HDTenEightyP/NetNews huggingface dataset:
From: mporter@nyx.cs.du.edu (Mitchell Porter)
Subject: John Baez / sci.physics archives
Organization: Nyx, Public Access Unix @ U. of Denver Math/CS dept.
Date: Wed, 11 Nov 92 03:27:50 GMT

I would like to see John Baez's expository postings archived somewhere -
and for that matter, anything of a similar nature that might be posted
here (Alexander Abian's instant introduction to diffeomorphisms, etc?). I
think it would be a good idea to have an ftp site somewhere which would
contain introductions to interesting and/or important concepts, and
perhaps the FAQ list as well.
(I don't know  if JB has retained copies of all the expositions he's
posted; I only have a few.)

Newsgroups: sci.physics,sci.math
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: graphical humping terminology
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Wed, 11 Nov 92 20:23:18 GMT

In article <1992Nov11.063332.22820@galois.mit.edu> jbaez@riesz.mit.edu (John C. Baez) writes:

>Gaussians are very useful but pretending that every
>molehill or mountain is a Gaussian can lead to lots of errors - so it's
>good that mathematicians have a technical term for the kind of function
>you are referring to.  It's called a "bump function", or "bump".

The "bump functions" mathematicians use are usually C_0^\infty, that is,
infinitely differentiable and compactly supported.  If for some reason
one wants to reserve the term bump for C_0^\infty functions, one could
call more general functions "lumps" or "humps".  It might be nice to
have all 3 of these become technical terms.

Thm.  The product of two lumps is a hump.

etc. would be fun to see.

Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Justification for Research (was: Re: Particle Research)
Organization: MIT Department of Mathematics, Cambridge, LA
Date: Fri, 13 Nov 92 21:10:38 GMT

In article <1dsf8tINNc9p@terminator.rs.itd.umich.edu> metzler@pablo.physics.lsa.umich.edu (Chris Metzler) writes:
>
>This newsgroup is busy lately.
>
>I wrote, in reply to Scott Chase . . .
>
>> Bravo, Scott.  You have hit upon what I consider to be the core issue of
>> supporting basic, pure scientific research.  I believe that in some sense,
>> we must consider learning simply for learning's sake to be worthwhile.
>> I work in theoretical cosmology -- specifically, the theory of large-scale
>> strucutre -- which is probably one of the least practically useful fields
>> of physics.  I believe that the justification for funding my research
>> is a lot like the justification for being patrons of painters or poets.
>
>and John Baez replied . . .
>
>> I hope, then, that you will satisfied with a level of government funding
>> of science comparable to that received by painters and poets.  This means
>> either a massive increase in government support of the arts, a massive
>> decrease in government funding of pure scientific research, or something
>> in between.  
>
>I have to say, John, that I don't follow you here.  If I remember correctly,
>you work in mathematical aspects of quantum gravity.  Is this indeed the case?
>If so, I would say that you too work in a field that's not very practically
>useful.  Nonetheless, I'd say that it's still worth support, because I do
>believe that understanding is its own justification. 

Yes, I work in quantum gravity.  Yes, it's not very practically useful
yet.  But the very amusing and revealing aspect of your post is that you
simply ASSUME that I believe that my work deserves government funding!!
In fact, I don't.  




Xref: sparky sci.physics:18418 sci.chem:4473 sci.engr.chem:558
From: kgrossha@radford.vak12ed.edu (Kurt Grosshans)
Newsgroups: sci.physics,sci.chem,sci.engr.chem
Subject: Re: Specific Heat
Date: 8 Nov 92 18:40:22 GMT
Distribution: usa
Organization: Virginia's Public Education Network (Radford)

jerry@wshb.csms.com  writes:
> 
> I am trying to find what metals have these specific heats:
> 
>    1) 2740 joules/kg deg.C
>    2)  848.6 joules/kg deg.C
> 
> Please replay E-mail: jerry@wshb.csms.com
> 
> Thanks in advance.
> -- 
>                       Jerry Lopez--Broadcast Engineer 
>                 WSHB - An International Broadcast Station of   
>            Herald Broadcasting Syn., Inc., Cypress Creek, SC, USA
>                             jerry@wshb.csms.com

