.edu!news.iastate.edu!pv343f.vincent.iastate.edu!abian
Newsgroups: sci.physics
Subject: TIME HAS INERTIA        ABIAN REPLIES TO M.S.T.  WATTS
From: abian@iastate.edu (Alexander Abian)
Date: 10 Nov 92 02:56:10 +1000
Keywords: (A1) and (A2)

                                          11-9-92
Date: 10 Nov 92 04:13:13 GMT
Organization: Iowa State University, Ames IA

Mr. Watts,                          

   I tried to read your two  page posting. It is difficult for me 
to manage to catch your whole posting since (repeating your words)
the construction of your sentences are grammatically faulty.  If
you rewrite your posting (again repeating your words) in correct
English, I may  reconsider replying to it.
   In the meantime you are proving the validity of my (A1) and
so do I too:

(A1)     THE TENDENCY OF MAINTAINING THE STATUS QUO, REACTION TO PRO-
         VOCATION AND THE TENDENCY OF MAINTAINING AGAIN A STATUS QUO.


-- 
   The tendency of maintaining the status-quo, Reaction to provocation and
                The tendency of maintaining again a status-quo.  
    TIME HAS INERTIA  and some energy is lost to move Time forward  
  E = mcc  (Einstein)    must be replaced by    E = m(0) exp(-At) (Abian)
From: matt@physics3.berkeley.edu (Matt Austern)
Newsgroups: sci.physics
Subject: Re: Religion & Physics Don't Mix
Date: 10 Nov 92 12:41:25
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
Distribution: na
	<1992Nov7.212535.312@aee.aee.com>
	<1992Nov8.160429.14488@galileo.physics.arizona.edu>
Reply-To: matt@physics.berkeley.edu
NNTP-Posting-Host: physics3.berkeley.edu
In-reply-to: lnh@soliton.physics.arizona.edu's message of 8 Nov 92 16:04:29 GMT

In article <1992Nov8.160429.14488@galileo.physics.arizona.edu> lnh@soliton.physics.arizona.edu (sometimes a Wombat) writes:

> gene@aee.aee.com (Gene Kochanowsky) writes:
> > If there is any complete nonsense here, it is that a person can be truely
> > religious and scientific in his religion at the same time. It is absurd, 
> > illogical and speaks volumes of misunderstanding on the part of that 
> > person of what is the basis of both science and religion.
> 
> Tell that to Einstein.

I don't know whether or not it is correct to say that Einstein was a
religious man, but he certainly was not religious in a conventional
sense.

Einstein once said that his religious beliefs were similar to those of
the philosopher Spinoza.  Just as a reminder, Spinoza was shunned by
the Jewish community of his city because they thought he was an
atheist.  (I don't think that they were right, but it is quite clear
from even a cursory examination that Spinoza's beliefs had almost
nothing to do with anything that is normally regarded as Jewish.)

People are sometimes misled by a few aphorisms of Einstein's into
thinking that he was conventionally devout.  He wasn't.
--
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!
From: ramsay@unixg.ubc.ca (Keith Ramsay)
Newsgroups: sci.physics
Subject: Re: Sarfatti to Ramsay NO! 10^3XNO& Wheeler's delayed choice.
Date: 11 Nov 1992 00:22:49 GMT
Organization: University of British Columbia, Vancouver, B.C., Canada
NNTP-Posting-Host: unixg.ubc.ca

In article <BxFI6v.H04@well.sf.ca.us> sarfatti@well.sf.ca.us 
(Jack Sarfatti) writes:
>* The important point is that we must not assume that
>
>|a,e,+><a,e,+| + |a,o,+><a,o,+| = 1
>
>That is the mistake that led to the bogus "missing factor of 2" and which
>is still hanging you up Ramsay.

Not at all. You're making guesses about what I'm thinking-- I never
said anything of the kind. There never was any "missing factor of 2"--
this is your phrase.

>In fact, it is no contradiction to say that
>
>|<a,e,+|h>| = |<a,o,+|h>| = 1
>
>because the geometry is such that both e and o beams go to h with
>certainty.  Therefore, everything is unitary locally on each end!

It *is* a contradiction to claim all of these things. In order for the
evolution to be unitary, we must have <a,e,+|a,o,+> = 0. Since
|a,e,+>, |a,o,+>, and |h> are all states, they must be normalized:
hence <a,e,+|a,e,+> = <a,o,+|a,o,+> = <h|h> = 1. Now you want to claim
that it is possible to have |<a,e,+|h>| = |<a,o,+|h>| = 1 as well. It
is not possible to have all of those relationships hold among three
ket-vectors |a,e,+>, |a,o,+> and |h>.

