HDTenEightyP/NetNews huggingface dataset:
From: jac@ds8.scri.fsu.edu (Jim Carr)
Newsgroups: sci.physics
Subject: Re: Converting the masses
Date: 26 Jul 92 19:43:44 GMT
Reply-To: jac@ds8.scri.fsu.edu (Jim Carr)
Organization: SCRI, Florida State University

In article <1992Jul22.193837.18095@sfu.ca> palmer@sfu.ca (Leigh Palmer) writes:
>In article <9868@sun13.scri.fsu.edu> jac@ds8.scri.fsu.edu (Jim Carr) writes:
>
>>It should be added that I do not know of any physicist who works wiht 
>>relativistic kinematics -- either nuclear physicists, astrophysicists, 
>>or particle physicists -- who use this first definition.  There is the 
>>variable W = sqrt(s), where s is one of the Mandelstam variables, known 
>>as the total energy that can be used for such purposes. 
>
>Well, Jim, now you do. In the context of those disciplines the conventional
>definition of mass is *now* that which you advocate. I surely hope that you
>do not use that definition in teaching elementary physics, however, which 
>is how some of us astrophysicists make our livings. In order to illustrate
>my point, do you claim that a lump of condensed matter has a the same mass
>as the sum of the masses of its elementary constituents? Of course you don't.

Oh oh, of course not.  I even use the proton mass (gasp) when working out 
the kinematics for a proton despite the fact that its constituents have 
very little mass (in the sense of the current quarks one would use in an 
ab initio calculation of the proton mass).  

The risks of living a skizo life where sometimes one works at calculating 
the mass of something from the masses and binding energies of its 
constituents, and other times one treats the object as "elementary" 
for the purposes of calculating other things...  Thanks for the reminder!  

I guess I should say that no one uses the first definition when working 
out the kinematics of objects (composite or not), but that one has to 
be careful when speaking about other aspects of the prescriptions used 
to accomodate language and physics.  Of course the mass of a composite 
object should be the rest energy if you assume that a composite object is 
governed by the relativistic energy equation.  This is not the same as 
the first definition, where the mass depends on the reference frame, 
but there are some common elements in the two pictures.  Certainly 
one can compute correct answers either way, but the second method is 
simpler and more easily applied.

--
J. A. Carr                                    |  "The New Frontier of which I  
jac@gw.scri.fsu.edu                           |  speak is not a set of promises
Florida State University  B-186               |  -- it is a set of challenges."
Supercomputer Computations Research Institute |   John F. Kennedy (15 July 60)
Newsgroups: sci.physics
From: dwr2560@zeus.tamu.edu (RING, DAVID WAYNE)
Subject: Re: Aristotle and the Modern Physicist
News-Software: VAX/VMS VNEWS 1.41    
Organization: Texas A&M University, Academic Computing Services
Date: Sat, 25 Jul 1992 01:14:00 GMT

matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes...
>                                       But I do claim that many people
>think of gravitation as an "interaction". Which it is NOT; this being
>the main point of GR.

So what does the gravitation constant measure?

>                                  To ask, "why does the Earth go around
>the Sun?" is precisely analogous to asking Newton or Galileo why a free
>particle moves in a straight line at constant speed.

As Feynman was so fond of pointing out, Newton didn't know the answer.

>                                                           "Gravity" was
>all a mistake, resulting from our ignorance of spacetime curvature. How
>does one quantize a mistake?

Consider a Schroedinger's Cat apparatus where the box is large and contains
a mass distibution instead of a cat, and a mechanism to alter the mass
distribution if the nucleus decays. After a time the mass distribution
will be in a superposition of states. How will a test particle outside the
apparatus know how to fall?

Equivalently, does curvature couple to the energy momentum tensor (an operator)
or to its expectation value, or something else?