Am I crazy, or are his units off for numbers of that magnitude?
-- 
=-=-=-=-=-=-=-=-=-==-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-==-=-=-=-=
Kurt Grosshans
kgrossha@radford.vak12ed.edu
From: ramsay@unixg.ubc.ca (Keith Ramsay)
Newsgroups: sci.physics
Subject: Re: Sarfatti Stuff FTL QM Connection Signal
Date: 9 Nov 1992 00:02:12 GMT
Organization: University of British Columbia, Vancouver, B.C., Canada
NNTP-Posting-Host: unixg.ubc.ca


Just one simple question, Sarfatti:

Are you claiming that, according to standard quantum mechanics, it is
possible for there to be two (pure) states represented by |f> and |g>,
which are orthogonal, and an observation which can be performed, which
has the property that both |f> and |g> will reliably be collapsed into
a single state |h> by performing that observation? Let |h> be pure or
mixed-- whatever you like. Let us just be clear: are you claiming that
this is consistent with standard quantum mechanics?

Keith Ramsay
ramsay@unixg.ubc.ca
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Newsgroups: sci.physics
Subject: Re: Religion & Physics Don't Mix
Date: 10 Nov 92 00:45:33 GMT
Organization: Intel Corp., Chandler, Arizona
NNTP-Posting-Host: alfalfa.intel.com

In article <1dmd58INNr1b@morrow.stanford.edu> mihai@sep.Stanford.EDU (Alexander Mihai Popovici) writes:
>Einstein said once that he believes God is a mathematician of
>a higher order.

There's a book called _Quantum_Questions_ that collects essays,
by Einstein and others, that study the very sort of difficulty
this (mootly named) thread addresses.

				--Blair
				  "Corky Bass sews socks in hell"
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: The size of electrons, and Fanciful misc SAGA
Date: 5 Nov 92 23:26:41 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

dave@prim.demon.co.uk (Dave Griffiths) writes:
>>  ... 
>>This is not a statement of any physics that *I* know.  As a matter of fact,
>>I'm willing to go further and say that it's total rubbish.  Can you 
>>point to a textbook which contains any statement resembling what you have
>>claimed?

>Think for yourself! I've no idea what he was talking about either, but just
>because it's not in a textbook doesn't make it rubbish.

You have no idea, Scott has no idea, I have no idea.  When someone
tells me about wild and crazy physics (eg renormaliztion, inflationary
cosmology, etc.), and I have no idea what he/she's talking about, I
try to go and find a textbook to learn more about the subject (instead
of just posting inanity to Usenet, OK?)  On the other hand I don't
imagine I'll do that this time, 'cause my bullshit detector is going off.

>Well if it's textbooks you're into, you might try Feynman's Lectures Vol II,
>chapter 28 where he describes how the theory of electromagnetism, even
>modified by QM, "ultimately falls flat on it's face" owing to the infinite
>field energy of a point charge.

See "renormalization," above.  This may surprise you, but the Feynman
Lectures do not cover ALL of physics.
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Religion & Physics Don't Mix
Date: 6 Nov 92 16:47:11 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

mhorning@zeus.calpoly.edu (Mark E. Horning (Captain Neutrino)) writes:
>No, no. You have to treat science as an approximation. As information
>goes towards infinity, science goes towards reality. Therefore whe it 
>changes it more closely approximates the truth.
 
I should keep my mouth shut, but here goes.  The concept of science
as a series of successive approximations to some "truth" (of nature,
or whatever) is fatally flawed.  Let's trot out a couple of hoary
examples.  Does one consider general relativity to be a "second-order
correction" to Newtonian gravity, an extra term in the series of truth?
Well, in the post-Newtonian approximation, it is literally a bunch of
higher-order terms, but that seems to me to miss the point.  I would
argue that general relativity is a fundamentally different world-view
from Newtonian gravity, and should be seen as not just "closer to the
truth," but as a radical reformulation of our assumptions about the
world.  One could say similar things about quantum mechanics, especially
in e.g. the theory of metals (conductivity, etc.).  Similarly for
concepts of inheritance before and after the acceptance of Mendel ...
From: matt@physics3.berkeley.edu (Matt Austern)
Newsgroups: sci.physics
Subject: Re: No big crunch?
Date: 6 Nov 92 13:47:43
Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
	<1992Nov5.212050.25373@murdoch.acc.Virginia.EDU>
	<6NOV199211570602@csa1.lbl.gov>
	<1992Nov6.201950.26221@murdoch.acc.Virginia.EDU>
Reply-To: matt@physics.berkeley.edu
NNTP-Posting-Host: physics3.berkeley.edu
In-reply-to: crb7q@kelvin.seas.Virginia.EDU's message of Fri, 6 Nov 1992 20:19:50 GMT

In article <1992Nov6.201950.26221@murdoch.acc.Virginia.EDU> crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:

>      Hindsight may well be deceiving you.
> 
>      I await with interest the discovery of the Higgs' boson.

