HDTenEightyP/NetNews huggingface dataset:
From: torkel@sics.se (Torkel Franzen)
Subject: Re: Report on Philosophies of Physicists
Organization: Swedish Institute of Computer Science, Kista
	<1992Sep13.174721.23818@CSD-NewsHost.Stanford.EDU>
	<TORKEL.92Sep13202910@bast.sics.se>
	<1992Sep13.211250.26056@CSD-NewsHost.Stanford.EDU>
Date: Sun, 13 Sep 1992 23:14:01 GMT

In article <1992Sep13.211250.26056@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.
Stanford.EDU (Vaughan R. Pratt) writes:

   >It's the same with ZFC, you can write it out highly formally, but you get
   >the idea better when you work with it informally (who wants to work
   >with a big mass of symbols?).  Likewise ZFC+V=L, or ZFC+CH, can be
   >written formally, but one tends to think about their respective
   >meanings informally.

  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?

  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?
Newsgroups: sci.physics
From: kim@Lise.Unit.NO (Kim Gunnar St|vring \yhus)
Subject: Re: Report on Philosophies of Physicists
Organization: Norwegian Institute of Technology
Date: Sat, 5 Sep 92 14:13:20 GMT

In article <2726@news.cerf.net>, mitsu@nic.cerf.net (Mitsuharu Hadeishi) writes:
 > kim@Lise.Unit.NO (Kim Gunnar St|vring yhus) writes:
 > >In article <2697@news.cerf.net>, mitsu@nic.cerf.net (Mitsuharu Hadeishi) writes:
 > >>barry@arnold.math.ucla.edu (Barry Merriman) writes:
 > >>>>...
 > >>>The above is all at the most metaphorical level. Is there any situation
 > >>>in the experience of the Eastern philosophers in which boolean logic 
 > >>>was strictly violated? .....
 > >> 
 > >>         It is very difficult to answer your question briefly,---
 > >
 > >(in other words, you don't know the answer.)
 > 
 > 	Well, yes, but then, who does?  :-)
 > 
Glibnes won't help you here, since you state immediatele below that it
is possible to fully answer, and to do that, one have to know the answer.
This confirm my suspicion that you just write a lot of empty words.

 > >>--since to fully answer it would require that you have studied a great
 > >>deal of Eastern philosophy.  The relevant questions lie along ....


The problem is, apart from referencing to Wittgenstein, you tell us
absolutely nothing about what you mean by 'eastern philosophies'.
You refuse to describe it. But why haven't you named it? Are you
talking about Zen-buddhism? Konfucius? Ying-Yang? Many people on the
net, including myself, have studied this, and have well founded opinions,
for and against.

              Kim 0yhus
Xref: sparky sci.physics:14621 sci.math:11408
From: weemba@sagi.wistar.upenn.edu (Matthew P Wiener)
Newsgroups: sci.physics,sci.math
Subject: Re: Applied inconsistency
Date: 14 Sep 92 13:56:50 GMT
Reply-To: weemba@sagi.wistar.upenn.edu (Matthew P Wiener)
Followup-To: sci.physics
Organization: The Wistar Institute of Anatomy and Biology
In-reply-to: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)

In article <1992Sep13.231858.27317@CSD-NewsHost.Stanford.EDU>, pratt@Sunburn (Vaughan R. Pratt) writes:
>>Do the physicists abandon ship?  Of course not.  They let the mathe-
>>maticians figure it out, and will continue to assume RH.  In essence
>>their TOE is modeled inside Large_Fragment(PA)+RH

>Whoa, that's a remarkably strong claim.

You misunderstood.  I was making no absolute claims, but presenting an
example.

>					  George Mackey's understanding
>of physics seems to involve Borel sets, is he completely alone in
>that?

Of course not.  In fact, that's just the beginning.  PRL has published a
paper that mentioned "Martin's Axiom".  IJTP has published stuff involving
Boolean-valued models.  And so on.

>       Anyway, if you want to understand Mackey you need to know about
>Borel sets.

Right.  If you want to understand Mackey.  If you want to understand the
real world, it's not so clear that you need to go beyond recursive analogs.
For one small example, it's a theorem that analytic number theory is, in
general, a conservative extension of PA.

>The belief that somehow physics will never need to venture anywhere
>near where mathematicians have been venturing has no rational basis.