Dave Ring
dwr2560@zeus.tamu.edu
Xref: sparky sci.physics:11916 alt.fan.dale-bass:5
From: gsh7w@fermi.clas.Virginia.EDU (Greg Hennessy)
Newsgroups: sci.physics,alt.fan.dale-bass
Subject: Re: "What's New" July-24-1992
Date: 29 Jul 92 03:51:38 GMT
Followup-To: alt.fan.dale-bass
Organization: University of Virginia

In article <1992Jul29.032824.6226@murdoch.acc.Virginia.EDU>
crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes: 
#     Do they?  I'm glad to hear that they will now oppose SSC
#     on the grounds that it is mostly engineering.

False. We ain't building the damn thing to learn about engineering, we
are building it to learn about science. The amount of new engineering
was kept to a minimum. The same is not true for SSF.

#     At least be consistent.  Is it the 'science-thing' or is it
#     the money?  Or is it both, in which case they should vehemently
#     oppose astrology AND the SSC.

Well, the APS thinks that the SSC is good science, so you can't
logically expect them to oppose it on those grounds. Astrology doesn't
get funded by the federal government, so they don't bother much with
it. 

#     I don't see the AMA opposing SSC on the grounds that it will
#     not be a boon to cancer cures as claimed.  I don't see  
#     AIAA or civil engineering societies opposing the SSC on 
#     the grounds that it is too expensive to be justified by
#     great advances in engineering, as has been claimed.
#     And yet the APS seems to object to the SSF on the grounds that
#     there is 'not enough science' to justify the project.  One can
#     only think that this is because they are worried about their
#     parochial funding.

Earth to Dale. The primary purpose of the SSC is not to cure cancer,
or learn engineering. The primary purpose is to do science.

I guess the Dale Bass method of science is to accuse everyone with a
different opinion to be unethical.

followups to alt.fan.dale-bass, which means that i'm sick of this
--
-Greg Hennessy, University of Virginia
 USPS Mail:     Astronomy Department, Charlottesville, VA 22903-2475 USA
 Internet:      gsh7w@virginia.edu  
 UUCP:		...!uunet!virginia!gsh7w
Newsgroups: sci.physics
From: mwj@beta.lanl.gov (William Johnson)
Subject: Re: Radionuclide Half-Lives
Summary: Maybe an FAQ entry? 
Organization: Los Alamos National Laboratory
Distribution: na
Date: Fri, 24 Jul 1992 19:47:33 GMT

In article <24761@dog.ee.lbl.gov> sichase@csa3.lbl.gov writes:
>For nuclei which decay by K capture, the decay rate is sensitive to the
>electronic structure of the atom.  This is obvious, because any capture
>matrix element will have to include the electron's wave function.  So if
>you take such an atom and bind it in a molecule so that it's electronic
>orbitals are perturbed, you affect the decay rate of the nucleus.
>
>You can look up the details in Segre's book _Nuclei and Particles_.  The
>effect has been experimentally verified.  Although I don't know if it has
>ever been done, you can easily imagine that very high pressures will also
>change the decay rate of a solid lump of such an element, for the same 
>reasons.

It's been done, for the astrophysically-important K-capturer beryllium 7.  Bill
Bassett's group at the University of Rochester (geochemists, not 
astrophysicists) did some work on this in the early 1970s, by which time it was
already a well-known phenomenon.  There are a few other cases that have been
reported in the literature, notably holmium-163, an *N*-shell capturer that is
particularly sensitive to environmental effects and again of astrophysical
interest as a result.

I have no idea what the original poster's "invention" is, and to put it mildly,
I am suspicious of it.  The broader question of environmental perturbation of
radioactive decay arises here (and also in sci.chem) every now and then; maybe
it would be a useful thing to add to the FAQ list.  I may try to put something
together that fits the bill.  In the interim, the standard (if rather dated)
review article on the subject is G. T. Emery, "Perturbation of Nuclear Decay
Rates," Annual Review of Nuclear Science vol. 22, pp. 165-202 (1972).  (I told
you it was rather dated ...)  Maybe the original poster should read this paper
and find out if the "invention" has been anticipated. :-) 1/2

