HDTenEightyP/NetNews huggingface dataset:
From: nicho@VNET.IBM.COM
Newsgroups: sci.physics
Subject: Re: Report on Philosophies of Physicists
Date: 14 Sep 92 09:33:24 GMT
Reply-To: nicho@vnet.ibm.com

In <Sep.11.17.58.06.1992.2705@ruhets.rutgers.edu> Benjamin Weiner writes:
> -- description of 'western' bad guys deleted --
  I'm not going to give you a history lesson. Suffice it to say that
viewing your append in the best possible light says that
China is still commiting acts that we gave up regarding as 'acceptable'
decades ago. Mistu has managed to respond thoughtfully to this point,
when do you intend to start ?
>
>Greg Nicholls, I know you identified this as a cheap shot, but why
>did you even bother making it?  It's plain old xenophobia, or worse
>yet, Yellow Peril-ism.
  It's reality kiddo.
>It seems like all your posts are cheap shots
>or rants about you'll never let supposed enviro-fascists take away
>your car.  Get a new topic.
   Oh dear, have I mentioned my cars here sometime ??? that _was_
naughty of me, wasn't it. I bothered making the point, because
the proponents of 'Eastern' philosphy had, up till that point,
tacitly assumed a moral superiority that I considered unwarranted.
Let he who is without sin ...
 If you've got anything else to say, do it by email please.
Apologies to the rest of you.
 -----------------------------------------------------------------
               ** Of course I don't speak for IBM **
Greg Nicholls ... nicho@vnet.ibm.com or nicho@cix.compulink.co.uk
                  voice/fax: 44-794-516038
Newsgroups: sci.physics
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Subject: Re: Units (was Re: E=MC^2)
Organization: Intel Corp., Chandler, Arizona
Date: Sat, 5 Sep 1992 18:58:33 GMT

In article <65184@cup.portal.com> Eric_S_Klien@cup.portal.com writes:
>= 2.5e7 kW-hr, i.e. 25 million kilowatt-hours. Happy now?" 
>Can anyone convert this into energy of sticks of TNT?

No, I just like the fact that at 4cents/kWh it works
out to an even $1Million.

				--Blair
				  "A gram of what?"
Xref: sparky sci.physics:14343 sci.math:11179
From: baez@ucrmath.ucr.edu (john baez)
Newsgroups: sci.physics,sci.math
Subject: Re: Report on Philosophies of Physicists
Date: 4 Sep 92 22:41:56 GMT
Followup-To: sci.physics
Organization: University of California, Riverside

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.
From: christos@kuhub.cc.ukans.edu
Newsgroups: sci.physics
Subject: WHAT IS LIFE? A BOOK BY SCHRODINGER!!!
Date: 5 Sep 92 15:49:13 CDT
Organization: University of Kansas Academic Computing Services

Hello there,

	the scientific American magazine has published a special issue about
the 5 most important developments in scince and technology of the 20th century.
I believe that this issue was published about a year ago. One of the articles
was by Andrew Schrodinger. 

	In that article there was a brief summary about the author(Schrodinger)
and it mentioned that Schrodinger has written a book with a title: "What is
Life?". 

	I am very interested to find the publishing company of this book so
that I can order it. Does anybody have any information about this book or any
information how to get it? Maybe getting the address of Scientific American and
asking them or a telephone number?

	I would appreciate any useful response. Feel free to send e-mail to the
following accounts:
Internet:
Cneophytou@tesla.ece.ukans.edu
Bitnet:
christos@ukanvax.bitnet

Thanks,
Chris.
Newsgroups: sci.physics
From: forbush@vxdesy.desy.de
Subject: Re: Grad School
Organization: (DESY, Hamburg, Germany)
Date: Mon, 14 Sep 1992 10:36:14 GMT

In article <1992Sep13.190539.18622@hubcap.clemson.edu>, taylors@hubcap.clemson.edu (C. Taylor Sutherland III) writes:
> -- 
> 	I've heard a good .sig can let you meet people....
> 	Anybody got any good ideas for one?
> The Fly Boy  <| E-MAIL:  taylors@hubcap.clemson.edu |>
> +--<| My life is a math question with one equation and 42 unknowns. |>--+

Only 42 unknowns?? Why limit yourself?


