HDTenEightyP/NetNews huggingface dataset:
From: gilligan@bldrdoc.gov (Jonathan M. Gilligan)
Newsgroups: sci.physics,sci.math
Subject: Re: Report on Philosophies of Physicists
Date: 14 Sep 92 23:52:51 GMT
Followup-To: sci.physics
Organization: National Institute of Standards and Technology

In article <1992Sep12.022132.4581@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
>But then I wonder, what is the point of Platonism?  Is it a sort of
>religion from which one derives comfort in the thought that out there
>somewhere is a reality, regardless of whether one's adopted axioms
>happen to be false of that reality?  I guess I can see that, but I sure
>don't need it for myself.  (Now why do I have this feeling that
>lightning could strike me for saying that? :-)

This is certainly what I think Kant was getting at in the Critique of
Pure Reason, when he discussed noumena. Also, it seems consistent with
his saying (I don't remember where right now) that he set limits on
reason to make room for God.

However, I think that it's a bit hard on old Plato to say that the
Republic and the Timeus represent the acme of his thought. In Phaedo,
probably his greatest work, he paints a far different picture in which
the search for truth is described metaphorically as sinking pilings
into mud to support an edifice.  You sink the piling so deep and it
will support the edifice you want to erect.  If later you want to add
to the edifice and the pilings won't support the added weight, you
have to sink new pilings deeper into the ground. However, at the end
Socrates dies without ever having hit bedrock.

In contrast to the sad and restrained tone of Phaedo, the Republic
seems a bit of a party game---a parody of the torch race that precedes
the dialogue.

---Jon

-- 

Disclaimer --- The government probably disagrees with my opinions.
Newsgroups: sci.physics
From: chrism@col.hp.com (Chris Magnuson)
Subject: HELP: "Tipler" PHYSICS Textbook
Date: Thu, 10 Sep 1992 17:17:50 GMT
Organization: HP Colorado Springs Division

I am in need of the answer book for the Tipler "Physics" book, Second Edition.
This book is old (I used it 6 years ago in undergraduate school) and I need the
answerbook to help me prepare for an upcoming entrance exam.

If you have a copy of the answer book you could give or sell, please contact me.

Chris Magnuson 
chrism@col.hp.com
(719) 590-2963 W  (719) 481-9271 H 
Newsgroups: sci.physics
From: cannon@scs.unt.edu (Dustin Cannon (Lab 3460))
Subject: Quantitization of Length
Organization: School of Community Service, UNT
Date: Sat, 12 Sep 1992 19:57:12 GMT


	Thanks for all you posts.  It gave me alot of stuff to chew over.  
Now I can take Quantum in the Spring with an arsenal of questions for my 
prof.
_________________________________________________________________
Dustin W. Cannon      "Just because some of us can read and write
University of          and do a little math, that doesn't mean we
North Texas            deserve to conquer the universe."
                                                -Kurt Vonnegut
Newsgroups: sci.physics
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Subject: Re: BAROMETERS (was Re: Subject?)
Organization: Intel Corp., Chandler, Arizona
Distribution: na
Date: Tue, 8 Sep 1992 16:11:46 GMT

In article <mcirvin.715918669@husc8> mcirvin@husc8.harvard.edu (Mcirvin) writes:
>bhoughto@sedona.intel.com (Blair P. Houghton) writes:
>>Which begs the question:  How tall was Torr?
>That's Torricelli.

1.  Hang barometer from short string.

2.  Swing sharply backward over one shoulder.

3.  Repeat.

				--Blair
				  "I hate confession..."
Newsgroups: sci.physics,sci.astro
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: VLBI (was: My son would like to know about photons...)
News-Software: VAX/VMS VNEWS 1.41    
Keywords: photon,size
Organization: Texas A&M University, Academic Computing Services
Date: Tue, 8 Sep 1992 19:44:00 GMT

mcirvin@husc8.harvard.edu (Mcirvin) writes...
>>Hmmm. When I was an undergrad I worked in the Caltech VLBI Processing unit.
>>We plugged around 8 hours of data taken from radio telescopes around the
>>world into the computer. The data was stored on VCR tapes. Since we were
>>measuring interference, I always wondered how the phase information could
>>be stored on a VCR tape. I would have thought each photon would go into
>>one antenna or the other. Any astrophysicists out there?
>
>[deletia]
>The processes that create strong classical electromagnetic waves are
>exactly those that produce something very close to a coherent 
>state of photons, since a coherent state is the closest thing to
>a classical EM wave that really exists.  Oscillating currents in
>a transmitting antenna, for instance, will produce nearly
>coherent photons, and so, presumably, would the oscillating
>currents involved in whatever astrophysical phenomena are being
>imaged.