That's absolutely correct.  Meanwhile, the operational content can be
modeled at a very low level.  Which is why, were physicists to enshrine,
based on experiment, a theory involving something that later turned out to
have a high-level and highly subtle (in a technical sense) inconsistency,
they could ignore it and leave it to the mathematicians to figure out how
to formalize their work.

Not that this is anything new.
-- 
-Matthew P Wiener (weemba@sagi.wistar.upenn.edu)
Newsgroups: sci.physics
From: malova@venus.iteb.serpukhov.su
Subject: Are redshifts discrete?
Organization: Institute of Theoretical and Experimental Biophysics
Date: Tue, 8 Sep 1992 22:15:44 GMT

   Some years ago I read about discrete distribution of redshifts. 
   What is now? Is the idea alive?
                       Valery Colombet
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Hidden variable theories, was: Uncertainty Princi
Date: 11 Sep 92 00:15:49 GMT
Article-I.D.: husc8.mcirvin.716170549

foxd@silver.ucs.indiana.edu (daniel fox) writes:

>What has bothered me about the "killing your grandfather time travel paradox"
>is that it seems to assume a Newtonian view of the universe.  I would think
>that if such an experiment were attempted (by using massive rotating cylinders
>or whatever) one would find that quantum mechanics would have to be used to
>figure out what happened.

[Beware!  The next two paragraphs are full of wild-eyed,
 totally unjustified speculation.]

That's certainly possible.  If the world evolves without wavefunction
collapse, you can treat everything as a path integral in some
configuration space, and you might (speaking *very* vaguely) be
able to imagine paths that make multiple passes through the same
stretch of time, visiting different configurations on each pass.

An alternative (which seems to me more likely) is to integrate
only over self-consistent configurations, where you don't prevent
your own birth or succeed in any similarly mischeivous action.  Time
paradoxes would simply not occur; the topology would eliminate 
large classes of possible histories.  This would be very odd.
The apparent arrow of time might behave very differently in the
vicinity of the region where the time loop occurs.  The would-be
murderous time traveler might witness seeming physical conspiracies 
to foil any attempts at grand-patricide.  This is the kind of thing
that science-fiction writers don't often use as a plot device 
because it seems like a cop-out! 

Causal quantum field theories have the comforting property that
they eliminate this kind of trouble in Minkowski spacetime.  But
you still might be able to build a time machine using a Tipler
cylinder, or wormholes, or all manner of things.  The obstructions
discovered to plague time machines made of cosmic strings have
led some to propose a general "Chronology Protection Conjecture"
that eliminates closed timelike lines, or hides them behind
event horizons; it's reminiscent of the Cosmic Censorship 
Conjecture, which does the same for singularities.  I don't think 
anybody has come up with a general physical justification for it. 
 
Here's another entry to the Questions
Without Known Answers List:  Is there some general obstruction to
setting up situations with closed timelike lines?  If so, what is it?
If not, how should we deal with them? 

-- 
Matt McIrvin, Cambridge, Massachusetts, USA 
Newsgroups: sci.physics
From: sawyer@utahep.uta.edu (Lee Sawyer)
Subject: And another thing (was Re: QUESTION: General Relativity)
News-Software: VAX/VMS VNEWS 1.41    
Organization: University of Texas at Arlington High Energy Physics Group
Date: Fri, 11 Sep 1992 19:11:00 GMT

In article <1992Sep8.213120.11935@linus.mitre.org>, m15133@mwvm.mitre.org (Graham K. Glover) writes...
>A question has come up in my considerations of relativity.  I would 
>appreciate any input anyone might have regarding it.
> 
>What happens to the frequency of a light wave that has been deflected by 
>the gravitational effects of a massive body?
> 
>    ------nu~0--->--\ nu~1
>                  *  \
>                 /    \
>    massive body      _\|
>                        nu~2
> 
>What is nu~1 and nu~2 relative to nu~0?  Why?  Please cite sources, if 
>possible.
> 
>----------------
>Graham K. Glover
>----------------

  Here is a related question , taken from a caller's question to Vig 
Teplitz (chrmn, Dept of Physics, SMU) during a Dallas public radio talk 
show :

  Does gravity bend different frequencies of light by different amounts,
and if it does is it possible to form an "Einstein Rainbow" ? (In
analogy to the recently seen Einstein Cross, which is formed by light
from a distant quasar being bent around an intermediate galaxy.) 

  I think I know the answer, but I would like to see the consensus
of the group before I venture my guess... 

