HDTenEightyP/NetNews huggingface dataset:
From: heinzl@hpw2 (Heinz Lottermoser)
Newsgroups: sci.physics,alt.sex
Subject: Re: Subject?
Date: 1 Sep 92 00:33:49 GMT
Distribution: na
X-Newsreader: Tin 1.1 PL4

Do any of you even know what "terminal velocity" is???  The higher you are
does NOT mean the faster you fall unless you are in a friction free 
environment, or the coef. of friction is so low that it does not overcome
the acceleration.  

Sorry, just can't stand bad physics...

The Howler...
Newsgroups: sci.physics
From: matmcinn@nuscc.nus.sg (Mcinnes B T (Dr))
Subject: Re: E=mc2?
Organization: National University of Singapore
Date: Tue, 1 Sep 1992 04:10:46 GMT

dwr2560@zeus.tamu.edu (RING, DAVID WAYNE) writes:
: gross@maxwell.ucsc.edu (Mike Gross) writes...
: >But nuclear weapons _do_ turn matter into energy. For a fusion bomb, the key
: >point is that a deuterium and a tritium nucleus weigh less than a helium 
: >nucleus and a neutron. A gamma ray is also among the fusion products. Thus,
: >you have matter + ~10 MeV -> less matter + a lot more energy (grossly
: >simplified, of course). This _is_ a conversion from matter to energy. 
: 
: Springs do the same thing. A compressed spring has kx^2/2c^2 more mass than
: a relaxed one. So releasing a spring turns mass into energy.
: 
: Dave Ring
That's right. So to say that nuclear weapons are connected with E=mc^2
makes about as much sense as saying that your bedsprings are nuclear
powered. In all these instances, all we have is energy  being converted
to other forms of energy. Of course I am neglecting
particle-antiparticle things, but I am told that in fission bombs most
of the energy comes from releasing nuclear binding ENERGY. Correct me if
I am wrong about this.
: dwr2560@zeus.tamu.edu
From: phys169@csc.canterbury.ac.nz
Newsgroups: sci.physics
Subject: Re: My son would like to know about photons...
Date: 27 Aug 92 10:37:41 +1200
Organization: University of Canterbury, Christchurch, New Zealand

My son asked...
> If you can split atoms, can you split photons?

I got quite a lot of replies to this, ranging from "yes" to "no", with lots in
the middle.  Although I work in a physics department (okay, as a programmer), I
found it very hard to answer some of my son's questions properly (and of course
this was the main one), since there are all sorts of things that people
normally know by the time they get to thinking about such things.  I don't like
to answer simply "yes" or "no" - apart from the fact that such answers are
inappropriate here anyway. But I guess if I had stuck to simple yes/no answers
a few questions back, he wouldn't have got me onto difficult ones. :-)

For what it is worth, I used a mixture of the explanations and let him read the
replies & posting, and this is what seems to have been the most understandable
way of putting it... (remember he's 9 years old)...

 You can break up an atom (or nucleus - I had to explain that one) by hitting
 it with something, like an automobile getting hit and you end up with an
 engine here and a headlamp there.

 Photons aren't like an atom (which is made up of obvious "bits"), it is
 basically energy, so you can't break it up. You can, however, get two
 half-power photons out of one.  You could almost call that splitting, but
 photons are more like bank accounts, where you can divide up the money into
 two accounts (the same notes and coins wouldn't necessarily come out of the
 accounts that went in, but it is the same total value still).

The difficult part was definately explaining high-energy photons producing an
electron/positron pair.  The problem I'm left with is this: if you fire a
photon at an atom, you get an electron and protons and stuff (I got a bit
bogged down explaining ions and neutons and such like so I skipped it). Fine.
But if that gamma photon happens to hit another photon, and you get e+ and e-,
why can't you also say these were constituent bits of the photon, like we said
with an atom? I extended the bank-account analogy there, suggesting an account
for positrons and electrons, but that was stretching things a bit far.

Thanks especially for the mention of some suitable books.  A lot aren't really
geared to younger readers interested in fundamental particles that have their
own theories about black holes and the universe, and questions whether photons
go exactly at the speed of light!

Mark Aitchison.
From: nicho@VNET.IBM.COM
Newsgroups: sci.physics
Subject: Re: Impure Mathematics
Date: 1 Sep 92 10:26:06 GMT
Reply-To: nicho@vnet.ibm.com

In <1992Aug27.182603.28922@newshost.lanl.gov> Jim Giles writes:
>(except to point out that it's about as old as the century and may
>have interest as a cultural artefact of a previous generation's
>disregard for PC attitudes).