I think I understand this explanation, except that I don't see why separate
photons should be correlated since in cases of interest the measured
radiation is thermal.

Dave Ring
dwr2560@zeus.tamu.edu









Newsgroups: sci.physics
From: jcf@world.std.com (Joseph C Fineman)
Subject: Air bubbles in water (bis)
Summary: A reply to an earlier question about the gravitational interaction
Keywords: gravity, hydrostatics, bubble, unphysicality
Organization: The World Public Access UNIX, Brookline, MA
Date: Thu, 10 Sep 1992 01:52:21 GMT

I have not seen a reply to the following inquiry:

>Sat, 1 Aug 1992
>Noam Bernstein: Air bubbles in water
>We came across a problem a few days ago when a frosh here asked us about
>it.  First consider two spheres of water (in zero G), in an infinitely
>big container.  Because of gravity, they attract.  Now, consider two
>spherical air bubbles in an infinite volume of water (0 G, again).  Now,
>which way do the bubbles move (if at all) ?
>After a long discussion (which involved some of the participants switching
>sides several times), we've convinced ourselves of what the right answer is
>(we think), but we want to see what you people think about it.
>                                                        Noam
>                                            noamb@egg.gg.caltech.edu

Consider first the case of a *finite* volume of water; for simplicity
(& to avoid the expense of a container), let it be spherical.  In
general, there will be buoyant forces on the bubbles; to minimize
these, place the midpoint of the pair of bubbles at the center of the
sphere.  Then the buoyant forces are in opposite directions, and the
bubbles will separate.  The gravitational field, and therefore the
buoyant force, at each bubble is somewhat lessened by the presence of
the other; in that modest sense they may be said to attract each
other, but still they separate.  This will continue to be true as the
sphere is made larger.  The putative limiting case where the sphere
fills all space and the buoyant force is 0 by symmetry is unreal.  It
is of course just as legitimate to make the body of water go to
infinity in an asymmetrical manner; in that case the buoyant forces
may become arbitrarily large, but in no case are they negligible.

[In general, the limit of "an infinite volume" of matter is
notoriously unphysical & must be approached with caution.  In
particular, the gravitational field is indeterminate: one may apply
Gauss's law to a sphere of chosen size & orientation and get any
answer one pleases.  Likewise, in hydrodynamical problems the integral
for the momentum is often not absolutely convergent, so that its value
depends on how one sweeps thru space during the integration.  It is
especially dangerous to combine spatial infinity with
incompressibility (as is tacitly done here), because that makes the
speed of sound infinite and allows momentum to disappear from the
visible universe instantaneously.]

I conclude that this is a nonsense question.  Nevertheless, I think
the frosh who asked it should have been named.

			Joe (Caltech '58, Ph, F)
			jcf@world.std.com
From: bradshaw@ccvax.ucd.ie
Newsgroups: sci.physics
Subject: Melting Point of YBCO "Green Phase"
Date: 6 Sep 92 14:37:55 GMT
Organization: University College Dublin

I have a question for anyone involved in superconductivity.....
Can anyone reading this tell me the melting point of the
semi-conducting "Green Phase" of YBCO? Any and all replies
appreciated. My E-Mail addresses are below. Thanks in advance...

My E-Mail addresses:

CBRADH89@IRLEARN.UCD.IE
BRADSHAW@CCVAX.UCD.IE
Newsgroups: sci.physics
From: raicu@netcom.com (Eugen Raicu)
Subject: Re: Why Do Mirrors Reverse Left/Right and Not Up/Down?
Date: Sat, 05 Sep 92 06:05:59 GMT
Organization: Netcom - Online Communication Services  (408 241-9760 guest) 
Distribution: na
X-Newsreader: Tin 1.1 PL4

You might also want to include a reference to First Scientific
American Book of Mathematical Puzzles and Diversions by Martin
Gardner, chapter 16.
-- 
Eugen Raicu
raicu@netcom.com
Newsgroups: sci.physics
From: abbasi@star.enet.dec.com (My name is Nasser ABBASI)
Subject: Re: Quantitized Length
Organization: Digital Equipment Corporation
Date: Mon, 7 Sep 1992 01:58:48 GMT


In article <cannon.7.715829635@scs.unt.edu>, cannon@scs.unt.edu (Dustin Cannon (Lab 3460)) writes...
>	I have a question.  I was thinking about the problem of the man 
>walking across a bridge, but he first walks half the distance and then can 
>only walk half the remaining distance and so on.  He never gets to the end, 
>right? 
>	Well, I was thinking that if length was quantitized just like 
>charge.  Then the man would get to a point were he simply could no longer 
>walk half the distance because he would be halving a quanta of length.
>	I liked this because it also solves a rather disturbing idea one of 
>my professors once said, which was that as two point charges come in contact 
>with each other they have infinte potential energy due to 1/r.  This, he 
>said, was in his mind a proof of God's exsistence.
>...

