HDTenEightyP/NetNews huggingface dataset:
From: hall@vice.ICO.TEK.COM (Hal Lillywhite)
Newsgroups: sci.physics
Subject: Re: Blue Sky
Date: 22 Jul 92 22:34:32 GMT
Organization: Tektronix Inc., Beaverton, Or.

In article <9930@sun13.scri.fsu.edu> jac@ds8.scri.fsu.edu (Jim Carr) writes:

...
>George did that routine before blue-corn became popular enough to 
>show up as corn flakes as well as tortillas, or squid-ink pasta made 
>it into american grocery stores.  Interesting that there are blue birds 
>and flowers but not blue animals; where is a biologist when we need one! 

And I find it peculiar that although there are blue birds, there are
no blue raptors that I know of.  Can you imagine the advantage a sky-
blue hawk would have?  His prey would have a very difficult time seeing 
him until it was too late.  I wonder why such an obvious advantage 
seems not to have developed.
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Newsgroups: sci.physics
Subject: Re: ZERO Nuclear impact (was: Is car pooling for real? etc)
Date: 25 Jul 92 19:26:03 GMT
Organization: University of Virginia

In article <1992Jul25.183038.5345@murdoch.acc.Virginia.EDU> gl8f@fermi.clas.Virginia.EDU (Greg Lindahl) writes:
>In article <1992Jul25.180106.5023@murdoch.acc.Virginia.EDU> crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:
>
>>     Gee, Greg.  Once again you insist on implying that these
>>     objections have been *successfully* addressed rather than
>>     making the arguments yourself.  Is this simply laziness, or
>>     is it a realization that the counterarguments are weak? 
>
>I'm sorry Dale, but I don't claim to be an expert on hydrogen storage
>in metal lattices. I'm just pointing out references in the literature.
>That's how science gets done, you know, by publishing in the
>literature, not by arguing on Usenet. If you think that reading the
>literature is laziness, then I can't help you.

     Weak counterargument.  Economics comes in to the storage of
     hydrogen in this fashion.  It would be much cheaper just to 
     pull methane out of the ground (or crude oil for that manner)
     than to use solar of any form to separate water to be 
     transported around in hydrogen-containing metals.  In fact
     if one insists on doing things this way, it is cheaper to 
     build a large nuclear plant to do the electrolysis, eliminating
     solar entirely.

>>     P.S.  exploding hydrogen is a wonderful topic for this newsgroup.
>
>If you're curious about the results, they have developed hydrogen
>storage containers that can be punctured, crushed, and otherwise
>dismembered (i.e. shot with high-power rifles) without exploding. I'm
>sorry that you can't take a few minutes out of your busy schedule to
>read about it.

     For my work, we'll have a D2 container that will not be crushable
     even if one dropped the loading crane on it.  That does not
     make it viable and economically feasable for using in 
     a 'hydrogen economy'.

>Again, I'd suggest another newsgroup if you wish to continue your
>massive flamewar on these issues.

     You may continue the flamewar you started in any group you feel
     necessary.  Usually, I'll just stick to making and rebutting 
     arguments presented.

                                  dale bass

--
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926
From: kiviat@oasys.dt.navy.mil (Brian Kiviat)
Newsgroups: sci.physics
Subject: Re: density of commonly used materials
Date: 31 Jul 92 12:12:49 GMT
Reply-To: kiviat@oasys.dt.navy.mil (Brian Kiviat)
Followup-To: sci.physics
Organization: Carderock Division, NSWC, Bethesda, MD

In sci.materials, sundar@fiber-one.ai.mit.edu (Sundar Narasimhan) writes:
>Hi, I am interested in finding out the densities (ranges) of commonly used
>materials (starting from things like Aluminium, Steel, Wood etc. to


Look for the book "Marks Standard Handbook for Mechanical Engineers"
It will have all that you desire.

Brian
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Aristotle and the Modern Physicist
Date: 27 Jul 92 21:08:13 GMT
Article-I.D.: husc8.mcirvin.712271293

aephraim@physics.Berkeley.EDU (Aephraim M. Steinberg) writes:

>Anyway, I'm not convinced that the center of mass of a system can be 
>different in two parts of a coherent superposition.  