-- 
Mike Forbush

forbush@panofsky.desy.de


 Mars is essentially in the same orbit... somewhat the same distance from the
 Sun, which is very important. We have seen pictures where there are canals,
 we believe, and water. If there is water, that means there is oxygen. If
 oxygen, that means we can breathe.
       -- Vice President Dan Quayle
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: gravity/height
Keywords: mount everest
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Wed, 16 Sep 92 01:19:10 GMT

In article <1992Sep15.201119.27068@voder.nsc.com> pad@galaxy.nsc.com (Paul Denny x8349) writes:

>The problem was something along the lines of how much
>less do you weigh at the top of everest than at sea level?
>The answer was arrived at by calculating the lower gravity
>due to the inverse square law at further distances from
>the centre of the earth as a recent poster has done. My
>argument is that on top of everest you have the additional
>mass of the mountain attracting you (or bending spacetime
>I suppose) and therefore you will weigh *more* on top of
>everest. 

You will weigh less.  The point is, you are pulled down not just by the
ground right underneath you but by that whole ball of earth we call
Earth.  First imagine that we remove Mt. Everest and you are
simply sitting in an airplane up where the mountain top WOULD be.
I hope that in THIS case you agree that your weight would be less
according to the inverse square law.  Say your weight at sea level was
W; now your weight will be about

W r^2/(r+h)^2

where r is the radius of the Earth and h is the height of Mt. Everest.

Okay - now put Mt. Everest back and land
your plane on it!  You weigh more now, true, because of the
gravitational pull of the mountain itself.  Call this pull P.  Now
your weight is about

W r^2/(r+h)^2 + P 

If 2h/r is a lot bigger than P, which it is, this is LESS than W.  

Okay.  The above simply assumed that Mt. Everest is a big hunk of rock 
that simply sits on top of the earth.  This isn't so; there's a
principle in geology called isostasy (?) which says that mountains, and
the rock supporting the mountains, are less dense than the rest of the
rock.  In other words, mountains essentially FLOAT on the mantle, like
an iceberg floats in the water.  This effect means you are even lighter
on Mt. Everest than the above idealized calculation would suggest.

Plus, I know there's an old scam that involves "making gold grow" by 
taking it up into the Himalayas, weighing it, carrying it back down
whil chanting religious chants, and then weighing it again.  Least
that's what I've heard.



Newsgroups: sci.physics
From: jarleb@athena.uio.no (Jarle Brinchmann)
Subject: Re: Question of Theory of Everything (or Grand Unified theory)
Reply-To: jarleb@athena.uio.no (Jarle Brinchmann)
Organization: University of Oslo, Norway
Date: Wed, 9 Sep 1992 13:54:37 GMT

In article <88251@netnews.upenn.edu>, weemba@sagi.wistar.upenn.edu
(Matthew P Wiener) writes:
> In article <1992Sep8.023027.15883@nuscc.nus.sg>, matmcinn@nuscc
(Mcinnes B T (Dr)) writes:
> >Now: is it not truly astounding that the complexity of the universe
> >is so precisely calibrated to the intelligence of homo sapiens?
> 
> I think Einstein had a famous quotation on just this point. 
Something
> about the most incomprehensible thing about the universe being that
it
> is comprehensible.
> -- 

And then there is Douglas Adams version :

Some say that the universe is made so that when we are about to
understand it
it changes into something even more incomprehensible ---

And then there are those who say that this has already happened.


					Jarle.
From: hagerman@ece.cmu.edu (John Hagerman)
Newsgroups: sci.physics
Subject: Measuring the Universe
Date: 15 Sep 92 01:56:33 GMT
Distribution: sci
Organization: Carnegie Mellon University

When someone says "The universe if 20 billion years old," how is that
measure affected by relativity?  Is it unambiguous?

On a related topic, I'll ask a FAQ not in the FAQ.  What would be the
radius of a black hole containing the mass of the universe?  Current
cosmological thought surely considers times when the universe was
smaller than this; what are the implications?  Specifically, how can
we say anything about the physics of the universe at such times, if we
are reluctant to say anything about physics inside a black hole?