I'll try to show that we can look at the problem without the need to require
quantum length , Iam not sure if this way is an answer to your question or not.

looking at distance of each step as one entry in a sequence, we say that

        i=oo
        ---
        \  d_i   = total distance
        /
        ---
        i=1

we only need to know that the limit exist, and that the limit equals the
total distance to be covered.
we know the limit exist by the ratio test. (i.e series is convergent)
to know what is the limit is harder, but I'll fudge here and say that there
can be no other limit as number of steps goes to INFINITY other than
the length of the bridge.

now, as number of steps becomes smaller, the time to make each steps
becomes smaller also, since distance to cover is small, hence we'll
have , 

                                     i=oo
                                    ---
time taken to cross the bridge is   \ t_i 
                                    /
                                    --- 
                                    i=1

assuming person is walking in constant speed.

where t_i is time taken to make step i.
the above is convergent by ratio test. hence even though there are 
infinite number of steps, the time to cross the bridge is finite.

the reason for writing the above is to show that we can overcome the
problem without resorting to quantum of length. and hence the need for
quantum length is absent.

/Nasser

Newsgroups: sci.physics
From: terry@aslws01.asl.dl.nec.com (Terry Bollinger)
Subject: Did electric/magnetic symmetry "break"?
Organization: Bollinger Dumb Questions, Amalgamated
Date: Sat, 5 Sep 1992 07:35:28 GMT

Premises:

 o  If you ignore interactions with electrically chaged matter, electric
    and magnetic fields behave very similarly.

 o  However, they are highly assymmetrical in their relationship towards
    matter.  E.g., the electric field has associated with it two particles
    (among others) called the electron and positron, with opposite charges
    of (say) 1 unit each.  The equivalent particles for the magnetic field,
    if they exist at all, would have to have charges with magnitudes about
    63 times as great.

Dumb Question for Group Theorist Types:

 o  Can the assymmetry of [electric:1] and [magnetic:63] be defined
    mathematically as a "broken symmetry" -- that is, that at some time
    very early in the history of the universe *either* of the two fields
    could have been associated with charges of one unit, with the other
    one being relegated off to the lesser role of what we now call the
    "magnetic" field?

    If so, at what point in the development of the universe would this
    symmetry have been broken?

				Cheers,
				Terry Bollinger

Newsgroups: sci.physics,sci.math
From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
Subject: Re: Report on Philosophies of Physicists
Organization: Computer Science Department,  Stanford University.
Date: Mon, 14 Sep 1992 00:54:48 GMT

In article <TORKEL.92Sep14001401@bast.sics.se> torkel@sics.se (Torkel Franzen) writes:
>
>  I don't find in these remarks any explanation of why you refer to
>arbitrary (?) extensions of ZFC as different "foundations for mathematics".
>What mathematics is such an extension a foundation for, and in what sense is
>it a foundation?

You keep asking this question and I keep answering it and now I'm not
sure what you want in the answer because your question sounds the same
to me each time you ask it.  One more try before I give up.

(You can stop after the first "no" to these questions, since that will
bring us closer to the source of the disagreement.)  Matthew Wiener
asserted earlier today that physicists could safely base their
mathematics on PA.  (I've omitted RH to simplify this thread.)  Is that
a foundation as you understand the term?  Now add enough to bring this
up to ZFC.  Is this extension of PA a foundation?  Now add CH.  Is that
a foundation?  Are these three foundations different foundations?  Now
add some famous undecided but natural-sounding proposition in group
theory to ZFC.  Is that a foundation?  Is ZFC+# a foundation?  (Just
checking :-)

>  Your remaining remarks are quite irrelevant in so far as they refer
>to Godel codings. We may as well assume that the statement at issue is
>a statement of the form "the Diophantine equation ... has at least one
>solution".  As for such a statement being "true in" a theory in which
>it has been added as an axiom, of what relevance is this to my mathematical
>concern with the the solvability of Diophantine equations?

