HDTenEightyP/NetNews huggingface dataset:
From: frisinv@alleg.edu(Vincent Frisina)
Subject: Re: Nevada Casino - 200 miles up
Organization: Allegheny College
Date: Mon, 17 Aug 1992 13:13:09 GMT

In article <64161@cup.portal.com> Eric_S_Klien@cup.portal.com writes:
> I have some questions that people don't seem to be able to answer in 
> sci.space.
>  
> Situation:  I need to place a casino 200 miles over Nevada with a 
> tether below it for elevators.  I have access to 2026 AD technology.  
>  
> Questions:  What amount of power would the casino need to stay over 
> one spot in Nevada?  What would be a good source of this power?  What 
> should the tether be composed of?  What will be the weight capacity 
> of the tether?  
>  
>                                                            Eric Klien
   Could you be more exact as to what 2026 AD technology is?
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Annihilation?
Date: 13 Aug 92 18:39:10 GMT
Distribution: na

sichase@csa2.lbl.gov (SCOTT I CHASE) writes:

>[Of the two spin alignments, only one is the ground state...]
>So our two statements are not inconsistent - just two different 
>ways of describing the same thing.  The confusion seems to have 
>been in your description of a "spin-aligned ground state" which doesn't
>exist.

You said that S-states could only decay into even numbers of 
photons... in the terminology that I usually use, the designations
"S" and "P" refer to the spatial part of the state, so both ortho-
and para-positronium would be S states in their lowest-energy
incarnations, though only the para version would be the ground
state.

Was I wrong to say that the spin-aligned version can decay
into three photons, even if it's spatially in an S wave?
I'm trying to think whether parity messes this up, but
my brain is going fuzzy.  Certainly there are no problems
with angular momentum conservation.

Or were you talking about total angular momentum rather
than just the spatial wave function? 

At any rate, for Ric Peregrino, the short answer is that,
yes, the spin-aligned version is longer-lived because it
has to decay into more than two photons.  This is a less
likely event because more interaction vertices, and therefore
more factors of 1/137, go into the decay rate. 

-- 
Matt McIrvin, professional gradgrind, amateur Usenet drifter 
Newsgroups: sci.physics
From: dooley@helios.physics.utoronto.ca (Kevin Dooley)
Subject: Re: Vector Bosons?
Organization: University of Toronto Physics/Astronomy/CITA
Date: Thu, 13 Aug 1992 15:32:06 GMT

In article <d==y5bh@rpi.edu> caer@iear.arts.rpi.edu (Charlie Figura) writes:
>
>Perhaps some of you brilliant minds out there can explain a thing

I hope I'll do instead....

>to me...  somewhere (dont ask me, I dont know where) I heard of such
>a thing called a vector boson.  Now, I understand what bosons are,
>i.e, particles that obey the Bose-Einstein statistics.  I don't know,
>however, what a *vector* boson is.  

In a nutshell, the 'vector' refers to the angular momentum of the particle.
A vector transforms under Lorentz transformations according to certain rules
which you can find in any book on high energy physics.  In particular, a
vector boson has spin of 1 (in units of hbar).  A scalar has spin 0, a
tensor has spin 2.  The term also implies a certain parity.  If I reflect
a vector in the mirror I get a vector of the same length pointing in the
opposite direction so a vector boson such as a photon or a W or Z has
negative parity.  Tensors and scalars have positive parity.  A particle
with the wrong parity gets 'pseudo' tacked on in front.  So, for example
a pion which has zero spin but negative parity is called a 'pseudoscalar'
while a b meson (not B, but b) which has spin 1 and positive parity is
called a 'pseudovector'.

Kevin
Newsgroups: sci.physics
From: jbaez@euclid.mit.edu (John C. Baez)
Subject: Quark-gluon plasmas
Organization: MIT Department of Mathematics, Cambridge, MA
Distribution: na
Date: Mon, 17 Aug 92 20:03:35 GMT

In article <25518@dog.ee.lbl.gov> sichase@csa2.lbl.gov writes:
>In article <1992Aug14.195651.22652@galois.mit.edu>, jbaez@zermelo.mit.edu (John C. Baez) writes...
>> 

>One signature that has gotten some broad attention is "J/Psi suppression."
>The idea is that in a collision which passes through a QGP phase, 
>charm-anticharm pairs which are formed in individual parton-parton interactions 
>are Debye screened from one another due to the "melted vacuum" of the QGP,
>which is no longer confining.  There will be a larger tendency toward
>producing open charm in such a collision than one in which a QGP is not formed,
>leading to a suppression of dileptons at the J/Psi mass, a fairly 
>straightforward experimental signature.  