Trivially, it can.  Just look at the different position
eigenstates of the expanding wavefront of an electron.  As
for magnifying the effect by using a Schrodinger's cat type
apparatus to shove weights around, I think your objection
about the center of mass is sound.
 
>I'd be slightly
>more inclined to believe that you could superpose two distributions with
>different QUADRUPOLE moments or something like that, affecting more subtle
>things than the simple force on a nearby object. 

The aftermath of a cat-box experiment probably shouldn't be
called a *coherent* superposition in the modern sense of the
term, but you could indeed rig one so that the quadrupole
moment would depend on the outcome.  Just replace the hammer
above the poison jar with a mechanism that pushes apart two
large weights when the decay occurs.  This *would* affect the
fall of a nearby object, if it's close enough.  Imagine that
it's near the end of the box where one of the weights ends up
in the event of a decay.

>The reason I really respond is just because it's amusing that you come
>up with this particular example.  I wonder if you're aware that it's exactly
>what Aharonov uses in one of his latest proposals?  In conjunction with his
>theory of "weak measurements," he uses such a system, in which the rate of
>a clock depends on the state of the mass shell and can thus be placed in
>a superposition state, to create a time machine.  

It is quite an ingenious proposal.  Now that you mention it,
let me correct a blatant error in the recent Scientific
American article about measurement theory:  the "time machine"
is not the usual variety in which one can travel into the
past and violate causality.  Rather, it's a device for
reversing the time evolution of a system, returning it to
a younger state.  It's not so much a time machine as a
kind of rewind button.

-- 
Matt McIrvin  mcirvin@husc.harvard.edu
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: scientific literature
Date: 29 Jul 92 18:21:09 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 <4535@dove.nist.gov>, gilligan@bldrdoc.gov (Jonathan Gilligan 303-497-3861) writes...
> 
>Then is Reviews of Modern Physics not part of the scientific
>literature because debates are not published there?
> 

The review journals are a rather different thread of scientific discussion
than that which is contained in the weekly or monthly journals.  They 
represent attempts at synthesis of fairly well established material, providing
the reader with organized references into the primary literature, and authors
with a way of providing a single reference into the literature in future
primary journal articles.  

Although they play an important role in the ongoing scientific discussion,
they are not primary literature and as such are subject to somewhat different
standards.  

But they *are* part of the scientific literature - they present material 
in a new (synthetic) light, assuming that the topic and author were both
well chosen - and contribute to the development of the field.

On the other hand, Scientific American, being intended for lay consumption,
does not generally present material in a way that it has not already been
seen somewhere else.  Just with better illustrations.

-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: vgurarie@phoenix.Princeton.EDU (Victor V. Gurarie)
Subject: Re: Defining Photons
Originator: news@ernie.Princeton.EDU
Keywords: Relating photons E=MC^2 criticism
Organization: Princeton University
Distribution: na
Date: Mon, 27 Jul 1992 03:32:11 GMT

In article <26JUL199218561022@zeus.tamu.edu> dwr2560@zeus.tamu.edu (RING, DAVID WAYNE) writes:
>sichase@csa2.lbl.gov writes:
>>>Notice that masslessness have nothing to do with these questions.  It a matter
>>>of spin, not mass.  Massive bosons, such as the W or Z, if we were able 
>>>to make enough of them to produce a semiclassical state, would behave much
>>>like photons, not at all like electrons.  
>
>jac@ds8.scri.fsu.edu (Jim Carr) writes...
>>And it also follows that large numbers of neutrinos would act more like 
>>electrons than photons, despite the fact that they are massless. 
>
>Hmmm... I disagree with you both :-)
>
>I think anything with a charge will appear as a particle in the classical
>limit, whether boson or fermion. Like a W in a cloud chamber. And anything
>which interacts as weakly as a neutrino would behave like a wave.
>
>Anyway, I wonder if our non-scientist friend knows that electrons are really
>massless, and that they only _look_ massive because of thier interaction
>with the higgs.
>
>Dave Ring
>dwr2560@zeus.tamu.edu


   I have a strong feeling that one would NEVER be able to produce a
semiclassical state of W or Z particles. They are so massive that they
would decay BEFORE we could form a semiclassical state. Also their
characteristic length is R=1/M, M - mass. It is masslessness of the photon
which makes it behave like a wave. (and its stability). Anyway, 
all that dispute is pointless since all we know that one and the same
particle can behave both as a wave and as a particle! (an electron, for
example).
Newsgroups: sci.physics
From: holger@esfra.sub.org (Holger Stegemann)
Subject: velocity calculation
Organization: Ebert & Stegemann GmbH; Frankfurt/Main
Date: Wed, 29 Jul 92 13:36:42 GMT

Could someone help me with this problem?