Oh, I agree with Scott that consistency is a powerful tool for telling
that a model might be correct.  (Surprisingly few models pass this
test, and it isn't in the least trivial.)

So, along those lines, you should be aware that there are a great many
people who think that a theory with a Higgs boson in it might not be
self-consistent.  The argument along these lines is called
"triviality."

These arguments aren't completely solid, and, even if they are
actually true, something that looks like a Higgs might exist; it just
might not be a fundamental particle.

Still, the point is that not everyone believes in a Higgs boson.  (I'm
one of the people who is rather skeptical.)  It is quite certain that
there is *some* new physics below or at the 1 TeV scale, and that it
has something to do with electroweak symmetry breaking, but the Higgs
boson is only one of the possibilities---and not necessarily the most
plausible one.
--
Matthew Austern                   Just keep yelling until you attract a
(510) 644-2618                    crowd, then a constituency, a movement, a
austern@lbl.bitnet                faction, an army!  If you don't have any
matt@physics.berkeley.edu         solutions, become a part of the problem!
Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: Some physics questions
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Wed, 11 Nov 1992 21:30:00 GMT

sciamanda@edinboro.edu writes...
>> 4) Why is the speed of light constant?
>Short answer:  The invariance of c is an axiom of Einstein's special theory 
>of relativity (1905).
> 
>Long answer:  This question is really concerned with the matter of how we 
>choose (or design) standards for the measurement of space and time intervals.
[deletia]

Good answer. After some thought, I think the ultimate reason we can have
unambiguous standards for time is that the gravitational force is weak. In
particular, if it were impossible to make a clock whose size was small
compared to the scale of spacetime curvature, there could not be an
unambiguous standard.

Dave Ring
dwr2560@zeus.tamu.edu
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Solid-state doesn't use QED! (Was Re: Particle Research)
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Fri, 6 Nov 92 23:32:19 GMT

In article <BxA2GC.6yE@wsrcc.com> alison@wsrcc.com (Alison Chaiken) writes:

>As far as the theory of the electron goes, QED has had
>no impact on solid-state physics whatsoever.  I have been a
>solid-state physicist for 10 years, and I have never never seen or
>heard a single reference to QED corrections to electron energy levels.

That's nice to hear from a real solid state physicist - I'd
occaisionally wondered. 

>Having said all that, the theories of broken symmetry and elementary
>excitations (Goldstone bosons) in solid-state physics have been heavily
>influenced by particle theories.  Here solid-state is using the
>_concepts_ of field theory, not the results!  My understanding is that
>particle theories have been in turn influenced by solid-state theories
>(e.g., non-perturbative field theories are greatly influenced by the
>BCS theory of superconductivity).

Yes, here there seems to be a very nice interplay.  It's one of the few
things that keeps physicists talking to each other, the mathematical
analogies between condensed matter physics and field theory.  All sorts
of tricks, like the ones you mention and also renormalization group
methods, solitons and instantons, etc., show up in both subjects.
Here's to the unity of nature!
Newsgroups: sci.physics,sci.math
From: news@massey.ac.nz (USENET News System)
Subject: Re: What's a manifold?
Organization: Massey University
Date: Thu, 5 Nov 92 23:57:09 GMT

In article <1992Nov5.161930.21320@CSD-NewsHost.Stanford.EDU>, pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
> 
> In article <SMITH.92Nov5101553@gramian.harvard.edu> smith@gramian.harvard.edu (Steven Smith) writes:
> >pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
> >
> This won't wash, you've just replaced one arbitrariness with another
> more complicated one, namely the notion of atlas.

An individual atlas may be arbitrary, but the manifold is not. A differentiable
manifold is defined as a set equipped with a COMPLETE atlas. That is
it contains every compatible chart.

One atlas is rather like a base for a topology - it describes the manifold
completely because there is only one completion just as a base for a
topology generates a unique topology.