I love to hear real physicists talk.  Mainly because I can't quite
understand it.  I can sort of believe that something like Debye
screening would occur between charm-anticharm pairs.  So then you're
saying that this allows them to wander apart and, when they cool down,
form a pair of charmed hadrons, e.g. J/Psi's?  Okay.  Now what are
"dileptons"?... well, they've gotta be pairs of leptons.  But when WHAT
is near the J/Psi mass do you expect suppression of the formation of
dileptons, and why?  The energy of the charm-anticharm pair?  Half that?
Newsgroups: sci.physics
From: jbaez@zermelo.mit.edu (John C. Baez)
Subject: Re: the nature of exclusion
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Fri, 14 Aug 92 21:04:29 GMT

In article <1992Aug14.020848.11073@math.ucla.edu> barry@arnold.math.ucla.edu (Barry Merriman) writes:
>we all know that fermions satisfy the exclusion
>priciple, which rules out their being in the same state. 
>
>But what is the operational nature of this exclusion?
>That is, if I take two fermions and try to put them in the
>same state, what stops me?

How are you going to try?

>Presumably there would be some "resisting force", but on the
>other hand, none of the four forces seem to come into play.
>I've heard it called statistical repulsion, which is a nice way to
>avoid discussing what is going on.
>
>I realize the exclusion is reflected in the symetries of the 
>wave function, but I feel like I could try and force the wave
>function out of this particular type of symmetry, and I wonder what prevents
>me from actually doing it.

I don't think anyone can answer your question until you make a
suggestion for how you might try to "force" the wavefunction out of this
symmetry!  

E.g.: "Why is 2 + 2 = 4.  What stops me if I try to add two and two and
get 5?"  "Well, how are you going to "try" to do that?"

Certainly compressing a gas of fermions is harder than compressing a gas
of bosons because of Pauli exclusion.  You can say "I'll try hard to
squeeze it down so they all get squished into the same state" -- but
even as you squeeze down the position you let your fermions occupy,
there's plenty of room in *phase* space -- they will just get squished
over to regions of high momentum hence high energy -- so it takes a lot
of energy to squish down a fermionic gas.
From: boudouvi@ntua.gr (Andreas Boudouvis)
Newsgroups: sci.physics
Subject: sea waves
Summary: waves colour
Keywords: waves
Date: 18 Aug 92 13:34:30 GMT
Organization: National Technical University of Athens


A summer-time question:
Why the crests of sea waves are white (esop. when the waves 
break at the seashore?)

Andreas Boudouvis
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Simple QED question
Date: 20 Aug 92 01:18:58 GMT
Article-I.D.: husc8.mcirvin.714273538

ric@hpspdla.spd.HP.COM (Ric Peregrino) writes:

>I was reading Feyman's QED and came across the diagram which
>shows one photon splitting into an electron and a positron.
>Then I started thinking (silly me...)

[...that it's kinematically forbidden for one photon to split
    in such a way!]

>This contradicts conservation of energy and momentum. What gives?

What gives is the possibility of that process for real particles.
You're right: a photon that obeys the law of motion can't split
into an electron and positron that likewise obey their law of
motion, in free space.  That's why photons don't spontaneously
decay electromagnetically.

So how should we interpret that vertex?  Well, this is kind of
complicated, because it involves the issue of what a virtual
particle really is.  Feynman probably explains this better than
I can, but when you calculate transition probabilities and other
things using Feynman diagrams, you act as if there are such things
as particles which can disobey the laws of motion.  The 4-momentum's
length doesn't necessarily have to be the mass (or zero, for photons).
The photon simply can't live long and be detected with such a momentum.

So a process that looks like a single vertex doesn't happen, but
one in which two or more vertices are hooked together, to make a
more complicated diagram in which the unconnected legs *do* obey
the laws of motion, can happen-- even though the internal lines
disobey those laws.

There are several ways of thinking about this.  One is that virtual
particles are just a calculational artifact for what is really a
matter of interacting fields; virtual particles aren't really
*traveling* excitations of fields, so they don't have to follow the
same rules.

