HDTenEightyP/NetNews huggingface dataset:
From: tjn32113@uxa.cso.uiuc.edu (Tom Nugent       )
Newsgroups: sci.physics
Subject: Re: Nevada Casino - 200 miles up
Date: 19 Aug 92 20:09:56 GMT
Article-I.D.: news.Bt8yoL.E18
Organization: University of Illinois at Urbana

Eric_S_Klien@cup.portal.com writes:

>"I'd recommend trying to figure out the thrust you'd need.  I think it
>could be a fun problem."
> 
>I'm unable to do this.  Can anyone help?  I'd be interested in the 
>thrust requirements for different attitudes, perhaps 200 miles, 2000 
>miles, 20000 miles, and 23,000 miles.  
> 

You want some large object simply hovering at those attitudes?  Well, to first
order, that's just the weight of the thing.  You want a 100 ton 'building' to
hover at 2000 miles?  Figure out its weight (Gm1m2/r^2).  NOw there are 
second order corrections (dealing with wind and shifts in the weight     
distribution inside), but this is good enough for now.


"The future is a race between education and catastrophe."
		- H.G. Wells 
-- 
Tom Nugent	voice:(217)328-0994	e-mail:tjn32113@uxa.cso.uiuc.edu 
"To be average scares the hell out of me." -- Anonymous
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Vector Bosons?
Date: 13 Aug 92 19:03:02 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 <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.  I've looked in a few basic

Well, since none of the brilliant minds have answered, I'll take a crack
at at.

"Vector" refers to spin.  "Scalar" means spin-0.  "Vector" means spin-1.
"Tensor" means spin-2.  Bosons have integral spin, and so, can come in any
of these (or more) flavors.  You probably already know that vectors in R^3
transform according to a 3 = 2*L+1 dimensional irriducible representation
of S0(3).  But you probably never heard it put that way before.  It just
means that vectors have three components which vary among themselves as
you rotate the vector through an arbitrary angle in space.  In this case,
L = 1, i.e., vectors have "spin-1."  Tensors have more components which 
change as you rotate them (or the coordinate system) and so they 
correspond to higher angular momentum.

In quantum mechanics, you replace S0(3) by its covering group SU(2), 
which then admits half-integral representations as well.  (How am I 
doing, John?!) 

So, getting back to physics, "vector bosons" are spin-1 bosons.  What about
the "intermediate" part?  The EM, Weak, and Strong interactions are all
mediated by particles which transmit the force from one charged particle to 
another.  For example, two electrically charged particles exchange a photon
as their means of interaction electromagnetically.  Two quarks (which have
color charge) exchange one of eight different gluons.  The exchange particles
are all vector bosons, which "mediate" the interaction between the charged
particles.  They are "intermediate vector bosons."  

Side bar:  The interation of quarks is complicated.  They are electrically
and weakly charged as well as having color charge and mass.  So they 
interact by exchanging photons, W's, Z's, gluons, and gravitons (if they
exist).  Gravitons are supposed to have spin-2, and so would rightly be
called "intermediate tensor bosons."

-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: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: How to make big bucks using supersymmetry
Organization: University of Virginia
Distribution: na
Date: Thu, 20 Aug 1992 04:39:47 GMT

In article <1992Aug20.030038.22420@utagraph.uta.edu> sawyer@utahep.uta.edu (Lee Sawyer) writes:
>In article <25611@dog.ee.lbl.gov>, sichase@csa2.lbl.gov writes...
>>In article <1992Aug14.164822.10838@utagraph.uta.edu>, sawyer@utahep.uta.edu (Lee Sawyer) writes...
>>>[about a wager I made] 
>> 
>>Are you kidding?  I'm optimistic, but this is hard to imagine.  I doubt you
>>could get anyone from CDF or D0 to take such a speculation seriously.
>
>Well I am on D0...it's a beauty bet  if we see nothing, everybody sort of
>shrugs their shoulders and moves on. But if we do find something, I look like
>Moses...

    Interesting attitude.  With this philosophy, Jeanne Dixon looks like Moses.

    Have a good day.