       ================
         Lee Sawyer

         Dept of Physics
         Univ. of Texas
               at Arlington
Newsgroups: sci.physics
From: lbianchi@sol.yorku.ca ((Luigi M. Bianchi))
Subject: Re: What We Don't Know (YET!) (Was: Black hole + anti-Black hole = ?)
Organization: York University
Date: Thu, 10 Sep 1992 02:48:16 GMT

In article <26182@dog.ee.lbl.gov>, sichase@csa2.lbl.gov (SCOTT I CHASE) writes:
> In article <1992Sep9.052443.8026@galois.mit.edu>, jbaez@riesz.mit.edu (John C. Baez) writes...
>> 
>>It might be worth setting up a "we don't know list" for the physics FAQ.
>> 
> 

There is a rather beautiful collection of what we don't know in physics,
biology, chemistry and ecology: Ronald Duncan & Miranda Weston-Smith, eds.
_The Encyclopaedia of Ignorance_ (1978) Wallaby Books. (My copy is a paper-
back edition of the original, published by Pergamon Press in 1977.)
It is definitely out of date, but worth reading.  Just to give a sense of
the caliber of the collection, here are the names of some of the authors:
O.Frish, H.Bondi, J.A.Wheeler, T.Gold, A.Salam, R.Penrose,...

A list of what we don't know might even have the healthy effect of reducing
the size of our kill files.  I always start my courses with a couple of
lectures on our ignorance.  Too often we forget the difference between
speculations and currently accepted explanations.


-- 


	Luigi Bianchi

Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Did electric/magnetic symmetry "break"?
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Tue, 8 Sep 92 01:29:30 GMT

Well, my last post was a bit misleading although taken with McIrvin's
I think it should be clear.  In particular, my talk about an "artifact
of units" is a bit confusing, since units in which hbar = c = 1 are
pretty much god-given.  

So - 

The question "why are electric charges so much smaller than magnetic 
charges?" does make a certain amount of sense, I admit, but it is 
really just a curious way of asking, "why is the fine structure constant 
so much smaller than 1".   It's a rather weird to ask the question the
former way, since after all magnetic charges are (so far) just a
theoretical possibility.  Asking the question the latter way is
better, because you will find then that lots of people have
asked it already.  The answer still seems to be "nobody knows" -
despite the occasional string-theorist's claim to have a "theory of
everything"!  

Afficionados of those who plunged in where angels feared to tread will
have to check out Eddington's book in which he tried to "deduce" that
the fine structure constant was exactly 136.  Then it turned out to be
137 and he realized he'd left one something-or-other out.  Well, then
it turned out not to be exactly 137 either.  People can also try out
Irving Segal's article on the value of the fine structure constant. 
Sorry, I don't have the reference.  

Myself, I think 137.036 is just fine.  

Xref: sparky sci.physics:14638 sci.math:11428
From: holmes@opal.idbsu.edu (Randall Holmes)
Newsgroups: sci.physics,sci.math
Subject: Re: Report on Philosophies of Physicists
Date: 14 Sep 92 19:07:37 GMT
Organization: Boise State University Math Dept.

In article <1992Sep13.220940.4850@infodev.cam.ac.uk> gjm11@cus.cam.ac.uk (G.J. McCaughan) writes:
>In article <1992Sep13.045114.17931@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
>
>>was impressive given Koenig's very high reputation.)  A month later
>>Zermelo was able to prove Cantor's continuum hypothesis assuming the
>>Axiom of Choice,

This is an error.  Zermelo did not prove CH.  He proved the
well-ordering principle using AC (I'm looking at the same book).

 but despite the further uproar Zermelo's result
>>produced, the eventual upshot was more to call AC into question than to
>>resolve the continuum hypothesis.
>
>Are you sure about this? I mean, you don't say his proof was wrong or
>anything, but I'm completely certain that not(CH) is consistent with AC.
>In fact I can prove it. So errrm, do you mean that Zermelo was able to
>think (wrongly) that he had proved CH using AC? or are we talking about
>a radically different set theory to the one I'm thinking of? or what?
>-- 
>Gareth McCaughan     Dept. of Pure Mathematics & Mathematical Statistics,
>gjm11@cus.cam.ac.uk  Cambridge University, England.    [Research student]


-- 
The opinions expressed		|     --Sincerely,
above are not the "official"	|     M. Randall Holmes
opinions of any person		|     Math. Dept., Boise State Univ.
or institution.			|     holmes@opal.idbsu.edu
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: It's Down to the Last Blank Check
Date: 11 Sep 92 22:53:13 GMT
Distribution: na
Organization: Rutgers Univ., New Brunswick, N.J.

mcirvin@husc8.harvard.edu (Mcirvin) writes:
>Some parts of the letter seemed odd to me.  It seems like between the lines
>what he's proposing is essentially the cessation of most scientific
>research, and the establishment of some means of requiring that proposed
>research explicitly work toward his stated goals for humanity.  If
>this is the "new contract" he advocates (it's hard to tell), it would be
>utterly stifling.  [...]