Given a constant acceleration for a spaceship, how can I calculate the
velocity when it comes near c ?

For example, if a spaceship accelerates with 1 g for 1 year, what is it's
velocity? I couldn't find a formula for it.

Thanks,
Holger.
-- 
-------------------- holger@esfra.sub.org -------------------
Holger Stegemann                    100016.633@compuserve.com
Staedelstr. 8, W-6000 Frankfurt 70  Tel. 069 / 619047 (Voice)
Newsgroups: sci.physics,sci.astro,sci.philosophy.tech,talk.religion.misc
From: billn@hpcvaac.cv.hp.com (bill nelson)
Subject: Re: Structure of Time
Organization: Hewlett-Packard Company, Corvallis, Oregon USA
Date: Wed, 29 Jul 1992 19:06:46 GMT

psyrobtw@ubvmsb.cc.buffalo.edu (Robert Weiss) writes:
: In article <1992Jul28.175239.10109@hpcvaac.cv.hp.com>, billn@hpcvaac.cv.hp.com (bill nelson) writes...
: 
: >You were asked a number of times to take your postings somewhere else
: >where they would be appreciated. You ignored the requests - you deserve
: >to suffer the consequences - whatever they may be.
: 
: 		Try to keep this in perspective.
: 
: 		You're talking about someone losing their job and 
: livelihood as being less important than you having to hit the spacebar.

I posted before that I thought a person losing their job over this was 
an overly extreme reaction.

However, I wonder how well the person is doing their job, if it can be
threatened by such a minor thing.

Before anyone asks - I was not one of those that wrote to his employer. I
also believe that using the 'n' key is the most appropriate response if you
do not wish to read a posting.

However, I still stand by what I said. A person should be willing to accept
the consequences for their actions - even if they are more harsh than they
expected.  When people complained and are ignored - I am not surprised that
they went further and contacted the employer. The person making the postings
should be intelligent enough to realize this could happen.

Bill
Newsgroups: sci.physics
From: metares@well.sf.ca.us (Tom Van Flandern)
Subject: Re: Twin Paradox
Organization: Whole Earth 'Lectronic Link
Date: Wed, 22 Jul 1992 05:39:12 GMT


aguirre@wigner.physics.upenn.edu (Anthony Aguirre) writes:

>    What you're saying is no different than complaining about the first half
> of the standard twins paradox: If the first twin leaves for AC at 99% the
> speed of light, he feels that 7 months have passed, whereas the twin on
> earth would claim that 4 years had passed.  But why not assume that the
> first twin stayed still, the earth moved away at 99% c, thus the earthman
> aged 7 months and the traveller aged 4 years?  This is basically the same
> as the "paradox" you are pointing out.
>
>    The problem, however, is that the twins cannot compare ages until they
> have returned to the same reference frame. The asymmetry occurs when the
> traveler turns around and returns to earth.  If, somehow, the earth (and
> AC) were to turn around so that the earth returned to the traveler, then it
> would turn out that the traveler was younger than the earthman.  Thus,
> symmetry.

     It is not necessary for one of them to turn around or accelerate to make
this comparison.  That just confuses the issue, because then people start to
think that turning around has something to do with who ages how much.  It
does not.  The differential aging occurs in a simple one-way trip without
accelerations, as should be evident in this example.  And when all four
encounters are examined, all possible age comparisons become possible by
direct (not remote) observation.

>    In your example, one of the two reference frames would have to change in
> order for both reference frames to become equivalent and allow a meaningful
> comparison of ages.  Depending on which frame changes, one of the twins
> would end up older than the other in a way similar to the standard twins
> paradox.

     No, meaningful comparisons can be done at each encounter event.
Eventually all combinations are compared.

>    You might object "well, why not compare the ages from a distance."  For
> example, the traveler, upon reaching AC, could send a message home at the
> speed of light, saying "it took me 7 months (my time) to get here."  The
> earth would receive this message four years after it was send (in the
> traveller's frame.)  But his doesn't mean four years in earth's frame.  The
> key to the twins paradox (as in all SR) is being very careful about exactly
> which measurements are being taken, and in which frame, etc.