 Lets not omit members of the current generation who regard the American
preoccupation with 'PC' attitudes as a wonderfully zany piece of
navel gazing.
 -----------------------------------------------------------------
               ** Of course I don't speak for IBM **
Greg Nicholls ... nicho@vnet.ibm.com or nicho@cix.compulink.co.uk
                  voice/fax: 44-794-516038
From: mppu3@syma.sussex.ac.uk (Conor McMenamin)
Newsgroups: sci.physics
Subject: Re: Faster than Light Comm.
Date: 14 Aug 92 19:35:15 GMT
Organization: University of Sussex

snarfy@cruzio.santa-cruz.ca.us writes:
: 
:     The  serious  responses  indeed  prompt me to open a book and learn more
:    physics, or  get  help  from  third  parties.   Still  ,  none  of  these
:    objections   have  yet  convinced  me  to  adopt  a  belief  system  that
:    continually strives to rule out the possibility of FTL communications. To
:    the contrary , the more I learn about nature , the more I'm  inclined  to
:    think  positively  . I don't think that anything that needs to be done as
:    much as breaking the light barrier needs to be done, for the sake of  the
:    survival of the human species, can really be impossible.

Dear Snarfy,
            I don't want to get drawn into this flame war, but I do
feel moved to reply to your statements above. You seem to be approaching
the whole topic here as some kind of religious analogue, talking about
'belief system's and the power of positive thinking. If you want to
discuss science with scientists, then you must approach it from a
scientific standpoint, or you will always meet with stiff resistance.
Modern science is based on scepticism, not belief systems and the like.
If I believe hard enough, does it make the moon a swiss cheese?

	Many of the people who are mailing and posting in reply to you
are physicists, which I very much doubt you are. They will not accept
what you say because there is a very successful theory backed with a
huge number of physical measurements which all seem to show that your
belief is incorrect, and that FTL is intrinsically impossible. Until you
show some sign of accurate physical measurements which refute the theory
of relativity, you will never convince any of these people that you are
correct. However you will convince many of them that you are some
ignoramus who has read too many science fiction books and believes that
human beings are all-conquering super beings rather than the rather
insignificant species which, on a universal scale, we undoubtedly are.
Would it be useful to make energy out of nothing? Perhaps more useful
than FTL? And if so, isn't it inevitable that this will one day be
possible, because we humans wish it to be so?

	When you understand a small fraction of the physics you wish you
did, then perhaps you will abandon belief systems and 'religious' science,
and become a poster that physicists can bear to read. Until then expect
more of the same.

Conor.

P.S. I have an interesting paper by Fleishmann and Pons you may like to
read, now this _would_ be useful....
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Report on Philosophies of Physicists
Date: 3 Sep 92 22:32:19 GMT
Article-I.D.: husc8.mcirvin.715559539

johan@blade.stack.urc.tue.nl (Johan Wevers) writes:

>Some people invented quantum logic: a 3 valued logic. But I think this
>is also not good enough: if the electron would have a probability of
>90% of going through one slit, and 10% of going through the other, I
>think a 3-valued logic, which answers the truth walue of the question
>`did the electron pass slit 1' with 1/2, is not good. I would suggest
>to introduce a continue logic, where this truth values would be
>0.9 and 0.1. The boolean logic is a limit case in which only the values
>1 and 0 can occur.

Of course, to get in all the information you'd have to introduce
truth values with complex phases as well as continuous magnitudes.

Has anybody here worked with quantum logic?  Does it just include
an extra truth value to eliminate the excluded middle, or is there
some attempt to turn the mathematics of Hilbert spaces into 
a system of logic assigning, say, phases and magnitudes to
various propositions?  People ask me this every so often, and I
don't know anything about it.

-- 
Matt McIrvin, Cambridge, Massachusetts, USA 
Xref: sparky sci.physics:14046 sci.math:10944
From: baez@ucrmath.ucr.edu (john baez)
Newsgroups: sci.physics,sci.math
Subject: Re: Symmetries, groups, and categories
Date: 28 Aug 92 18:34:30 GMT
Article-I.D.: galaxy.22034
Followup-To: sci.physics
Distribution: na
Organization: University of California, Riverside

In article <1992Aug25.045603.13611@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:
>I think the opposite. Physicists tend to pay too much attetion to
>representation theory and not enough to the underlying groups.