> An ATLAS F on a
> topological space M is a family of CHARTS (fi,Ui) where the family <Ui>
> is an open cover of M and each fi:Ui->R^n is a homeomorphism from Ui to
> an open subset of R^n, such that the fi's of overlapping Ui's
> "coordinate smoothly" at the overlap.  A MANIFOLD is a pair (M,F)
> consisting of a topological space M and an atlas F on M.

You don't need to build homeomorphisms into the definition. The fi
define a topology such that they become homeomorphisms. There is
no real practical impact to this - either you define the topology first
and then define the manifold structure, or you define them simultaneously.
 
> 
> Furthermore my definition is a *lot* simpler, I'd say, even without
> going into the notion of smooth coordination required to define an
> atlas.
> 
> There has to be some other reason why the complicated notion of atlas
> is essential.

In what way is it complicated? A chart seems to be a very natural
expression of the idea of locally Euclidean.

Terry Moore
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Error in NO FTL Signal Proofs exposed.
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Fri, 13 Nov 92 21:32:02 GMT

In article <Nov.12.19.37.01.1992.405@ruhets.rutgers.edu> bweiner@ruhets.rutgers.edu (Benjamin Weiner) writes:
>firth@sei.cmu.edu (Robert Firth) writes:
>[re Sarfatti]
>>I'm not going to sound like a broken record, so this will be
>>absolutely my last contribution to the debate: please, somebody,
>>DO THE EXPERIMENT.  This issue will never be decided on the
>>basis of scripture, dogma, and anathema.  Only Nature knows;
>>go ask her.
>
>Look, Robert, you're not giving us credit.  The issue is not, (1) does 
>this method of FTL communication exist?  The issue is, (2) does
>orthodox QM imply this possibility?  
>
>(1) can only be tested by experiment, but no compelling reason has been
>given to believe it.  Unless you or anybody else is interested enough 
>to actually *fund* the experiment, it won't get done.
>
>On the other hand, (2) is possible to discuss mathematically.  The 
>problem is that Sarfatti evades all attempts to construct a rigorous
>description of his apparatus and calculations.  You seem to have a 
>good grasp of quantum mechanics - so can you tell us what he's talking
>about?

I already told Robert this.  Perhaps I wasn't sufficiently eloquent to
get my point across.  But let me just say that I agree completely with
Benjamin Weiner's point.  It makes perfect sense to argue about what can
or cannot happen according to orthodox QM without doing any experiments.
If Sarfatti claimed he had a NEW THEORY that contradicted orthodox QM
one would have to see if his theory was consistent and met experimental
tests.  But he seems to be claiming that orthodox QM predicts FTL
communication.  Of course, his way of doing orthodox QM looks very
unorthodox, i.e., wrong.
From: johno@sdd.hp.com (John Ongtooguk)
Newsgroups: sci.physics
Subject: Re: Religion & Physics Don't Mix
Date: 5 Nov 1992 18:13:52 GMT
Organization: Hewlett-Packard, San Diego Division
Distribution: world
NNTP-Posting-Host: hpsdlg10.sdd.hp.com

In article <1d9tejINNq6p@chnews.intel.com>, bhoughto@sedona.intel.com (Blair P. Houghton) writes:
|> 
|> Science is truth, and truth is science. They are one and the same. 

  If the truth is always changing then what is it after it changes ?

  John Ongtooguk (johno@sdd.hp.com)
From: mcrae@husc8.harvard.edu (Andrew McRae,   ,,)
Newsgroups: sci.physics
Subject: Re: Do Balloons fly?
Date: 5 Nov 92 20:45:19 GMT
Article-I.D.: husc3.1992Nov5.154520.17143
Reply-To: mcrae@husc8.harvard.edu
Originator: mcrae@husc8.harvard.edu

I've been out of physics since 1987, so don't be at all surprised if I
make some dumb mistakes in this post. But I'm sure _someone's_ got it
wrong, so here goes: 

In article <1dbs8vINNau0@agate.berkeley.edu>, aephraim@physics.Berkeley.EDU (Aephraim M. Steinberg) writes:
> In article <1992Nov5.130316.28438@kth.se> e92_anh@vaxkab.lne.kth.se () writes:
>>This will probably sound like a silly question to a lot of you, but WHY
>>does a helium-filled balloon rise upward? Is it because of the
>>difference in air-pressure at the balloon's top and bottom, causing the
>>resulting force to press it upward?
> 
> Yes, amazingly enough.
> 
>>Thus, consider this: If the air surrounding the balloon had exactly the
>>same density on all sides, then the balloon would not move (I think).
> 
> No, actually it would sink, I think, because there is still the effect
> of gravity.