Another way is to think of this picture as another way of slicing the
usual nonrelativistic treatment.  When one does nonrelativistic 
perturbation-theoretic calculations (actually relativistic ones can
be done in this way too), one treats intermediate states as possessing
energy and momentum as given by the laws of motion for fields and
spatial wave functions, but allows them to violate energy conservation
for short times, in keeping with the time-energy uncertainty principle.
In the covariant treatment, energy and momentum conservation are 
restored, but the laws of motion can be violated somewhat.  The results
that appear are the same; the approaches are logically equivalent.
The approach involving Feynman diagrams is more convenient for most
relativistic problems.
-- 
Matt McIrvin, Cambridge, Massachusetts, USA 
Newsgroups: sci.physics
From: rscott@csws17.ic.sunysb.edu (Robert Scott)
Subject: Re: ORTHODOX SPECIAL RELATIVITY
Organization: State University of New York at Stony Brook
Date: Tue, 18 Aug 1992 17:26:26 GMT

In article <MATT.92Aug17191221@physics2.berkeley.edu>
  matt@physics.berkeley.edu writes:

>Various people have made interesting comments about this, but there is
>one important point that nobody has made yet.
>
>This is that from the standpoint of field theory, even if you have a
>theory which is classically invariant under dilation,
>quantum-mechanical effects will break this invariance!  (Unless, of
>course, the theory is trivial, and includes no interactions at all.)
>In other words, to use technical language, conformal symmetry has an
>anomaly: even if a theory looks conformally invariant, it probably
>isn't.
>
>You can see this by thinking about the renormalization group:
>renormalization necessarily introduces some length scale into the
>problem, even if one is not present in the classical theory.
>
>Sidney Coleman has a nice discussion of this in his book, _Aspects of
>Symmetry_. 

IF I MAY BE PERMITTED TO LOWER THE SOPHISTICATION OF THE DISCUSSION A
FEW NOTCHES:

I DON'T QUITE HAVE THE BACKGROUND TO UNDERSTAND THE DETAILS OF WHAT
YOU'RE SAYING, BUT IT DOES SOUND INTERESTING.  I WONDER IF IT COULD EVEN
BE RELATED TO THIS:

IN MY ORIGINAL DISCUSSION OF THE DILATION-PLUS-POINCARE-INVARIANT ROBOT
GAME, I MENTIONED THAT THE ROBOTS COULD EASILY BE PROGRAMMED TO
SIMULATE RELATIVISTIC ELASTIC COLLISIONS BETWEEN MASSIVE PARTICLES LIVING
IN ONE SPACE DIMENSION AND ONE TIME DIMENSION.  JOHN BAEZ THEN OBSERVED
THAT DILATION-PLUS-POINCARE SYMMETRY IS TYPICALLY ASSOCIATED WITH MASSLESS
PARTICLES.  THIS SEEMED LIKE A VERY FUNNY CONTRAST AT FIRST, THAT MY
ELASTICALLY COLLIDING MASSIVE PARTICLES RESPECT A SYMMETRY THAT IS
TYPICALLY ASSOCIATED WITH MASSLESS PARTICLES.  I TENTATIVELY CONCLUDED THAT
THIS JUST DEMONSTRATES THAT CLASSICAL ELASTIC COLLISIONS ARE A RIDICULOUSLY
OVER-SIMPLIFIED TOY MODEL OF REAL INTERACTIONS BETWEEN MATTER.

SO NOW WHEN I TRY TO PICTURE TO MYSELF WHAT IS IT ABOUT A MASSIVE QUANTUM
PARTICLE THAT PREVENTS IT FROM BEHAVING IN A DILATION-INVARIANT WAY, I KEEP
ON THINKING THAT MASS MUST CORRESPOND TO SOMETHING LIKE "THE EXPECTED
NUMBER OF TIMES PER PROPER SECOND THAT THE QUANTUM PARTICLE UNDERGOES A FIT
IMPEDING ITS FORWARD MOTION", OR SOMETHING.  THAT WAY THE PARTICLE WILL
BE ABLE TO KEEP PROPER TIME, BREAKING THE DILATION SYMMETRY.

RE-READING THE ABOVE I'M NOT SURE I SEE ANY LOGICAL INTERCONNECTIONS
BETWEEN MY THIRD PARAGRAPH, MY FOURTH PARAGRAPH, AND MATT AUSTERN'S
ORIGINAL COMMENT.  IT STILL FEELS LIKE THERE'S A COMMON IDEA IN THERE
SOMEWHERE, THOUGH.