- John
--
hagerman@ece.cmu.edu
From: aw3@ukc.ac.uk (A.Wilson)
Newsgroups: sci.physics
Subject: Re: How do we know individual photons exist?
Date: 15 Sep 92 12:01:15 GMT
Reply-To: aw3@ukc.ac.uk (Alan Wilson)
Organization: Chemical Laboratory, University of Kent at Canterbury, CT2 7NH, UK

In article <1992Sep15.180630.913@prim> prim!dave@germany.eu.net (Dave Griffiths) writes:
>
>Having just re-read the description of the 2 slit experiment and the
>implications of wave/particle duality, I was wondering how we know
>that individual photons exist? I'm under the impression that the answer
>is that they cause excitation of an electron from one state to another.
>
>But couldn't the inteference seen in the 2 slit experiment be explained
>if instead of just one photon, the source emitted, say, 1000 sub-photons?
>The source could be continually spraying out a stream of these sub-photons.
>As they travel through space, their phase changes. The electrons in the
>target screen act like containers for these photons. Sub-photons of
>different phase cancel each other out (gulp). When an electron has collected
>1000 sub-photons, it's state changes.
>
>Does the 2 slit experiment definitely correlate an emitted photon at
>the source with a detected photon at the screen, or is it just based
>on aggregates? (I have in mind that the state of an electron at the
>source drops once it has emitted 1000 sub-photons, but such a drop
>would not correlate with an excitation at the screen).
>
>The thing I don't understand is when people talk about placing a
>detector at one of the slits to determine which of the slits the photon
>went through. How is this done? Roger Penrose says that the passage of
>the photon is not disturbed, but it's presence is somehow inferred from
>detectors placed elsewhere.
>
>Dave Griffiths

On a similar note, I recall reading an article a long time ago, based on
the same sort of subject, entitled "Take a photon.." (it may have been
Otto Frisch, maybe not). The point was that it was in fact, difficult
... to say the least! Perhaps someone with a clearer memory can confirm
the existence of the article and its relevance.

Al

--
Alan Wilson        (insert YOUR favourite witty remark..........)

"You would NOT believe what has been going on behind there" 
=================================================================
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Newsgroups: sci.physics
Subject: Re: Measuring the Universe
Date: 16 Sep 1992 02:53:00 GMT
Distribution: sci
Organization: Texas A&M University, Academic Computing Services
News-Software: VAX/VMS VNEWS 1.41

hagerman@ece.cmu.edu (John Hagerman) writes:
>>On a related topic, I'll ask a FAQ not in the FAQ.  What would be the
>>radius of a black hole containing the mass of the universe?  Current
>>cosmological thought surely considers times when the universe was
>>smaller than this; what are the implications?  Specifically, how can
>>we say anything about the physics of the universe at such times, if we
>>are reluctant to say anything about physics inside a black hole?

We are only reluctant to say anything about physics near the singularities,
in both cases.

Dave Ring
dwr2560@zeus.tamu.edu
Newsgroups: sci.physics
From: brahm@cco.caltech.edu (David E. Brahm)
Subject: Re: Why do protons outnumber antiprotons?
Summary: B-violation in the Standard Model is common at high T
Organization: California Institute of Technology, Pasadena
Date: Sun, 13 Sep 1992 07:10:25 GMT

matt@physics.berkeley.edu wrote:

> baryon number violation in the Standard Model proceeds through topological
> effects, and is suppressed by a factor of something like exp(-1/alpha).
> This is tiny enough so that I tend to think of this effect as a
> theoretical curiosity that probably has no experimental implications at
> all.  (Unless, of course, something odd happens at very, very high
> temperatures; I've never heard of any suggestions that might be the case,
> though.)

Matt must have missed my earlier post, so I'll repeat:
The Standard Model vacua are separated by potential barriers, which you can
either tunnel through (highly suppressed, as he says) or be thermally
excited over.  At temperatures above the barrier height (the "sphaleron
mass", about 10 TeV -- that's not so high) it's very easy to violate baryon
number.  It's also possible that at comparable energies (i.e. SSC energy)
B-violation will be seen.

--
Staccato signals of constant information,  |  -- David Brahm
A loose affiliation of millionaires and    |  (brahm@cco.caltech.edu)
  billionaires and Baby ...                |---------------------------
These are the days of miracle and wonder,  | Disclaimer:  I only speak
And don't cry, Baby, don't cry, don't cry. |   for the sensible folks.

Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Boson and Fermion variables
Keywords: infinite/finite
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Thu, 10 Sep 92 01:06:17 GMT

In article <1992Sep9.191600.29388@uwm.edu> litow@csd4.csd.uwm.edu (bruce e litow) writes:
>I seem to recall that Dirac, somewhere, indicated that it is possible
>to proceed from the assumption that there are infinitely many fermion
>variables (say associated with electrons) and construct boson variables.
>The infinity was crucial although somewhat unphysical. Can anyone
>give a reference to this or clarify what it is that I think I 
>remember?
>
>
>Bruce Litow
>Computing Services Division
>P.O. Box 413
>Univ. Wisconsin-Milwaukee, Milwaukee, WI, 53201
>litow@convex.csd.uwm.edu

I don't know of any argument by Dirac that constructs bosonic
variables in a situation where there are infinitely many fermionic
variables.  But there is a trick which could be described in this way,
which was used early on by Thirring to show that what is now
Thirring model, a 2-dimensional field theory of interacting fermions,
is equivalent to the sine-Gordon equation, a theory of interacting bosons.  
I don't know where it first appeared - perhaps in Schwinger's work on
what is now called the Schwinger model, which is just 2-dimensional
quantum electrodynamics with massless fermions.   Anyway, this trick
is now called bosonization and huge amounts have been written on it.  
It only works in 2 dimensions, but that's fine in string theory.
In its original context, this trick proceeds by taking the current j_mu(x) 
associated to the fermionic field and writing it as partial_mu phi(x).  
If one works out the commutation relations for  phi  one sees that it 
is a boson field.  Working this out is rather tricky
since it depends crucially on Schwinger terms that arise in the
commutators of j_mu(x), which is a rather singular thing to compute,
but can be computed rigorously (in 2 dimensions!).  These Schwinger terms 
arise when you try to quantize a symmetry of a fermionic system; 
a certain thing goes wrong sometimes when there are infinitely many 
degrees of freedom, and things that naively should commute don't.  
The same mathematical effect is lurking behind "anomalies".

For references to this, I'd try 

S. Coleman, Quantum sine-Gordon equation as as a massive Thirring model,
Phys. Rev. D11, 2088 (1975).

S. Ruijsenaars, Integrable quantum field theories and Bogoliubov
transformations, Ann. Phys. 132, p. 328 (1981).

Carey, Hurst and O'Brien, Fermion currents in 1+1 dimensions, J. Math.
Phys. 24, p. 2212 (1983).

As usual, the mathematical essence of this beautiful trick is obscured
by the various contexts in which one finds it in physics. 
Unfortunately, I don't know a reference that makes it all as simple as
it should be.  For heavy-duty mathematical physicists I recommend the relevant
section of

H. Araki, Schwinger terms and cyclic cohomology, in Quantum Theories
and Geometry, eds. Cahen and Flato, p. 1, Kluwer Acad. Pub., 1988.

Xref: sparky sci.physics:14710 sci.math:11501 sci.logic:1391
From: gudeman@cs.arizona.edu (David Gudeman)
Newsgroups: sci.physics,sci.math,sci.logic
Subject: Re: Computability of the universe
Date: 15 Sep 92 20:21:57 GMT
Followup-To: sci.physics
Organization: U of Arizona CS Dept, Tucson

In article  <1992Sep15.090238.186@nntp.nta.no> Klaus Gaarder FNI writes:

]Classical Physics: ------------------ 	The so-called "three body
]problem", computing the trajectory of three (yes only 3) bodies under
]mutual gravitational (Newton-style) interaction, is not computable.

I thought the multi-body problem is intractable, not uncomputable.  In
any case, all problems of predicting behavior in nature are trivially
computable.  First a definition:

(1) a problem is "computable" iff there exists a computing device that
given an input representing the problem will terminate in finite time
with an output representing the solution to the problem.

To solve any problem in nature: the computing device is the universe,
the input is the initial conditions specified by the problem, the
output is the final conditions.  There are some restrictions on this
of course: first, not all problems that are formally computable are
practicaly computable (not a surprise).  Second, artifical problems
like the 3-body problem have to be reformulated with conditions such
as "given that all other forces acting on the bodies are so small as
not to effect the outcome within the accuracy of measurment".  Third,
the results refer to _measured_ outcomes not theoretical outcomes, but
"problems of predicting behavior in nature" inherently refer to
observation (measurement).  Questions about what Newtonian mechanics
predicts are not strictly problems of determining behavior in nature.
-- 
					David Gudeman
gudeman@cs.arizona.edu
Newsgroups: sci.physics
From: daryl@oracorp.com (Daryl McCullough)
Subject: Re: Hidden variable theories, was: Uncertainty Princi
Organization: ORA Corporation
Date: Thu, 10 Sep 1992 13:38:25 GMT

In article <1992Sep8.144555.455@cine88.cineca.it>,
campo@sunthpi3.difi.unipi.it (Massimo Campostrini) writes:

>Quantum electrodynamics and other relativistic quantum field
>theories are local, according to any reasonable definition of
>locality.