                              dale bass
-- 
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926
From: barry@arnold.math.ucla.edu (Barry Merriman)
Newsgroups: sci.physics
Subject: Re: the nature of exclusion
Date: 18 Aug 92 21:46:28 GMT
Organization: UCLA, Mathematics Department

In article <1992Aug14.210429.23650@galois.mit.edu> jbaez@zermelo.mit.edu (John  
C. Baez) writes:
> 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

right, but then that implies as I compress in space I expand in
momentum, which would seem to imply ther temperature goes up. What
if I simultaneously cool the gas as I spatially compress it, say
by keeping in in contact with a low T heat reservoir?

It would seem that this way I can compress spatially (by pushing with
my hands) and compress in the velocity coordinate (by cooling), so 
that I am achieving a compression on phase space. Now, how does
the "statistical repulsion" kick in to resist this?


--
Barry Merriman
UCLA Dept. of Math
UCLA Inst. for Fusion and Plasma Research
barry@math.ucla.edu (Internet; NeXTMail is welcome)
Newsgroups: sci.physics
From: jbaez@nevanlinna.mit.edu (John C. Baez)
Subject: Re: unitarity red herring
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Wed, 12 Aug 92 23:34:14 GMT

In article <92224.152205MRG3@psuvm.psu.edu> MRG3@psuvm.psu.edu writes:
>  John Baez writes:

>The transition in question is
>(|v1>|v2> +|h1>|h2>)/sqrt2 -> (|v1>e^(i phi) +
>|h1>)|v2>/sqrt2
>It is elementary to show that this is norm preserving in that
>the initial state has the same norm as the final state (and
>is equal to one) so that probability is conserved.
>
>-----
>Okay, maybe this is a case of a typo but yet again I have to note that
>this transformation is NOT unitary, since the h2 that appears on the
>left side is simply MISSING from the right side.  A transformation that
>is not 1-1 cannot be unitary.

>To which I respond
>
>But WAIT (sorry for shouting :>), there is one vector in, and one vector out.
>Both have the same norm.  Without additional assumptions, nothing can be said
>about the transformation.  That assumption is of course that the
>transformation acts ONLY on system 2, which I believe we agree is
>desireable on physical grounds.  WITHOUT that assertion, we could
>construct a unitary transformation on the _4_-dimensional hilbert space
>which which reproduces the indicated transition.  It would be nonlocal
>as hell in the proposed circumstances, and ugly as sin in the basis of
>choice (two photon states), but in and of itself, the transition is not
>an indication that unitarity or linearity has been tossed out.  

Thanks to you and Arun Gupta for pointing out that I had utterly misread
your previous post.  It's embarassing but sometimes I skim things and
get screwed up.  Just to prove that I now understand what's going on,
let me restate the point here.  We've got a 4-dimensional Hilbert space
that's the tensor product of two 2-dimensional spin spaces, one over
here with basis v1, h1, and one over there with basis v2, h2.  Thus the
whole system has an orthonormal basis |v1>|v2>, |v1>|h2>, |h1>|v2>, 
|h1>|h2>.  There's no problem getting a unitary operator that maps

(|v1>|v2> + |h1>|h2>)/sqrt 2

to 

(|v1> e^{i phi} + |h1>)|h2>/sqrt 2.

The problem is that there is no such unitary operator that is the tensor
product of two unitary operators, one on each 2-dimensional Hilbert
space.  This is the case because the second vector above is a tensor
product of two vectors, while the first one above cannot be written as a
tensor product of two vectors.  Given a system consisting of 2 parts
that are spacelike separated, the time evolution operator factors as a
tensor product of 2 unitary operators.

>Sorry for the excessive use of CAPS but I've been discussing this with
>Sarfatti directly and feel a little frustrated.
>-mike gallis

Sorry to further frustrate you with my silly post.
Newsgroups: sci.physics
From: ted@physics2 (Emory F. Bunn)
Newsgroups: sci.physics
Subject: Re: Hubble constant?
Date: 14 Aug 92 23:08:14 GMT
Organization: /etc/organization
NNTP-Posting-Host: physics2.berkeley.edu

In article <1992Aug14.211056.23716@galois.mit.edu> jbaez@zermelo.mit.edu (John C. Baez) writes:
>
>Okay, my curiosity is piqued: what's a Pop III star remnant?  After a
>star pops 3 times all that's left is remnants?  :-)
>

This is an example of the maximally obscure terminology so adored
by astronomers.  It is thought that stars can be roughly divided
into "generations," with a star in a given generation having
formed, Phoenix-like, out of the remnants of explosions of 
massive stars from the previous generation.  The most recent
generation of stars is called Population I, while its
predecessor is Population II.  There may or may not have
been a generation before that, but if there was, we would call
it Population III.  Most Population III stars would be too old
by now to still be shining, so they'd be "Pop III star remnants."