My remarks about Goedel codings were *highly* relevant until just now
when you changed your example from the very grubby Goedel-coded
sentence # to an unspecified Diophantine one.  (To keep a cowboy
hopping you have to shoot at both his feet alternately.)  Maybe your
sentence is cleaner, but I'll reserve judgement on that until you
produce it---there exist Diophantine sentences much more disgusting
than #, I hope you don't have any of *them* in mind.

Meanwhile, now my answer is much much easier than with #.  I have no
reason to suppose that the satisfiability of a random Diophantine
equation is independent of ZFC, so I'm certainly not going to waste my
time doing mathematics under the assumption that it is satisfiable.  A
subsequent proof of its unsatisfiability is quite on the cards, and
that would then put my little foundations completely out of business.

-- 
======================================================| God found the positive
Vaughan Pratt   pratt@cs.Stanford.EDU   415-494-2545  | integers, zero was
======================================================| there when He arrived.
Newsgroups: sci.physics,sci.math
From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
Subject: Re: Report on Philosophies of Physicists
Organization: Computer Science Department,  Stanford University.
Date: Thu, 10 Sep 1992 03:46:27 GMT

In article <22218@galaxy.ucr.edu> baez@ucrmath.ucr.edu (john baez) writes:
>In article <1223@kepler1.rentec.com> andrew@rentec.com (Andrew Mullhaupt) writes:
>>In other words, I defy anyone to make sensible the claim that mathematics is
>>_not_ a soft, warm fuzzy, human frailty. 
>
>Mathematics is clearly a human activity and as such subject to all the foibles
>of any other human activity, but it is NOT warm and fuzzy.  It is cool and
>smooth.  If you want something warm and fuzzy, raise koala bears.

Mathematics is smooth?  I'll have whatever you're smoking.  Whose
mathematics?  If ZFC, that's an r.e.-complete theory and hence not just
fuzzy but chaotic.  If first order number theory, that's the whole
arithmetic hierarchy and hence wildly chaotic.  If second order
logic...you get the drift.  The only smooth mathematics is polynomial
time algorithms, and even there you have to break out the dramamine at
around n^5.

With regard to temperature, the government agencies, bless them, prefer
to fund what's hot.  Mathematics is terrifically hot, for which it
deserves better recognition in Washington.

Today we all firmly believe that mathematics is a human activity.  St.
Augustine exposed mathematics as the work of the devil (how did he ever
find out), who then took centuries to live this down.

Mathematics is neither a cool and smooth nor warm and fuzzy human
activity but the hot and chaotic work of the devil.  Quayle needn't
know this.

-- 
======================================================| God found the positive
Vaughan Pratt   pratt@cs.Stanford.EDU   415-494-2545  | integers, zero was
======================================================| there when He arrived.
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Uncertainty Principle [T.Bollinger => LONG]
Date: 6 Sep 92 03:36:27 GMT
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: na
Reply-To: sichase@csa2.lbl.gov
NNTP-Posting-Host: 128.3.254.197
News-Software: VAX/VMS VNEWS 1.3-4   

In article <1992Sep5.170329.9152@galois.mit.edu>, jbaez@riesz.mit.edu (John C. Baez) writes...

>A rather odd sentence, that, but I get your drift.  :-)  Another victim
>of the lure of quantum quackery (in my humble opinion) is Josephson, the
>Nobelist of "Josephson junction" fame - whose circuits use sneaky
>quantum tricks closely related to the Bohm-Aharanov effect.  Check out
>his letter to the editor in the August (?) "Physics Today" in which he
>defends Jahn's research on telekinesis!

As a consequence of a short stint that I did as an undergrad in the MIT 
Superconducting Materials Lab, I knew two people who had known Josephson,
at least as far as spending an afternoon or more with him on some occasion.
The mutual opinion of these two profs was that Josephson had won his glory too 
soon (he was very young when he won his Nobel prize) and couldn't handle it.
He was arrogant to the point of incredible rudeness.  He had to have his
way on the littlest things, like refusing not to light up his stogie in the 
office of a proffessor who was very picky about smoke.  He behaves as if he 
thinks that he is far more brilliant than you can possibly even begin to 
imagine.  (These are my words, not my source's.  It's been too long to 
remember exactly whatI was told.)

Given this emotional state, and finding himself unable to recapture past 
successes, it does not surprise me that he has become so eccentric.