-- 
Bill Johnson				| "This is a bit complicated, so let
Los Alamos National Laboratory		| me explain it backwards."  (first
Los Alamos, New Mexico USA		| line of a memo from a fellow Los
!cmcl2!lanl!mwj (mwj@lanl.gov)		| Alamos physicist who will go unnamed)
Newsgroups: sci.physics
From: tordm@vand (Tord Malmgren)
Subject: Re: Physics joke 
Reply-To: TordM@VanD.PhySto.SE
Organization: Department of Physics, University of Stockholm -- Sweden
Date: Tue, 21 Jul 1992 17:27:48 GMT

In article <ph3.711674796@unixg.ubc.ca>, ph3@unixg.ubc.ca (Michael Hamilton (phys 306)) writes:
>Q. Three photons are playing musical chairs. When the music stops, which photon
>is "out"?
>
>A. Photons can't play musical chairs, they're bosons. 

 this reminds me of a fun question I once heard... 

 "What is the speed of time?"
 100% ??? "10X faster than the speed of love?" -- Meat Beat Manifesto




---------------+--------------------------------
 Tord Malmgren | InterNet: TordM@VanD.PhySto.SE | These opinions are my own,
               | BITNet  : TordM@SESUF51        | and NOT of this department!
---------------+--------------------------------
 Department of Physics, University of Stockholm 
Newsgroups: sci.physics
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Defining Photons
Date: 27 Jul 92 20:13:58 GMT
Distribution: na
Organization: Rutgers Univ., New Brunswick, N.J.

Scott Chase writes:
>In principle it *is* possible to produce enough of them [W's] in short enough
>a period of time to produce such a state [semiclassical].  It just seems 
>unlikely that anyone will apply for NSF funding to do so in the near future.

What I want to know is, anybody out there building a W-laser?  [WASER?]

>> It is masslessness of the photon
>>which makes it behave like a wave. (and its stability). Anyway,
>
>Once again, this is completely false.  Rather than repeat ...
> ... semiclassical limits of quantum fields.

Actually, I think it's within the realm of elementary quantum
mechanics to demonstrate that bosons, any bosons, tend to behave like
[classical] waves that obey the superposition principle.  For example
the Hanbury-Brown and Twiss interferometer can be explained by looking
at boson statistics, or just with plain vanilla E & M.  I believe
there is a discussion of this remarkable instrument in Baym's
Lectures on QM.  (My QM prof said that H-B and T published a
classical explanation of their device first, and most people
assumed that it _had_ to be a quantum effect and they had just done
something wrong in their derivation.)

Ben Weiner
bosophysicist
From: whit@milton.u.washington.edu (John Whitmore)
Newsgroups: sci.physics
Subject: Re: Destroying the Earth
Date: 29 Jul 92 04:59:48 GMT
Organization: University of Washington, Seattle

In article <1992Jul28.044315.24255@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:

>To what radius would we have to compress the Earth in order to form a
>black hole? 

	The condition (here done classically, which is WRONG) is
that the binding energy equals the 'kinetic energy' of a mass moving
at the speed of light,

	GMm    mc^2
       ----- = -----
         Rs      2

and since we know GM/Re^2 is the surface gravity, 9.8 m/s^2 at Re=6.4e6 m,
it follows that

	Rs = 9e-3 M (yep, that's nine millimeters)

I seem to recall that this calculation is off by a factor of two,
but I don't recall which way the factor goes.  The simple classical
model gets the details wrong, but has the right scaling (GM/c^2).

	John Whitmore
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: What would a Photon be IF...
Date: 21 Jul 92 14:45:45 GMT
Article-I.D.: husc8.mcirvin.711729945

cescript@mtu.edu (Charles Scripter) writes:


>Here's a QED puzzler for you.  Suppose we examine the a free photon
>using Feynman diagrams:

[photon propagator with one-fermion-loop correction]

>Can these contributions be viewed as actual processes, or do we
>construe them be merely mathematical models?  