As for why the numbering system goes backwards, don't ask.  
It was probably brought to you by the same people who decided
that the classification of stars into spectral types
should follow a simple, intuitive naming scheme, like
O,B,A,F,G,K,M.

(And if you think that's bad, try learning the _completely_ 
haphazard and indecipherable magnitude system for describing 
the luminosity of stars!)

-Ted
From: GRH6@psuvm.psu.edu (Girish Harshe)
Newsgroups: psu.market.forsale,sci.physics
Subject: Physics Books for Sale
Date: 14 Aug 92 03:04:13 GMT
Organization: Penn State University

I have following two Physics books for sale.

1) Quantum Mechanics Vol. I, by Cohen-Tannoudji, Diu and Laloe
             price: $ 45


2) Theoretical Mechanics of Particles and Continua, by Fetter and Walecka
             price: $ 40

They were bought new, but were never used and are in mint conditions.
If interested please e-mail to GRH6@psuvm.psu.edu or call 814-238-9604
Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: Cosmology with point masses
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Thu, 13 Aug 1992 23:40:00 GMT

jbaez@riesz.mit.edu (John C. Baez) writes...
>                             I advise folks to look in Misner Thorne and
>Wheeler's Gravitation, which discuss a universe that is completely empty
>and roughly spherical except for 12 black holes arranged at the faces of
>a regular dodecahedron.  The book even has a cute picture of such a
>space.  I believe Wheeler wrote a paper on this and showed that the
>universe's expansion WOULD slow down due to the presence of the "point
>masses" (really, singularities).  It would be an extreme bummer otherwise.

So that others don't have as much trouble finding it as I did:
it's on p.739

Dave Ring
dwr2560@zeus.tamu.edu


From: ric@hpspdla.spd.HP.COM (Ric Peregrino)
Date: Thu, 20 Aug 1992 17:19:45 GMT
Subject: Re: I can travel faster than light (A riddle)
Organization: HP Stanford Park - Palo Alto, CA
Newsgroups: sci.physics


>Okay, if it's NOT a joke, the THING in the "riddle" is the GROUP VELOCITY
>of a wave packet, which can (apparently) travel faster than c.  But it
>can't carry information.

You mean of course, the PHASE VELOCITY. It can exceed c, for example in
a waveguide. Group velocity is the velocity of the information transfer.
I don't think you can have a wave mode with group velocity exceeding c.
And I mean wave mode as in not an evanescent mode.

--------------------------------------------------------------------------
Ric Peregrino     c/o Hewlett Packard Co.        I represent only myself
ric@spd.hp.com    1501 Page Mill Rd. Bldg. 5M    Buy low, sell high
415-857-7526      Palo Alto, CA 94304            Do DC photons exits?
--------------------------------------------------------------------------
From: weemba@sagi.wistar.upenn.edu (Matthew P Wiener)
Newsgroups: sci.physics
Subject: Re: Weak interactions, biology and the SSC
Date: 13 Aug 92 14:22:46 GMT
Reply-To: weemba@sagi.wistar.upenn.edu (Matthew P Wiener)
Organization: The Wistar Institute of Anatomy and Biology
In-reply-to: magnus@thep.lu.se (Magnus Olsson)

In article <1992Aug13.121304.5717@pollux.lu.se>, magnus@thep (Magnus Olsson) writes:
>However, whether this has any relevance to chemistry and biology is
>doubtful in the extreme -

I'd say it's doubtful in the extreme in the usual sense: no evidence
exists for it, and there is no compelling need for it, and so on.

>			 - the influence of weak interactions on atomic
>physics and possibly chemistry would of course be a low-energy
>phenomenon, and as far as we know, the low-energy behaviour of the
>weak interaction is well understood from earlier experiments.

Your "as far as we know" is precisely my point!  We don't know enough to
get cocksure.