You are just being difficult, as usual.  :-)  The fact that physicists
may overemphasize representations is not in contradiction with the fact
that any decent introduction to group theory should discuss
representations.

>For one
>thing, it encourages them to forget the fact that Lie groups are not
>always connected. 

This is a common slip-up but I think the problem is that physicists are
more comfortable with Lie algebra reps than group reps.  The Lie
algebra, of course, doesn't know everything about the Lie group's
topology: it forgets about non-simple-connectedness and
non-connectedness.  Both these are things it's taken physicists a while
to get used to.  

>Remember how the string theorists used to talk about
>"embedding the spin connection in the gauge group"?

Nope.  I don't talk to string theorists a whole lot.

>Also: in what way is the holonomy group of a Riemannian manifold to be
>interpreted as a group of "symmetries"?

I have no idea!  Perhaps you mean the isotropy group?  That is of course
the group of symmetries of the Riemannian manifold; that's what I meant
to say once upon a time.

One should of course keep straight the difference between the group of
symmetries of the physical theory, that is, the phase space (if it's a
classical theory), and the group of symmetries of any particular
SOLUTION of the theory.  The isometry group of a Riemannian manifold
pays the latter role in GR.
Newsgroups: sci.physics
Subject: Re: Refs on Japaneese spinning weight experiment?
From: hoyt@isus.UUCP (Hoyt A. Stearns jr.)
Date: 24 Aug 92 13:22:57 GMT
Organization: International Society of Unified Science

In article <23AUG199214582737@erin.caltech.edu> shoppa@erin.caltech.edu (TIM SHOPPA) writes:
>Hi!
>	A few years ago (2-4?) the results of a Japaneese experiment that
>spun disks in different directions and found different masses was published.
>article?
>

It's in Physical Review Letters, Vol. 63 Number 25, 18 December 1989:

	"Anomalous Weight Reduction on a Gyroscope's Right Rotations around the
	Vertical Axis on the Earth"
			-Hideo Hayasaka and Sakae Takeuchi

-- 
Hoyt A. Stearns jr.|hoyt@          | International Society of Unified Science|
4131 E. Cannon Dr. |isus.tnet.com  | Advancing Dewey B. Larson's Reciprocal  |
Phoenix, AZ. 85028 |ncar!enuucp!   | System- a unified physical theory.      |
voice_602_996_1717 telesys!isus!hoyt The Universe in two postulates!_________|
From: gross@maxwell.ucsc.edu (Mike Gross)
Newsgroups: sci.physics
Subject: Re: My son would like to know about photons...
Date: 26 Aug 92 07:31:12 GMT
Organization: University of California, Santa Cruz
NNTP-Posting-Host: maxwell.ucsc.edu

In <1992Aug26.142916.533@csc.canterbury.ac.nz> phys169@csc.canterbury.ac.nz writes:

>I have a question on behalf of my 9-year old son...

>If you can split atoms, can you split photons?

In one sense, yes. If your photon is energetic enough, and there is something
around nearby to absorb momentum, you can split your photon into an
electron and positron (for example). How energetic does it have to be?
The absolute minimum requires a gamma ray, although the energy is not too
outlandish. But you do have to have enough energy to create two particles
(use E=mc**2 on the electrons here). 

Please note that this is _not_ saying that the photon is made up of smaller
pieces. As far as anyone knows, the photon is a truly elementary particle.
This is a reflection of the rather odd definition of the "vacuum" that the
elementary particle physicists use.

Best wishes!

Mike Gross
Physics Board
Univ of California                GO SLUGS!!!!!
Santa Cruz, CA 95064
gross@maxwell.ucsc.edu
Newsgroups: sci.physics
From: terry@aslws01.asl.dl.nec.com (Terry Bollinger)
Subject: third try
Organization: NEC America, Inc. Irving, Texas
Date: Tue, 1 Sep 1992 04:17:10 GMT

Ah well... I'll give it one more try:

    In a large-scale system you can track conservation of angular momentum
    can be tracked by attaching angular momentum vectors to the component
    objects of that system.  The sum of all such vectors will be invariant
    over time as long as the system is not disturbed from outside, and the
    magnitude and orientation of such vectors are independent of observers.

    In an extremely small system you can still track conservation of angular
    momentum by attaching vectors to the objects, but the vectors will now
    be quantized (multiples of 1/2 hbar) and, more importantly, the exact
    orientation of these vectors will depend on HOW they are measured.
    Such a dependence unavoidably leads to the implication that the angular
    mometum vector sum for the system will no longer invariant over time.
    It can (and will) change from one set of measurements to the next.