-JAMES DOLAN
From: sichase@csa3.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: How to make big bucks using supersymmetry
Date: 20 Aug 92 19:42:04 GMT
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
Distribution: na
Reply-To: sichase@csa3.lbl.gov
NNTP-Posting-Host: 128.3.254.198
News-Software: VAX/VMS VNEWS 1.3-4   

In article <MATT.92Aug19225852@physics16.berkeley.edu>, matt@physics16.berkeley.edu (Matt Austern) writes...
>It also isn't at all easy to drive a stake through the heart of the
>MSSM; all any experiment can do is to exclude some region in this
>multi-dimensional parameter space, and there will always be some
>allowed region left.

For a while, people were talking about a definitive test by searching for the
lightest MSSM neutral higgs.  The mass was supposed to be constrained to be
less than the Z mass, if I remember correctly.  Unfortunately, someone bothered 
to calculate the radiative corrections, and the whole plan was ruined.  Do 
you know if there is still an upper bound on the mass - or do the 
corrections leave things wide open?  

-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: franl@centerline.com (Fran Litterio)
Subject: Re: BLACKHOLES IN THE CENTRE OF THE EARTH
Organization: CenterLine Software, Inc.
	<5117@tuegate.tue.nl> <mcirvin.714262558@husc8>
Date: Thu, 20 Aug 1992 20:59:43 GMT

mcirvin@husc8.harvard.edu (Mcirvin) writes:

> Getting back to the subject, I'd expect a black hole small enough
> not to cause the Earth's orbit major disruption to go straight
> through the Earth and come out the other side, if it fell 
> straight in from a great distance.

> The hole has to heat the
> Earth sufficiently to get its kinetic energy below the amount
> required for escape, and that kinetic energy is enormous, 
> depending on the mass of the hole.
> 
> If the black hole were traveling at typical solar system speeds to
> begin with, it might be captured in some sort of multi-body
> interaction, like some of the moons of assorted planets.  Then,
> if it fell into the Earth, it wouldn't escape upon emergence,
> but would instead rise to some enormous height and fall back,
> punching repeatedly through the Earth in a series of slowly
> damped oscillations.

Of course, you assume that the hole approaches a pre-existing Earth.
Perhaps the Earth (and planets and moons and maybe even the Sun)
condensed around pre-existing miniature black holes.  Currently, such
condensation is attributed to random fluctuations in the density of
the could of gas and dust that the Solar System formed out of.
--
franl@centerline.com   || Fran Litterio                               
uunet!centerline!franl || CenterLine Software R&D                     
617-498-3255           || 10 Fawcett St, Cambridge, MA, USA 02138-1110
From: ted@physics3 (Emory F. Bunn)
Newsgroups: sci.physics
Subject: Re: Vector Bosons?
Date: 13 Aug 1992 21:12:10 GMT
Organization: /etc/organization
NNTP-Posting-Host: physics3.berkeley.edu

In article <d==y5bh@rpi.edu> caer@iear.arts.rpi.edu (Charlie Figura) writes:
>
>Perhaps some of you brilliant minds out there can explain a thing
>to me...  somewhere (dont ask me, I dont know where) I heard of such
>a thing called a vector boson.  Now, I understand what bosons are,
>i.e, particles that obey the Bose-Einstein statistics.  I don't know,
>however, what a *vector* boson is.  

"Vector" just means spin-1.  So the photon, W and Z are all vector
bosons.

The full story is that spin-0 particles are called "scalar",
and particles of some integer spin n>1  are (I think) called 
"rank-n tensor" particles.  At least that would be the logical
scheme.  In fact, people refer more often to "spin-n" particles,
which is probably better anyway.

The reason for the terminology is that the field associated with
a spin-1 particle obeys the same transformation equations as a
vector when you change coordinate systems.  Spin-0 fields don't
need to be transformed at all under coordinate system changes,
so they're "scalar."  Etc.

-Ted
From: An-Ly Yao <anlyyao@igc.apc.org>
Newsgroups: sci.physics
Date: 17 Aug 92 08:43 PDT
Subject: Re: Hubble constant?
Nf-ID: #R:cdp:1468500004:cdp:1468500006:000:61
Nf-From: cdp.UUCP!anlyyao    Aug 17 08:43:00 1992



Thanks for all the answers!
Goetz Kluge
anlyyao@igc.apc.org
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Blue Sky and Olbers' Paradox
Date: 13 Aug 92 20:09:53 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

Andrew Mullhaupt writes:
>You are in danger of fragmenting physics into a disconnected set of 
>fragmentary explanations valid only in the neighborhood of legitimate
>observations. 

It's not already?

>This kind of physics has very strange versions of things like the second
>law of thermodynamics.