     See my new posting with the resolution of the paradox.  -|Tom|-

-- 
Tom Van Flandern / Washington, DC / metares@well.sf.ca.us
Meta Research was founded to foster research into ideas not otherwise
supported because they conflict with mainstream theories in Astronomy.
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Magnetic lenses
Date: 28 Jul 92 20:09:36 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 <ceRLP2O00WB78ZLEYJ@andrew.cmu.edu>, gr1c+@andrew.cmu.edu (Greg Howard Rhodes) writes...
>Well, as a senior undergraduate physics student, I feel that I should know
>the answer to this, but my optics are not all they should be...(and with the
>GREs coming up really soon, too...)
> 
>Anyway, I just got glasses. Being able to see and all is great, but I started
>wondering about alternatives. Now, sure there all of the contact lenses and
>the like, and maybe even lenses designed to actually _fix_ your vision. But
>I was thinking about something a bit more esoteric.
> 
>Would it be possible to use a strong stationary E and/or M field to bend
>light in such a way to mimic an eyeglass? And if it would be possible, how
>strong would the field have to be? (and, from a consumer standpoint, how 
>small could it be made?

Photons, being uncharged, are not easily affected by stationary EM fields.
There is a nonlinear effect that is very weak and not useful for your
purpose.  So the basic answer is that it would not be possible in the 
way you describe.  However...

If you have ever used an image intensifier tube in a region of stray 
magnetic fields, then you have seen that the field produces a distortion
in the output image.  This is because the image is actually flying through
the tube as electrons emitted from a surface with a low work-function.
The final image is only reconstructed when the electrons hit the photocathode.
If there is a stray field (at least in "first generation" tubes) the
image is distorted.  So this might provide a mechanism by which you could
"predistort" the incoming image in such a way as to compensate for the
distortion which your own eyes will impose before your brain gets the signal.

Regards,

-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
From: paj@uk.co.gec-mrc (Paul Johnson)
Newsgroups: sci.physics
Subject: Re: Blue hawks (was Blue Sky)
Date: 27 Jul 92 15:43:14 GMT
Reply-To: paj@uk.co.gec-mrc (Paul Johnson)
Organization: GEC-Marconi Research Centre, Great Baddow, UK

In article <10018@vice.ICO.TEK.COM> hall@vice.ICO.TEK.COM (Hal Lillywhite) writes:

>And I find it peculiar that although there are blue birds, there are
>no blue raptors that I know of.  Can you imagine the advantage a sky-
>blue hawk would have?  His prey would have a very difficult time seeing 
>him until it was too late.  I wonder why such an obvious advantage 
>seems not to have developed.

Because it doesn't work.  No matter what you paint the underside of an
aircraft, it still gives you a silhouette against the sky because the
sky is brighter than the illumination of the underside of the
aircraft.

Experiments in camauflage have been done which involve putting lights
on the underside of aircraft in order to match the sky.  This works,
and was (as I recall) used in the second world war by anti-submarine
aircraft.  Then the invention of radar made the whole matter moot.

Active illumination is not an option available to eagles.

Paul.

-- 
Paul Johnson (paj@gec-mrc.co.uk).	    | Tel: +44 245 73331 ext 3245
--------------------------------------------+----------------------------------
These ideas and others like them can be had | GEC-Marconi Research is not
for $0.02 each from any reputable idealist. | responsible for my opinions
From: andrew@rentec.com (Andrew Mullhaupt)
Newsgroups: sci.physics
Subject: Re: Blue Sky
Date: 23 Jul 92 21:12:21 GMT
Distribution: na
Organization: Renaissance Technologies Corp., Setauket, NY.

In article <1992Jul22.154233.21594@linus.mitre.org> m14494@mwvm.mitre.org (Mike White) writes:
>Andrew Mullhaupt writes:
>> Why is the sky blue?
>
>You'll get lots and lots of answers, and I'll bet my tenure that not one 
>of them will address the question "Why?"; they'll all address the question 
>"How?".  They'll go on and on about scattering of light from Nitrogen 
>molecules, but the question of "Why?" is much harder. 