    Finally, I'll assert without bothering to try and prove it here that
    there is no *fundamental* reason why the no-longer-invariant vector sum
    I've just described could not in some cases become arbitrarily large.

    If you accept the above premises, my question is this:  What is the
    physical meaning, if any, of the arbitrarily large vectors that could
    in principle arise as a result of making many observations of quantum
    spins within a single system?

Can anyone answer this one for me, or not?

				Cheers & maybe a few Grumps,
				Terry Bollinger

Newsgroups: sci.physics
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: ELECTRON HELIX : ITS POWER AND POSSIBLITIES
Organization: University of Virginia
Date: Wed, 2 Sep 1992 13:55:58 GMT

In article <12950073@hpspdla.spd.HP.COM> ric@hpspdla.spd.HP.COM (Ric Peregrino) writes:
>
>Regarding the electron helix.
>
>This won't work.
>
>You can't make a helix with magnetic fields which produces a bigger 
>magnetic field than the sources. 
>
>You can't accelerate with a magnetic field; F = Q V x B.

     "Particles within a stochastic - or chaotic - web in 
     phase space can be accelerated to high energies even by
     weak magnetic fields."  A.A. Chernikov /etal, Nature 326:559 (1987).

                              dale bass



-- 
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926
From: clark@bork.phy (Charles Clark)
Newsgroups: sci.physics
Subject: Re: quantization of angular momentum
Date: 2 Sep 92 23:25:17 GMT
Distribution: na

In article <25947@dog.ee.lbl.gov> sichase@csa3.lbl.gov (SCOTT I CHASE)  
writes:
> In article <1992Sep1.203830.2793@galois.mit.edu>, jbaez@riesz.mit.edu  
(John C. Baez) writes...
> >In article <25903@dog.ee.lbl.gov> sichase@csa2.lbl.gov writes:
> >>L is not quantized under all circumstances.  For a free particle, 
> >>none of r,p, and L are quantized.  
> > 
> >Ouch!  L is quantized under all circumstances.  Its eigenvalues are
> >half-integer multiples of hbar, even for free particles.
>
 
1)

> Am I off base here?  

2)

>If you have a free scalar particle with wave function
> exp(-iEt+px), how is L quantized?
> 
> -Scott

1) Yes.

2) It is a superposition of eigenstates of L.  It's easy to
   construct a free particle state that is also an eigenfunction of L.
   BTW one can also have bound states even in spherically symmetric
   potentials (e.g. 3-d H.O., hydrogen atom) that are not 
   eigenfunctions of L.
From: hall@vice.ICO.TEK.COM (Hal F Lillywhite)
Newsgroups: sci.physics
Subject: Re: BAROMETERS (was Re: Subject?)
Date: 3 Sep 92 13:53:42 GMT
Organization: Tektronix Inc., Beaverton, Or.

In article <ZOWIE.92Sep2094047@daedalus.stanford.edu> zowie@daedalus.stanford.edu (Craig "Powderkeg" DeForest) writes:

>If everyone knew more about economics, they might be less inclined to believe
>every liar who comes along claiming to be able to balance the federal budget,
>increase spending, *and* not raise taxes...

What a dreamer you are!  Unfortunately a little wishful thinking can
overwhelm a lot of knowledge.
From: snarfy@cruzio.santa-cruz.ca.us
Newsgroups: sci.physics
Subject: Electron Helix
Keywords: Electron Helix High Amp Experiments
Date: Thu, 03 Sep 92 09:29:37 PDT
Reply-To: snarfy@cruzio.santa-cruz.ca.us



    Interesting article.  I  found  it  difficult  to  conform  to  my  word
   processor  though  due  to the wide format. I hope you  don't allow  Bass
   ( >we call them "generators") to discourage you. He's prone to  obnoxious
   comments  usually  totally irrelevant to the point .  As far as practical
   experiments are concerned, you may  want  to  contact  Frank  Stenger  (a
   retired  NASA  research engineer who has been working along the lines you
   suggest). He thinks that the phenomena known as  "ball  lightning"  is  a
   result  of  electron  -  positron  pair  formation which can occur at the
   ampere levels you mention. He has a  large  capacitor  bank  utilizing  a
   triggered  spark gap .  I think he uses a Z axis pinch chamber which I've
   noticed in relevant published research papers.

   Ball  Lighting  is  a  documented  phenomena  still  unexplained  by  the
   netclowns around here (who think they know everything).

   Stenger ,on the other hand , is a serious researcher who builds his own
   equipment .