For example, low-energy behavior over eons and eons (as in the origin
of biochirality) may be sensitive to high-energy behavior.  Nor would I
agree that the low-energy behavior is so well understood in the short
term that the only job left now is to move on to higher energies or
merely add precision to the low-energy measurements.  We certainly
know it well enough to have achieved a decent plateau in knowledge,
yet just like chemistry and solid-state physics and so on are still
capable of yielding surprises in the ultra-low-energy realm, I expect
surprises to show up in the known low-energy realm anyway.  And we
can only calculate so far.

I would consider it a tragedy if the SSC killed off further exploration
of the low-energy realm.  I hope for the opposite, with detailed knowledge
of the high-energy realm leading to subtle low-energy predictions.  If I
remember correctly, the expensive early 70s confirmation of the weak
neutral current led to some inexpensive further confirmations, eg, weak
optical activity in an electrically neutral system and others.

As one example of unforseeable complexity, Abdus Salam's J of Mol Evol
article speculated regarding some kind of medium low boson condensate
phase that would enhance the weak current.  I don't recall seeing any
references to the physics literature, so perhaps he's developing something,
or perhaps it's just yet another far out idea.  But it is not something
that we can rule out based on what we know.

Just for the record, my favored scenario for the origin of biochirality
involves the sunlight polarization morning to evening flip combined with
the daily temperature rise favored the dissolution of R-amino acids or
whatever.  I don't believe the Z0 had anything to do with it.
-- 
-Matthew P Wiener (weemba@sagi.wistar.upenn.edu)
Xref: sparky sci.physics:13092 sci.skeptic:14679 alt.folklore.science:3066
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Newsgroups: sci.physics,sci.skeptic,alt.folklore.science
Subject: Re: The dangers in microwaved food...
Date: 20 Aug 92 01:55:31 GMT
Article-I.D.: nuscc.1992Aug20.015531.7842
Organization: National University of Singapore

there are serious health risks in eating.
Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: Hubble constant?
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Mon, 17 Aug 1992 07:08:00 GMT

scip1061@nuscc.nus.sg (Marc Paul Jozef) writes...
>Dave, although you did not want to say it directly,
>you have chosen to reject the idea that the global
>metric of spacetime can be approximated by a
>Friedmann metric.

Nonsense. It can.

>                   So when using G(g) = T in cosmology
>-whatever the udealization for T- you tell us we are
>no longer allowed to assume g Friedmann.
>(You haggle about _exactly_ Friedmann. That is irrelevant;

The logic in your last post implicitly assumed _exactly_ Friedmann

>In answer to your last question, few matter distributions
>produce a pumpkin cosmology, especially if the pumpkin
>is parabolic and fanning out like a flower. I would
>say the only matter distribution resembling a pumpkin
>is a pumpkin itself.

Very funny. But in all honesty, I'm not 100% certain you're joking.

Dave Ring
dwr2560@zeus.tamu.edu
From: ag3l+@andrew.cmu.edu (Arun K. Gupta)
Newsgroups: sci.physics
Subject: Re: Facts and Values
Date: 23 Aug 92 08:01:14 GMT
Article-I.D.: andrew.QeZvN_O00VAwQ0q5AU
Organization: Physics, Carnegie Mellon, Pittsburgh, PA



Scott, the very fact that physics has not shown any need for soul,
afterlife, heaven and so on, and the tremendous success of science
have given cause for people to doubt the religions they once took
for granted.

One indication of how much the religious leadership envies and fears
this success is in the movements that purport to show that the Qu'ran
contains scientific predictions and that a grand unified field theory
can be found in the Hindu Vedas, and so on.
The intellectual respectability of religion as a way to look at
the universe is eroding rapidly, and this shows up in our value
systems.

-arun gupta
Newsgroups: sci.physics
From: jbaez@nevanlinna.mit.edu (John C. Baez)
Subject: Re: unitarity red herring
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Wed, 12 Aug 92 23:41:34 GMT

In article <mcirvin.713566546@husc8> mcirvin@husc8.harvard.edu (Mcirvin) writes:
>jbaez@nevanlinna.mit.edu (John C. Baez) writes:
>
>>It seems, by the way, that Sarfatti knows his transformation is unitary
>>and couldn't care less:
>
>I assume you meant "not unitary"...

Yes, I didn't get anything right in that post.

>>In article <BssCHF.JxB@well.sf.ca.us> sarfatti@well.sf.ca.us (Jack Sarfatti) writes:
>>>#2 The mistake you keep making is to take a fragmentary view. You keep
>>>saying that the matrix is not unitary. So what! I am using both Feynman
>>>rules
>>>from preparation to irreversible detections and this process is not unitary.
>>>If you
>>>want to describe the total behavior of my device then of course the matrix
>>>from
>>>start to finish is not unitary because of measurements!