Surely, surely not! We're talking about a standard helium-filled balloon,
aren't we, which is less dense than air. So consider a helium balloon in a
closed room with constant (to a close-enough approximation) pressure
throughout, so that the balloon's volume is independent of its position.
If the balloon rises, then some air falls to replace it, and the
gravitational potential energy of the system has decreased (because the
air is more massive than the balloon). Similarly, for the balloon to fall,
the GPE of the system would have to increase. So given that when a balloon
rises the released GPE is dissipated as heat in the system, the balloon's
ascent is thermodynamically irreversible (and can be driven e.g by thermal
motion of air molecules). Therefore, it seems to me that in the case of
uniform pressure, the gravitational field will still cause the balloon to
rise. 

The real-life case where there's a pressure gradient is trickier, because
one has to justify the claim that the air that falls is more massive than
the balloon allowing for them both changing volume during the process. But
consider a rigid hollow ball, with vacuum inside. This could function as a
balloon, being less massive than the air it displaces, and it won't change
volume -- the above account seems to work again, suggesting that it'll
work for everyday balloons (which don't seem to change volume much at all
in going from, say, ground level to 100ft). 

In sum, I'd have thought that the explanation for why balloons rise is the
same as that for why submarines rise when they blow their ballast tanks --
they're less dense than the surrounding medium, so when they rise the
medium sinks and gravitational potential energy is lost as heat.

Of course, if I've got it all wrong please don't hesitate to tell me so.

Andrew.
-- 
Andrew McRae                       Internet: mcrae@husc.harvard.edu
                                     BITnet: mcrae@HUSC
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: NASA Coverup
Keywords: More sources 43595 mile figure
Date: 8 Nov 92 22:40:28 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Organization: SCRI, Florida State University

In article <4601@cruzio.santa-cruz.ca.us> snarfy@cruzio.santa-cruz.ca.us writes:
>
>     I've been getting a lot of E-mail flak about my NASA coverup  postings.

>   2. The figures given by Time or Von Braun are typos or mistakes.
>
>   3. The figures given by Time or Von Braun confuse miles with kilometers.

The most likely explanation.  Calculation with the canonical values, 
which give the surface gravity of the moon to be about 1/6 that of 
earth, give the force balance point to be about 38,000 km from the 
center of the moon.  Since the spacecraft does not fly straight up 
to a stationary target, but rather leads it, the difference between 
38 and 43 could be due to having to take the actual trajectory into 
account in the calculation. 

The other possibility is that someone divided the distance to the moon by 6.

>   4. The  explanation  for  the  apparent  lack  of jumping ability of the
>     astronauts is that the suits were as heavy  as  claimed  ,  and  simple
>     judicious caution on their part prevented more spectacular leaping.

Not heavy, inflexible.  Remember, they are inflated in a vacuum and all 
joints must be airtight.  Not exactly the thing to perform gymnastics in; 
remember Shepards terrible golf swing?  Anyway, it is not the height but 
the length of time in flight that counts.  The time-to-height ratio tells 
you g, and that ratio was much longer (hence g lower) than on earth.

This is the best empirical evidence, along with the orbital period of 
the Apollo command module.  Quoting from articles in the popular press 
is not the same as objective scientific evidence.  The numbers about 
the command module orbit are out there, why don't you track them down
and give us a follow up report.  

>   I believe that the direct quotation from the July 25,1969  Time  magazine
>   article would be helpful here:
>
>   "At  a  point 43,495 from the moon, lunar gravity exerted a force [on the
>   spacecraft] equal to the gravity of the Earth , then some  200,000  miles
>   distant."

Well, the numbers do add up.  Which is not to say that the reporter got 
a value in kilometers, misunderstood it, then subtracted it from the 
distance to the moon to put the distances in perspective.  I would be 
more likely to trust numbers in a monograph by von Braun.  

>   In "Project Apollo: Man to the Moon" by Thomas J. Alexander  (Harper  and
>   Row , 1964 ) ,the author states:

This book is copyrighted back when we were still having trouble hitting 
the moon.  One might question its reliability.  It could also be the 
case that Time got its info from this book! 

--
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)