   His address is:

   4562 Fox Road
   Kingsville ,Ohio 44048
From: mcfarlan@corona.math.washington.edu (Thomas J. McFarlane)
Newsgroups: sci.physics
Subject: Re: E=mc2?
Date: 4 Sep 92 20:55:40 GMT
Article-I.D.: u.1992Sep4.205540.26583
Organization: University of Washington, Mathematics, Seattle

In article <10585@sun13.scri.fsu.edu> jac@ds8.scri.fsu.edu (Jim Carr) writes:

>Thus relativistic mechanics is not at the foundation of the physics 
>of the bomb.  Indeed, from the perspective of 1943, quantum mechanics 
>was hardly required since the models used to make sense of the data 
>concerning uranium fission were macroscopic ones and not true quantum 
>mechanical calculations.  
>
  It's a little hard for me to swallow that QM was hardly needed.
Was this really the case? 

Tom McFarlane
From: Eric_S_Klien@cup.portal.com
Newsgroups: sci.physics
Subject: E=MC^2
Date: Mon, 31 Aug 92 03:34:59 PDT
Organization: The Portal System (TM)
Distribution: world

What is one gram of matter equal to in energy?  In other words, how 
do you figure out E = MC^2?
 
                                                         Eric Klien
From: cyberman@toz.buffalo.ny.us (Cyberman)
Newsgroups: sci.physics
Subject: Local Bus Specs
Date: 4 Sep 92 01:28:39 GMT
X-Maildoor: WaflineMail 1.00r

Does Anyone know where I can procure documentation on Local Bus?
As in specification etc?  Or is thier still no standard?

        Stephen Cyberman@Toz.Buffalo.NY.US
        Scripted at Wed  09-02-1992  00:33:44

... WARNING!  Removal of this tagline prohibited by law!
--- Blue Wave/QWK v2.10
                                                                                          
Newsgroups: sci.physics
From: gapdrr@gsusgi2.gsu.edu (Daniel R T Rothman)
Subject: Re: Rotating Bucket of Water in a Gravitation Field
Organization: Georgia State University
Date: Wed, 2 Sep 1992 18:16:32 GMT

voros@physics.monash.edu.au (Joe Voros) writes:

>wdb3926@zeus.tamu.edu (BRUTON, WILLIAM DANIEL) writes:
>> Anyone ever proved that the surface of water in a bucket rotating
>> in a gravitational field is a paraboloid? 

>Many moons ago, yes.  Also, that if the bottom of the paraboloid just
>touches the bottom of the bucket, that the amount of water left in the
>bucket is exactly half, if it was full to begin with.

I believe this is true if you tip the bucket, but under rotation the
questions of mass, inertia, and above all surface tension (a nasty, variable
thing, that) conspire to give the parabaloid different curvatures. This
experiment probably looks a LOT different if you do it with mercury or
ethyl alcohol.

daniel rothman
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: Impure Mathematics
Date: 28 Aug 92 19:34:36 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 <Aug.28.13.28.14.1992.13802@ruhets.rutgers.edu>, bweiner@ruhets.rutgers.edu (Benjamin Weiner) writes...
> 
>What I wanted to say is, does Suzanne really need to make a well-
>reasoned argument that jokes about rape aren't funny?  Just sit back

Of course not.  But she does need to make a case for why unfunny jokes
about rape should never be posted to USENET and why the original poster
should indeed feel like a neanderthal.

-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: sci20035@nusunix3.nus.sg (LIM WOOI BENG)
Newsgroups: sci.physics
Subject: De Broglie wavelength and frequency
Date: 24 Aug 92 03:14:57 GMT
Organization: National University of Singapore


						*The Edge*
From: sichase@csa3.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: What's new with chaotic dynamics?
Date: 26 Aug 92 01:12:19 GMT
Reply-To: sichase@csa3.lbl.gov
Distribution: na
Organization: Lawrence Berkeley Laboratory - Berkeley, CA, USA
NNTP-Posting-Host: 128.3.254.198
News-Software: VAX/VMS VNEWS 1.3-4

In article <l9l9fdINNrf6@news.bbn.com>, hagstrop@oberon.mathcs.carleton.edu (Paul Hagstrom) writes...
>I realize that this is an incredibly unfair question to ask, but I will pose it  
>anyway, just to see what the response is..
> 

I suggest "controlling chaos" is a good paper topic.  It is new and trendy,
and there are good introductory papers in Science, Nature, etc. that you
could dig up.

-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