Well, I don't mean to be too directive about it - I want to know what
physicists actually say when you ask them that question. If I can find it,
I will post what my prediction was (posted in another group recently) and
a summary of the net's responses.

Later,
Andrew Mullhaupt
Newsgroups: sci.physics
From: braham@physics.ubc.ca (Stephen Braham)
Subject: Re: Quantum Cosmological Boundaries and Determinisim?
Organization: University of British Columbia, Vancouver, B.C., Canada
Date: Wed, 22 Jul 1992 20:08:41 GMT

<MRG3@psuvm.psu.edu> writes:
> [some stuff deleted]

>A variation of this scheme included two density operators for both initial and
>final conditions. This seemed to be an attempt to remove the apparent
>introduction of time asymetry by hand. I hope the proposal has died a quiet and
>painless death. :)

HEY! <grin> It's quite a useful thing to do- it's more of an example
than anything though. The idea it to try to understand what we may
or may not get out of, say, a sum-over-histories, formulation of
quantum cosmology. There are ways of formulating the path integral
in such as way that you have, effectively, both past and future
conditions. You can simulate the effect in old-fashioned Hamiltonian
quantum mechanics by adding the final density matrix in. It IS useful
in certain circumstance, though. Tony leggett and others (including
my boss :)) have pointed out that you CAN do time-symmetric experiments
and you need this insertion of final conditions to get the right result.
In this situation, you have no density matrix at intermediate times
that can describe probabilities- you NEED the final condition part.
Tony's hoping to verify this with his squid experiments, of course.
Hmmmm, the reference part of this posting now has three members of
the same PhD graduating class in it <chuckle>. Go lions! <grin>

>-mike gallis
>mrg3@psuvm.psu.edu

			Steve

--
| Name: Stephen P. Braham | Perversion: Quantum Cosmologist|
| Hangout: UBC physics    | Signature:  Euclidean          |
|          Vancouver, BC  |--------------------------------+
|          Canada         | E-mail: braham@physics.ubc.ca  |
Newsgroups: sci.physics
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: ZERO Nuclear impact (was: Is car pooling for real? etc)
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Mon, 27 Jul 92 21:49:42 GMT

In article <1992Jul25.183038.5345@murdoch.acc.Virginia.EDU> gl8f@fermi.clas.Virginia.EDU (Greg Lindahl) writes:
>In article <1992Jul25.180106.5023@murdoch.acc.Virginia.EDU> crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes:
>
>>     Gee, Greg.  Once again you insist on implying that these
>>     objections have been *successfully* addressed rather than
>>     making the arguments yourself.  Is this simply laziness, or
>>     is it a realization that the counterarguments are weak? 
>
>I'm sorry Dale, but I don't claim to be an expert on hydrogen storage
>in metal lattices. I'm just pointing out references in the literature.
>That's how science gets done, you know, by publishing in the
>literature, not by arguing on Usenet. If you think that reading the
>literature is laziness, then I can't help you.

Dale was not implying that science gets done on usenet; it quite
obviously doesn't.  Nonetheless it is a tradition on usenet to back up
ones statements when it is requested to do so.  This is crucial because
all usenet is is a bunch of invisible people chatting, many of whom have
never heard of each other, so that argument by authority is worthless.
If one knows articles that say X, but are not in a position to argue for
X oneself, it's best not to assert "X" but simply to say "I read X in
such-and-such place but I am not competent to evaluate this article."
From: jtrsmith@garnet.berkeley.edu ()
Newsgroups: sci.physics
Subject: Off-center ensemble average
Date: 24 Jul 1992 07:58:43 GMT
Organization: University of California, Berkeley
Distribution: world
NNTP-Posting-Host: garnet.berkeley.edu
Originator: jtrsmith@garnet.berkeley.edu

Hi,
Does anyone know "off-center ensemble average"?
If yes, could you explain it to me and give me some reference?
Thanks.
(please reply to this account if possible.)
Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: Structure of Time
Followup-To: sci.physics
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Fri, 31 Jul 1992 02:25:00 GMT

zlsiida@fs1.mcc.ac.uk (dave budd) writes...
>Yes - maybe a netter in finland should be calling the child protection 
>people?

Ouch. Please, please don't say things like that. I admit it is unlikely
that anyone will take you seriously, but even a chance is too much.

Dave "hindsight is 20/20" Ring
dwr2560@zeus.tamu.edu