Why? The simple answer, if you know the vector geometry, is that the
only way for two normalized vectors to satisfy |<a,e,+|h>|=1 is for
the one, |a,e,+>, to equal e^{it}|h> for some phase angle t. I.e.,
they represent the same state with a different phase. For this to hold
for both |a,e,+> and |a,o,+> with |h> would imply that |a,e,+> and
|a,o,+> are such multiples of |h>, and thus of each other. But this
contradicts the orthogonality <a,e,+|a,o,+>=0.

Physically, what this means is that the only way to ensure that two
states are "cofinal" in this way is for them to differ only by a phase
in the first place. This is the physical principle you have to make
your peace with, Sarfatti.

Which of those claims do you now want to deny?

Your optics is simply wrong; you can't just claim that there is one
state |h> at the end because it looks to you like there should be.
There are many possible states for the photon to be in at the end.
You can't just say, "the beams combine coherently" because you hope
that it can be done by focusing them well. Coherence is not so
trivially obtained, and the mistake of thinking it *can* be will
manifest itself directly in further erroneous calculations.

Keith Ramsay
ramsay@unixg.ubc.ca
Newsgroups: sci.physics,sci.math
From: dy@shire.math.columbia.edu (Deane Yang)
Subject: Re: Covariant vs. Lie Derivative in Gen. Rel.?
Organization: Mathematics Department, Columbia University
Date: Wed, 11 Nov 1992 22:55:12 GMT
X-Posted-From: shire.math.columbia.edu
NNTP-Posting-Host: sol.ctr.columbia.edu

In article <1drukoINN801@darkstar.UCSC.EDU> ask@ucscb.UCSC.EDU (Andrew Stanford Klingler) writes:

>JB:
>
>>
>>To repeat: The connection allows you to compare tangent vectors at two
>>points of the manifold given only a curve connecting them; the Lie
>>derivative requires a whole vector field, to generate a flow that "drags
>>tensors along". 
>>
>The distinction you're making sounds kind of phony; after all one can
>define a connection using a vector field or a field of one-forms (I may
>be limiting myself to principal fiber bundles here).  It seems like the
>flow is just buried in the structure for a connection (in some sense a
>connection gets you "more than a flow" - the local family of geodesics
>through a point).  Without a connection, you have no way to compare vectors
>at two different points, so you have to transport tensors out, then back
>to the same point and compare them there.  With a connection, you have
>"flow in every direction" (geodesics thru the point) so parallel transport
>vectors from a point to any other point and compare them there.  From this
>point of view Lie derivatives and covariant derivatives represent the
>same geometric thing, I think.  Am I way wrong here?
>
>

Jon Baez, I hope, will have a more complete explanation, but yes
you're way off here. The covariant derivative and the Lie derivative
are very different things.

For one thing, a connection is something that can live in any
vector or principal bundle, whereas the Lie derivative is
only well defined for bundles associated to the tangent bundle.

Secondly, the connection is an additional structure that one
imposes on a bundle; the Lie derivative depends only on
the smooth structure on the manifold.

The easiest thing to do is to ponder this: On a tangent bundle
with a torsion free connection (like the Levi-Civita connection
of a Riemannian metric), 
The Lie derivative of a vector field W with respect to a vector
field V is

L_V W = [V,W] = D_V W - D_W V,

where L denotes Lie derivative and D denotes covariant derivative.

Addressing your discussion a little more directly, the point is
that whereas a connection allows you to parallel translate a
single vector from one point to another, if you have a global
vector field, you can't transport vectors between two arbitrary
points, but you can transport it between two points that lie
on the same integral curve of the vector field. In other words,
you can push forward a second vector field using the 1-parameter
flow of diffeomorphisms induced by the first vector field.
The Lie derivative is defined using this means of transporting
vectors.
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: the Universe in N postulates, where N is small
Date: 9 Nov 92 23:40:29 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

hoyt@isus.UUCP (Hoyt A. Stearns jr.) writes:
>G can be calculated from basic Reciprocal System principles to
> the minimum accuracy of the three numbers used as a starting point:
>	c, Avogadro's number, and the Rydberg frequency.