I think you are missing a crucial point in the discussion of the
locality of quantum mechanics or quantum field theory. There are two
aspects of quantum mechanics (and the same holds for quantum field
theory): the evolution of the wave function or field, and the
probabilistic interpretation of the amplitudes calculated from the
wave functions or fields. The first aspect is completely local, but
the controversy is whether the probabilistic interpretation can be
made local. In particular, the "collapse of the wave function" at
first glance seems completely nonlocal. Of course, there are
interpretations of quantum mechanics (such as the Many-worlds
interpretation of Everett) but they are not universally accepted.

Daryl McCullough
ORA Corp.
Ithaca, NY
From: paul@mtnmath.UUCP (Paul Budnik)
Newsgroups: sci.physics
Subject: Re: Computability of the universe
Date: 12 Sep 92 16:48:47 GMT
Organization: Mountain Math Software, P. O. Box 2124, Saratoga. CA 95070

In article <1992Sep11.222036.7483@galois.mit.edu>, jbaez@riesz.mit.edu (John C. Baez) writes:

> ...  Note that the recursivity of the time evolution of the
> wavefunction does NOT contradict the fact that quantum mechanical
> observations can be random, hence not computable. ...

They can be random, but no one knows if they are. That this
would make them not computable is all the more reason to doubt
that they are random.

Paul Budnik
From: brahm@cco.caltech.edu (David E. Brahm)
Newsgroups: sci.physics
Subject: Re: neutrinos & anti-neutrinos
Summary: No photons
Keywords: neutrino, antineutrino,anti-neutrino
Date: 13 Sep 92 07:57:09 GMT
Organization: California Institute of Technology, Pasadena

maxc0452@ucselx.sdsu.edu (Legene) writes...
> Could someone please tell me what the annihilation products
> of neutrinos and anti-neutrinos are?  I'd appreciate it ever-so-much.

sichase@csa2.lbl.gov (the illustrious Scott Chase) writes:
> It depends entirely on the energy of the particles (in the
> center-of-momentum frame) when they collide.  At low energy, it's only
> photons... At higher energy, there are many possibilities.
and before I can jump on him, Scott adds:
> At low energies, add other neutrino-antineutrino pairs of all flavors, 
> assuming that all neutrinos are massless.

Since neutrinos are neutral, [nu + anti-nu -> photons] is a higher-loop
process, and is suppressed.  Thus to a fair approximation, at low energy
(i.e. less than twice the electron mass) the final products are almost
entirely [nu + anti-nu].  Now an s-channel virtual Z gives final neutrinos
in each of the 3 generations, while a t-channel Z preserves the flavor of
the original pair; so I calculate a branching ratio of 2/3 to [nu +
anti-nu] of the same flavor (this is "elastic scattering" rather than
"annihilation"), and 1/6 to [nu + anti-nu] of each of the 2 other flavors.

At higher energies, as Scott says, many other particle-antiparticle pairs
are also made, but photons are still suppressed.

--
Staccato signals of constant information,  |  -- David Brahm
A loose affiliation of millionaires and    |  (brahm@cco.caltech.edu)
  billionaires and Baby ...                |---------------------------
These are the days of miracle and wonder,  | Disclaimer:  I wrote this
And don't cry, Baby, don't cry, don't cry. |   late on a Saturday night.
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Color of electric charges (silly question)
Date: 13 Sep 92 06:12:21 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 <allenk.716328529@harry>, allenk@harry.ugcs.caltech.edu (Allen Knutson) writes...
>Whenever I see pictures of electrons and protons, electrons are green and
>protons are red. (Please don't anyone confuse this with colors of quarks!)
>I remember it being that way in Mr. Tomkins, I think: does the history go
>back further than that? Has anyone seen the convention reversed?

I'm ashamed to say that I have not read Mr. Tomkins.  But I have seen a 
variety of different "color schemes" used in different places.  Personally,
when I think of these things, electrons are yellow, protons are red, and 
neutrons are black.  Neutrinos are definitely black as wells, but pi-zeros
are white.  Photons are transparent.  Gluons, of course, have two colors each.
Kind of like candy canes.  I don't this I have unchanging color assignments 
for the other particles.  What does it all mean?  Probably that I spend too
much time in the office.

-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
Xref: sparky sci.physics:14657 sci.math:11445