I agree, it sounds odd, but I doubt he [George Brown] is calling for
the cessation of scientific research as such.  Reading between the 
lines, I see this as a companion to the recent Senate reauthorization
of NSF (and the new emphasis on top-down direction, i.e. no more basic
grants as such (!) at NIH).  Somehow this kind of popped out of the
Senate - hey presto! all of a sudden, everything has to be directly
related to industry.  "Humanity," I imagine, is somewhat of a smoke-
screen.

I suspect that this may be an attempt by the Senate to encourage
governement assistance to critical industries, which the
Administration has been loath to engage in, and it somehow got out
of hand.  It also may be to get good press in bad economic times.
Everyone likes to cite that industrial R & D dropped like a rock
during the 80s, and many of the companies are too debt-laden to 
bring it back up.  Maybe the powers that be think it will be
economical to just, in effect, contract us out to the Westinghouses of
the world.  I hope not.

Probably one of the reasons George Brown thinks scientists have an 
exalted status is because he knows only big shots (I still haven't
forgiven Leon Lederman for writing in Physics Today that, even if
you can't get to be a tenured professor, a graduate physics education
prepares you for lots of things, even being a plumber!  Thanks, Leon.)
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Hole theory (was: Re: Why do protons outnumber antiprotons?)
Date: 5 Sep 92 15:49:12 GMT
Article-I.D.: husc8.mcirvin.715708152

dwr2560@zeus.tamu.edu (RING, DAVID WAYNE) writes:

>Nonsense. The W pulls a neutrino out of the 'neutrino sea' and rotates
>it into an electron. Certainly in the original hole theory the electron
>didn't need to stay in the state exactly opposite the hole did it? 

I hadn't thought of that!  The original hole theory didn't have
the weak isodoublet degree of freedom, of course, but there's nothing
preventing it from possessing one.  The mechanism would behave exactly
like spin does in pair production from a single virtual photon.

There's still the problem of how one describes bosons in this manner,
except that in hole QED the bosonic field (electromagnetism) was quantized
as a field rather than as particles and holes, and I suppose that if
one rebuilt the Standard Model as a hole theory one would do the same
thing with all the gauge fields and the Higgs.

-- 
Matt McIrvin, Cambridge, Massachusetts, USA
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Is Spacetime Absolute?
Date: 8 Sep 92 01:29:43 GMT
Article-I.D.: husc8.mcirvin.715915783

prim!dave@germany.eu.net (Dave Griffiths) writes:

>Perhaps the expansion of the Universe demonstrates that there is no such
>thing as empty space. To take an analogy with the big-bang, if you imagine
>a man holding a football as being the entire universe, then presumably
>there is _no_ space outside them. If the man now decides to kick the
>football away, then whoosh! space is automatically created and exists only
>as the gap between them (ie the galaxies aren't rushing apart because
>space is expanding, but vice-versa).

This isn't a very precise analogy to the situation in the big-bang
model, because there one generally doesn't think of space as having
a boundary; either it's finite like the surface of a finite object is 
finite, or it's infinite.  In the big-bang model the galaxies are
distributed through all of space, and it's correct to say that the're
no space "outside" the whole system of galaxies.  But the idea isn't
that there's something like a finite expanding sheet of rubber with 
galaxies drawn on it; either there's an *infinite* expanding sheet
of rubber with galaxies drawn on it, or it's something like the
surface of a balloon, which has a finite size but no boundaries.

If the guy threw the football in a small universe it wouldn't
oblige the universe to expand; the ball might circumnavigate
the universe and hit the man in the back.  (Though if it were
something like a static Einstein universe, held at constant size
by a cosmological constant, the action of throwing the ball might
well disturb its delicate equilibrium and eventually send it 
into an expanding phase!)