I wouldn't trust any kind of physics in which the second law of
thermodynamics was anything other than faintly mysterious.  It's
a law of thermodynamics, anyway, induced from and valid in
thermodynamics.  If you want to pretend to "derive" it from something
else you wind up making equally [valid/absurd] assumptions which
are no less mysterious - the postulate of equal a priori
probabilities ... the ergodic hypothesis, anyone?  If someone asks
me why you can't make a perpetual motion machine, I don't feel like
responding "I can't prove that you can't, because I can't prove the
ergodic hypothesis."

>Note that the scientific method does not make these choices for you. The
>scientific method is essentially intact even if you decide that 'observation'
>means conducting an a priori computation using Conway's cellular automaton.
>In one sense this is obvious - you can do science on some restricted piece
>of the 'universe', but the upshot is that you cannot use the scientific method
>to guarantee that your choices of observations are in any sense 'complete',
>since the method is perfectly happy with a restricted choice.

I thought it was fairly well conceded by now that scientists do not
proceed by the "scientific method" as it is usually set forth.

Ben Weiner
---
"Which is the greater crime, to rob a bank or to own one?"  - Brecht
Xref: sparky sci.physics:12826 sci.math:10256
From: dmrrsn@math.duke.edu (David R. Morrison)
Newsgroups: sci.physics,sci.math
Subject: Re: Symmetries, groups, and categories
Date: 14 Aug 92 02:25:36 GMT
Followup-To: sci.physics
Organization: Duke University; Durham, N.C.

In article <1992Aug13.182411.11593@galois.mit.edu> jbaez@riesz.mit.edu (John C. Baez) writes:
>I will begin with a thoroughly fictionalized account of the quest in
>physics to find bigger and bigger symmetry groups.  

[lots of stuff deleted]

>(In practice various sneaky things - infrared slavery and Higgses -
>conspire to cloak the conformal invariance of the fields in these
>cases, so the practicla relevance of conformal symmetry is limited.)

OK, John, I'll bite:  what's "infrared slavery"?

[lots more stuff deleted]

>We can think of this as a spacetime where two 1-dimensional circular
>universes collide and form one!  Or we can think of it as a tubular
>Feynman diagram.  Weird, huh?  

Gee, John, I hate to point this out but the tubular Feynman diagram
interpretation leads to string theory!  I'm happy with it, being a 
string theory fan myself, but from you...?

All light-hearted comments aside, I have to agree with Scott Chase:  that
was awesome.  Thanks.

---

Dave Morrison, Dept. of Math., Duke University:  dmrrsn@math.duke.edu
Newsgroups: sci.physics
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Superbashing (was Re: SARFATTI LECTURES ON SUPER PHYSICS #1)
Date: 13 Aug 92 18:56:43 GMT
Reply-To: sichase@csa2.lbl.gov
Distribution: na
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
NNTP-Posting-Host: 128.3.254.197
News-Software: VAX/VMS VNEWS 1.3-4

In article <phfrom.240@nyx.uni-konstanz.de>, phfrom@nyx.uni-konstanz.de (Hartmut Frommert) writes...
> 
>Don't fix me, and don't beat me, but if I remember right, unitarity as well
>as renormalizability have been proven for the SM in the 70's by Weinberg,
>t'Hooft, and others. Problems arise from the nonlinearity of the Higgs
>theory (i.e. field equation) -- no superposition, etc. I'm rather sure that
>self-consistency of the SM is granted. 
> 

I don't mean to beg off on your question - but the discussion has gotten
to the point where I have to go back to do a little brushing up, so 
I can't give you a good answer right now.  Maybe Matt or someone will jump
in here.  In any event, I'm out of town for a couple of days.  I'll try
to respond intelligently by the beginning of next week.

-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: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Blue Sky and Olbers' Paradox
Date: 17 Aug 92 20:48:34 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 <1181@kepler1.rentec.com>, andrew@rentec.com (Andrew Mullhaupt) writes...

>conserved. Let's see how far we can get by deciding that parity is 'kind of'
>conserved. So, physicists may think that physics is a disconnected net of

I don't understand this statement at all.  In atomic physics, parity *is*
kind of conserved.  I.e., it is conserved up to small weak corrections
which allow parity-violating transitions will tiny probability.  The same
thing is true in all electromagnetic systems, which develop small 
parity-violating amplitudes from weak radiative corrections.  That doesn't
invalidate the usefulness of parity conservation as an idea or as an 
organizing principle.  It just means that we have a deeper understanding
of the physics than we used to when we thought that parity was never 
violated.

-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