>>[...] the nonunitarity of your process goes
>>against what I'd call "standard quantum mechanics" and a clear symptom
>>of that fact is that you claim that you can get faster-than-light
>>communication!  

>Your bias against collapse hypotheses is showing itself... :-)

It's not a bias, it's a justified distaste.  :-)

In any event, I now agree with others that the key bad thing about
Sarfatti's linear transformation is that it is not "local," i.e., it's
not a tensor product of two linear transformations, one on the Hilbert
space describing each subsystem. 

I wish he'd just run the experiment and see what happens.
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Newsgroups: sci.physics
Subject: Re: The End of Physics?
Date: 15 Aug 92 03:13:26 GMT
Organization: National University of Singapore

And you thought hporopudas was bad.
Newsgroups: sci.physics
From: jbaez@nevanlinna.mit.edu (John C. Baez)
Subject: Re: An easy problem in general relativity
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Wed, 12 Aug 92 23:56:25 GMT

In article <1992Aug12.060105.10373@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:
>JB: As you say, cosmic censorship is a "touchy-feely" kind of thing. And
>that is what I had in mind when I said that there is nowadays even less
>reason to believe in it.

Oh.  "Nowadays" made me think something new had been discovered.

>As for llamas etc coming out of naked singularities: how exactly does
>one prove this? 

See my recent paper, "Llamas from Naked Singularities".

>But anyway, I agree that strange things are likely in
>the vicinity of a naked singularity. But so what? What do you have
>against llamas?

Nothing, I just don't like them getting spewed out of singularities for
no good reason.  It would be a bummer to sacrifice causality in
CLASSICAL mechanics due to naked singularities and thus it is more
conservative to hope either for cosmic censorship or quantum effects to
do away with the singularities.  I don't really want to argue further
about this since it's just a matter of esthetics and too little is known
about these matters to declare anything impossible.

>Finally: what makes you say that quantum gravity is likely to do away
>with the singularities? Do people have specific reasons for thinking
>so, other than "quantum good, singularity bad"?

Yes.  First it is interesting to note that historically quantum
mechanics saved the day in two other situations where classical there
was singular behavior.  First, the ultraviolet catastrophe in the
classical approach to blackbody radiation.  Second, the appalling
tendency for classical hydrogen atoms to collapse in a brief time
emitting an infinite amount of radiation.  The second one is the one
more relevant here.  The classical atom is unstable and becomes
singular in a finite amount of time, but with quantum mechanics the
uncertainty principle (roughly speaking) saves the day by preventing
collapse.  

Second, and a much longer story, is the fact that there is a promising
approach to quantum gravity called the loop representation and there
seem to be no singularities there.  Of course other people have other
ideas about quantum gravity, e.g. string theory -- what's the latest
word on black holes in string theory?  (I'd seen some papers on stringy
black holes...)
From: dhg@sinix.UUCP (David Griffith)
Newsgroups: sci.physics
Subject: Is Space a continuum?
Date: 14 Aug 92 15:43:21 GMT
Organization: Primitive Software Ltd.

Is space a continuum? In other words, does General Relativity suitably
adjusted by Quantum Mechanics, treat space-time as infinitely
sub-divisible? If it's not, how does this affect the mathematics, eg
calculus which assumes deltas that tend to zero?

Dave Griffiths
From: davros@dogbox.acme.gen.nz (davros)
Newsgroups: sci.physics
Subject: Velocity of light in Ferro-Magnetic Materials
Keywords: Ferrite
Date: Mon, 17 Aug 92 22:37:46 NZT
Distribution: World
Organization: The Dawghaus BBS

Greetings fellow readers of sci.physics. I have a question for the 
materials peoples out there. I would like to know if there is a
reference book or a governing equation to tell me the refractive index of 
certain materials wrt to hysteresis curves I suppose. Basically I need to 
calculate the wavelength of an EM wave passing through a ferro-megnetic 
solid. Anyone out there have any clues or answers?

Please EMAIL responses to davros@acme.gen.nz

Thanks.
Steve.

davros at The Dawghaus BBS  ( +64 6 357-9245 )