>-- 
>Hoyt A. Stearns jr.|hoyt@          | International Society of Unified Science|
>4131 E. Cannon Dr. |isus.tnet.com -| Advancing Dewey B. Larson's Reciprocal  |
>Phoenix, AZ. 85028 |ncar!enuucp!   | System- a unified physical theory.      |
>voice_602_996_1717 telesys!isus!hoyt The Universe in two postulates__________|

You know, I bet Abian really pisses the Larsonians off.  Here they've
been going along calculating the whole of physics from just two
postulates, showing up all us orthodox physicists with their
theoretical parsimony, when along comes this UPSTART Abian who
can derive everything from just ONE principle.  Beaten at their own
game.  They'd better figure out how to derive it all from ZERO
postulates if they want any respect from me anymore!
Newsgroups: sci.physics
From: alison@wsrcc.com (Alison Chaiken)
Subject: Re: Solid-state doesn't use QED! (Was Re: Particle Research)
Organization: W S Rupprecht Computer Consulting, Fremont CA
Date: Tue, 10 Nov 1992 05:28:26 GMT

matt@physics.berkeley.edu (Matt Austern) writes:
>My understanding is that solid-state theorists do indeed work with
>models in which this happens.  (e.g., massive photons in
>superconductors) It wouldn't surprise me, though, if solid-state
>people know it by a different name than the "Higgs mechanism."  It
>certainly is a very general concept, and it was independently
>discovered by many people.  One book, in fact, refers to it as the
>Brout-Englert-Higgs-Guralnik-Hagen-Kibble mechanism!

Ah, you are referring to the "spontaneously broken gauge symmetry" in
superconductors.  When this subject came up in the "Field theory of
solid-state" course I took, no one's name was associated with it.  The
gist of the lecture was that the phase acquired by the complex
Bardeen-Cooper-Schrieffer wavefunction broke gauge symmetry.  The
broken symmetry led to a sort of

(particle number)(wavefunction phase) >= 2*pi

uncertainty rule, which showed that macroscopic quantum wavefunctions
necessarily involve an uncertain number of particles.  Using this
argument, one can justify harmonic-oscillator-like ladder operators to
create and destroy quasiparticles.  The intuitive justification in the
superconductivity case is that destroyed Cooper pairs become
quasiparticles, i.e. normal electrons.  Good God, are massive photons
involved here somewhere?  I don't recall it from this discussion.

I recall that there was a Goldstone boson associated with the broken
symmetry, but some hand-waving argument was used to rescale its energy
up to some finite value, probably the superconducting gap energy.  Is
this rescaling where the Anderson-Higgs mechanism comes in?

-- 
Alison Chaiken 				alison@wsrcc.com
(510) 422-7129 [daytime] 		or chaiken@cmsgee.llnl.gov
Look if you like, but you will have to leap.
From: tobis@meteor.wisc.edu (Michael Tobis)
Newsgroups: sci.physics
Subject: Re: TIME HAS INERTIA
Keywords: I don't have TIME for this, but INERTIA makes me do it, no MATTER
Date: 11 Nov 92 20:37:58 GMT
Article-I.D.: meteor.1992Nov11.203758.16635
Organization: University of Wisconsin, Meteorology and Space Science

In article <1992Nov11.102739.10500@ugle.unit.no> kim@Lise.Unit.NO (Kim Gunnar St|vring \yhus) writes:
>Abian feeds on replies. Please don't feed him.

But he has just RIGOROUSLY proved that 1 + z + z^2 = 0 for all values of z !!
Doesn't this result demand further attention?? :-)

mt
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Newsgroups: sci.physics
Subject: Re: Religion & Physics Don't Mix
Date: 9 Nov 1992 06:09:35 GMT
Organization: Intel Corp., Chandler, Arizona
NNTP-Posting-Host: alfalfa.intel.com

In article <1992Nov9.005834.19898@murdoch.acc.Virginia.EDU> crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:
>     Which side do you want to take:  'Cooking' or 'Linguistics'?

You're blithering every time you iterate this soundly
disproved claim that science and religion are utterly
orthogonal in their philosophies and methodologies;
perhaps you could at least come up with two topics
that really are orthogonal, or are you going to claim
that religion and physics are the only two which are?

It's downright silly, it is.

>      Religion hardly has an axiomatic basis

Horseshit.

It begins with the base postulate that a diety exists.  There
is no religion that lacks this epitome of all axioms.

Here you depart from all semblance of reason, and I
will not humor your tragic little delusion any more.

				--Blair
				  "I have laundry to do, or
				   something dignified like that."
Newsgroups: sci.physics