-Scott

--------------------
Scott I. Chase			"The question seems to be of such a character
SICHASE@CSA2.LBL.GOV		that if I should come to life after my death
				and some mathematician were to tell me that it
				had been definitely settled, I think I would
				immediately drop dead again."      - Vandiver
Newsgroups: sci.physics
From: clarke@acme.ucf.edu (Thomas Clarke)
Subject: Re: Society's New Contract with Scientists (draft legislation)
Organization: University of Central Florida
Date: Mon, 14 Sep 1992 14:34:46 GMT

In article <iXuZqB2w165w@netlink.cts.com>  writes:
> The following draft legislation proposes a new contract with 
> scientists in which their funding is guided by society's needs,
> and which avoids the historical failure mode of institutions
> such as NASA by linking funding authority NOT to the position
> one attains within a bureaucracy, but rather to the actual
> contributions one has made to valuable technologies as measured
> by one's contribution to total patent royalties.
> ...
>         (9) Our country was founded by scientists and technologists who
> placed within our Constitution prohibitions against patents of nobility 
> at the same time as they provided for patents of invention.
>  
>         (10) United States culture is based on the recognized nobility of
> the creative act, rather than mere possession of property or inheritance.
>  
>....
>         (c) ASSIGN AUTHORITY -- In cooperation with the Internal Revenue
> Service, the Administrator shall assign a funding authority level to 
> all Authorizing Inventors, which is the percent of total Authorizing 
> Royalties each Authorizing Inventor's total Authorizing Inventions 
> are responsible for, multiplied by the total amount of funding 
> appropriated for scientific research by Congress.
>  
Sounds good to me!  Where do I sign up?
Since I am that somewhat rare bird, a publishing, grant writing
scientist who also hold patents, would I be able to become
an Authorizing Inventor and fund my own research? :-)
--
Thomas Clarke
Institute for Simulation and Training, University of Central FL
12424 Research Parkway, Suite 300, Orlando, FL 32826
(407)658-5030, FAX: (407)658-5059, clarke@acme.ucf.edu
From: chem@uwpg02.uwinnipeg.ca
Newsgroups: sci.physics
Subject: Physics Educators Macintosh FTP site?
Date: 13 Sep 92 18:39:58 GMT
Organization: University of Winnipeg

Hi. What is the address of the anonymous FTP site
for Macintosh programs of the Physics Educators Mac user
group (based in Kalamazoo; David Winch ? and Cathy ? are
some of the organizors).  THis info was given in the most
recent newsletter which I lost upon moving to a new house.
Can anyone give me this info.  E-mail directly to me and thanks
very much.  Sincerely, Marshall Carroll

Internet:  CHEM@UWPG02.UWINNIPEG.CA
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Newsgroups: sci.physics
Subject: What do we know or believe about generations?
Date: 11 Sep 92 02:04:09 GMT
Organization: National University of Singapore

One of the really pressing problems in physics is the generation
problem: why do we have three?
What solutions have been proposed for this one?
I know one: in string theory, the CAlabi-Yau people proposed that we
have more than one generation essentially because of the way that the
topology of the internal manifold affects the solutions of the Dirac
equation. The number of generations turns out to be related to the Euler
characteristic of the internal space. This extremely natural solution of
the problem seems to be dying out along with string theory itself.
What other solutions have been proposed?
Newsgroups: sci.physics
From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
Subject: Re: Size of neutrino
Organization: Computer Science Department,  Stanford University.
Date: Tue, 15 Sep 1992 14:30:24 GMT

In article <1992Sep15.064618.6423@midway.uchicago.edu> mfm0@midway.uchicago.edu writes:
>I seem to remember a upper bound on the size of an electron,
>a statement like "we know that an electron is smaller than
>10^-x cm in diameter.

Then you have the corresponding lower bound on its momentum.  There is
no a priori reason I know of to place any lower bound on the momentum
of an electron.

Or does the phase velocity / group velocity distinction somehow enter
into the story in order to distinguish "size" from "uncertainty in
position"?  Are fermions such as electrons any more "concrete" than
bosons such as photons, in regard to the size question?  I rather doubt
it but I'm in the process of trying to grasp this stuff myself just now
and I still feel shaky about getting an electron out of Dirac's
equation.

-- 
======================================================| God found the positive
Vaughan Pratt   pratt@cs.Stanford.EDU   415-494-2545  | integers, zero was
======================================================| there when He arrived.
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: gravity/height
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Wed, 16 Sep 92 01:34:10 GMT


Ack.   I meant, if 2hW/r is a lot bigger than P!
>
>