A fine thing to do a lot of thinking about.  I think of them as
terms in a perturbation expansion of what is really a continuous
process: the EM field is excited and it causes some collateral
excitation of the charged matter fields as well.  The Feynman
diagrams are a calculational device to get the outcome of the
continuous process to nth order.  

>This second order
>correction could be viewed as "photon decay", followed by an immediate
>recombination.  

I was, of course, using the usual definition of "particle 
decay" as a situation in which the decay products last "forever," but
as John Baez pointed out ominously a while ago, if we detect them, they
haven't lasted forever.  

Which implies another puzzler:  Are visible photons virtual?  What does 
this imply for causality-- since, after all, virtual photons don't have
to be *exactly* on their light cones?  I know that this doesn't
actually destroy causality, but I've never seen a very lucid explanation
of why not.  Any takers? 

>Although energy-momentum conservation is violated, we
>are allowed to violate this on quantum time scales (how short is "short"?).
>Energy and momentum are clearly conserved on macroscopic time scales.

No!  No!  Energy-momentum is *always* conserved!  It's the laws of
motion that are violated!  :)  (The two views are really equivalent,
and correspond, respectively, to old-fashioned and covariant perturbation
theory.)
 
-- 
Matt McIrvin, grad student, Dept. of Physics, Harvard University
mcirvin@husc.harvard.edu      mumble mumble mumble mumble mumble
Newsgroups: sci.physics
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: mind-numbing gedankenexperiment
Date: 24 Jul 92 20:41:39 GMT
Distribution: na
Organization: Rutgers Univ., New Brunswick, N.J.

>>And I'm the King of England.
>>Ben Weiner
>>("Weiner" is not a particularly Hanoverian name.)
>
>That's OK.  "Hanover" is not a very British city.  But that never stopped
>anyone.

Scott, you set the distribution to "na," so no Royalists (except
Canadians?) will bring this up, but the Royal Family of England
is almost wholly German, being descended from the Hanoverian dynasty
(Prince Albert of Saxe-Coburg or something equally dreadful, 
sausage-eaters every last one).  What does this have to do with
physics?  As much as the quantum pooper-scooper or whatever it was
that began this thread.
From: gl8f@fermi.clas.Virginia.EDU (Greg Lindahl)
Subject: Re: ZERO Nuclear impact (was: Is car pooling for real? etc)
Organization: Department of Astronomy, University of Virginia
Date: Sat, 25 Jul 1992 18:30:38 GMT

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.

>     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.

Again, I'd suggest another newsgroup if you wish to continue your
massive flamewar on these issues.
From: mdturner@riker.acs.calpoly.edu (M Turner)
Newsgroups: sci.physics
Subject: Re: The Bubbles
Date: 28 Jul 92 21:11:39 GMT
Reply-To: mdturner@riker.acs.calpoly.edu
Organization: Cal Poly State University, San Luis Obispo

Ching-Long Wu (PHYS U790315) writes
>  I am quite interested in the behavior of the bubbles that floating
>on water's surface. I have several questions:
> 1. What's the shape of it? Is it a perfect semi-sphere?

If the water surface were stationary it would have to be a perfect hemisphere.   
The base of the bubble would change to eliptical as the water's motion  
incresed.  Size depends on the radius of the bubble (the volume of gas) in  
comparison to the curvature of the wave. 

> 2. Why does it break? And what's the machanism of it's breaking?

I say the curvature of the water controls the machanism.  If the bubble in on  
a crest of a wave tension in the membrane will pull the ends and snap it off  
the surface.  If the bubble is in a trough too much pressure builds in the  
bubble and it pops, it gets pinched by the water.
 
> 3. I suppose there are some relation between a bubble's 'life' and 'size'.
[deleted exp set up]

Most likely for a fixed volume of gas the buble grows until the film gets  
stretech too thin, then pop.

> 4. What if the bubbles are floating in the air? If there is no gravitation,
> will them break?

I'd say air pressures in odd ball coinfigurations, like water, will pinch or  
squeez the buble.