>Now presumably there is a gravitational
>field between the man and the football - how does the field travelling
>from the man to the football "know" it has to stop when it reaches the
>end of space?

In finite cosmological models there usually is no end of space,
just as the surface of a balloon has no edge.

>Another way of phrasing this question: if after the big-bang, particles
>_hadn't_ been rushing away from each other but had been stationary, would
>the universe/space still have expanded due to the gravitational field being
>transmitted?

In big bang models, the universe expands whether or not there is
any matter.  It expands most rapidly in the case where there is
none (though someone mentioned here a while back that that case
can be seen to be Minkowski spacetime under a coordinate 
transformation...  is this true?)

One expanding universe model related to those favored by steady-
state theorists was the de Sitter model, in which the universe
expanded exponentially.  This universe had no matter in it at all,
at least in its pure version.  Yet it was expanding, as one could
see by looking at the divergence of timelike geodesics.
-- 
Matt McIrvin, Cambridge, Massachusetts, USA 
Newsgroups: sci.physics
From: palmer@sfu.ca (Leigh Palmer)
Subject: Re: Finding published papers for an author
Organization: Simon Fraser University
Date: Tue, 15 Sep 1992 21:37:14 GMT

In article <1992Sep15.192806.3521@ramsey.cs.laurentian.ca>
serge@ramsey.cs.laurentian.ca (Serge Turgeon) writes:

>Is there a system somewhere i can access to get a complete list of
>publication for an author?

Start with the Science Citation Index. It is available (probably on paper) in
your university library.

Leigh Palmer
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Hidden variable theories, was: Uncertainty Princi
Date: 10 Sep 92 19:28:32 GMT
Article-I.D.: husc8.mcirvin.716153312

firth@sei.cmu.edu (Robert Firth) writes:

>In article <mcirvin.716138484@husc8> mcirvin@husc8.harvard.edu (Mcirvin) writes:

>>it just means that it's
>>not possible to transmit a message from event A to event B where B
>>is outside A's ****** light cone.  In this sense all of relativistic 
                 ^^^^^^ was the word "future"
>>quantum mechanics (at least in Minkowski spacetime) is causal.

>Please delete the word "future" from the above.  In no sense does any
>of relativistic quantum mechanics support the implied time asymmetry.

Okay.  I dithered slightly about putting it in.  You're right, of
course.  The interpretation of timelike correlations between 
observables as transmission *from* the past *to* the future is a
consequence of an arrow of time not present in microphysics.
Where it comes from is something we argue about constantly here,
but I wouldn't put it anywhere in the vertices or propagators of
the standard model. (see parenthetical note) 

I justify my original decision to put in the word "future" by the
fact that, operationally, that's what it looks like: if you were
to build any system for sending and receiving messages, since you
remember the past but not the future, you would interpret the
messages as an earlier event at the transmitter causing a later
one at the receiver, not the other way around.  But this probably
has more to do with the murky subtleties of where thermodynamic
irreversibility comes from than with anything in microphysics. 
 
(I know that the standard model has time asymmetry, but
it's of a relatively inconsequential variety, since there's still
CPT symmetry, and time-reversed situations are allowed as long as
you also conjugate the charges and do a parity reflection.  This
doesn't seem to be the sort of arrow of time that makes it hard to
unscramble an egg.)

-- 
Matt McIrvin, Cambridge, Massachusetts, USA 
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: Sun, 13 Sep 1992 22:40:04 GMT

In article <1992Sep13.215932.25713@mp.cs.niu.edu> rickert@mp.cs.niu.edu (Neil Rickert) writes:
>If you want to look at it this way, then the officers are those using
>set theory in topology, measure theory, etc.  The troops are solving
>specific applications.

Family values well in place, I see.

>The foundation people are neither officers nor troops

The officers in my scenario weren't foundations people per se, but
rather leading mathematicians of the day taking a strong interest in
foundations simultaneously with their nonfoundational work.  Today's
foundations people contain a mixture of officers and troops, I imagine
I'd got shot at if I tried naming some.  But assuming the distinction
can be made at all reliably, e.g. by a suitable variant of one of those
personality tests, it is an interesting question to ask how the
distribution varies between subjects.  Are there too many chiefs--or
indians--in subject X?
-- 
======================================================| God found the positive
Vaughan Pratt   pratt@cs.Stanford.EDU   415-494-2545  | integers, zero was
======================================================| there when He arrived.
Newsgroups: sci.physics