>    I hope you are also interested in these questions...

very much so

Mark Turner
mdturner@riker.acs.calpoly.edu
Xref: sparky sci.physics:11972 sci.astro:8448 sci.philosophy.tech:2903 talk.religion.misc:12973
From: terry@venus.sunquest.com (Terry R. Friedrichsen)
Newsgroups: sci.physics,sci.astro,sci.philosophy.tech,talk.religion.misc
Subject: Re: Structure of Time
Summary: nobody deserves to have his job threatened
Keywords: babbling   physics   net.idiots
Date: 29 Jul 92 18:24:35 GMT
Followup-To: sci.astro
Distribution: na
Organization: Sunquest Information Systems, Tucson

In article <1992Jul28.211456.25821@hpcvaac.cv.hp.com> billn@hpcvaac.cv.hp.com (bill nelson) writes:
>sichase@csa2.lbl.gov (SCOTT I CHASE) writes:

>: I wonder what someone could have said to his employer, that if he
>: was otherwise satisfied with his performance could have put his job
>: in jeopardy?

>I also wonder. I think that a request by the employer to restrict the
>posting to such groups as alt.mythology or alt.paranormal would be more
>reasonable. 

Unfortunately, there are a few complete and utter fools who read the news
and think that their obligation is to make life miserable for as many other
people as possible.

In one case I am familiar with, a net.idiot called a poster's employer and
threatened to precipitate an FBI investigation if the employer didn't take
immediate steps to prevent the poster from using the net!  Other really nice
acts, such as threatening letters to CEOs (who often have no concept of what
the net is in the first place), or letters to the site postmaster or system
manager demanding the user's removal from the system, also occur.

I wish to state, categorically and for the record, that *all* such activity
is utterly reprehensible and totally uncalled-for!  If anyone reading this
posting is one of the net.idiots who contacted what's-his-name's employer,
GO AWAY!  The net doesn't want you, and the net *certainly* doesn't need you.

We're all representing ourselves and only ourselves in our postings.  Our
employers have nothing to do with it.  If the few net.idiots would only
understand that, we wouldn't have to waste bandwidth on disclaimers.
Unfortunately, the disclaimers are often necessary, as there are always a
few people who just *won't* behave properly.

And yeah, I wish he'd take his postings to alt.5yearold.babble, too; but
complain to *him*.  Getting him in trouble at work is absolutely inappro-
priate.

Terry R. Friedrichsen

terry@venus.sunquest.com  (Internet)
uunet!sunquest!terry      (Usenet)
terry@sds.sdsc.edu        (alternate address; I live in Tucson)
Newsgroups: sci.physics
From: dpc2@po.CWRU.Edu (David P. Caldwell)
Subject: Re: Blue Food (Re: Blue Sky)
Organization: Case Western Reserve University, Cleveland, Ohio, (USA)
Date: Thu, 30 Jul 92 19:59:28 GMT


About the blue food --

	My father told me then I was about 4 years old...

	"Don't eat blue food."
	
	He must have known about the jell-o.
-- 
David Caldwell (CALDWELL@CWBIO.BIOC.CWRU.EDU)
From: psyrobtw@ubvmsb.cc.buffalo.edu (Robert Weiss)
Newsgroups: sci.physics,sci.astro,sci.philosophy.tech,talk.religion.misc
Subject: Re: Structure of Time
Date: 29 Jul 92 03:18:00 GMT
Organization: University at Buffalo
News-Software: VAX/VMS VNEWS 1.41

In article <1992Jul28.102429.1@tnclus.tele.nokia.fi>, hporopudas@tnclus.tele.nokia.fi writes...

>   These "inquisitors" have contacted to my employer and they have tried
>to insult me and my paper. My employment is in danger at the moment.

	I'm sorry to see that. We expect a certain type of open 
discussion on a newsgroup. The biggest problem to reading something 
that is of no interest is either pressing the spacebar or the "n" key.
The fact that certain people contacted your employer to complain about 
a minor issue like this speaks more of their problem than anything 
else.

sincerely,
Robert Weiss
Newsgroups: sci.physics