HDTenEightyP/NetNews huggingface dataset:
From: bweiner@ruhets.rutgers.edu (Benjamin Weiner)
Newsgroups: sci.physics
Subject: Re: Length scales in physics
Date: 23 Aug 92 01:05:34 GMT
Organization: Rutgers Univ., New Brunswick, N.J.

responding to B. T. McInnes:

I think order-of-magnitude arguments are important especially for the
"when does this effect become important?" test, which really can save
a lot of time and wasted effort.  Of course a hand-waving derivation
of the Planck length doesn't _prove_ anything; however, anyone who
reads John's posts and thinks they really understand what's going on
is un-self-critical enough that they'll never really understand it no
matter how detailed the explanation.  On the other hand John's posts do
provide useful demystification for those who know they don't
understand it but maybe can be encouraged to believe that someday
they could understand.

The earlier question of, more-or-less, "why do physicists assume that
all constants are less than 10?" is very interesting, because most of
the time when you calculate something the constants that emerge are
relatively small.  Why?  I don't know, and I don't think it can be
fully explained by psychological reasons that determine our units or
what quantities we choose to calculate.  There's something there,
which explains why you just know, when Jackson says 
   show B = 96 pi NI/c (...)
that it will be a bitch and a half, because the constant is weird.
Newsgroups: sci.physics
From: hillp@ecf.toronto.edu (HILL Peter)
Subject: Re: BLACKHOLES IN THE CENTRE OF THE EARTH
Organization: University of Toronto, Engineering Computing Facility
Date: Wed, 19 Aug 1992 22:03:21 GMT

Responces from the Author;
 
Firstly I would like to thankyou for reading the article.
 
In reply to Warren Anderson:
I have independently come up with the idea.  I am unaware of anyone
previously reporting it.  I have searched extensively and found no
literature discussing the idea.  I have been trying to put bounds on the
mass, and field but have no real sense of what are realistic values.  I
think that to counteract the evaporation of the hole, may also be
accretion of mass from the host.  The Earth's magnetic field has remained
relatively constant.  The lava flows from the mid Alantic Rift have acted
as a kind of magnetic tape.  The poles have flipped more or less
chaotically.  Since realtime recording has begun the field has dropped
some 5% over the last 100 years but this is seen as a short term trend.
The conducting magma under the crust will act to damp and smooth any
short term trends.
 
There is a weak magnetic field in the Galaxy, that people have difficulty
explaining.  It too may be evidence of the field associtated with black
holes.  This time it may be one located with in the centre of our own
galaxy.  This may be easier to put limits on.
 
To Bob Cowles;
" Back of the envelope " is a quote from Steven Hawkings' book but I have
no direct reference for you.  There is the "event horizon" and this is a
kind of radius to consider and may relate to the collision cross section
with the matterial inside the Earth, Sun e.t.c.  Technically a blackhole
has infinite density.  I believe these holes are thought to be reminants
of the Big Bang rather than formed from compression of matter at a later
time.

Newsgroups: sci.physics,sci.astro
From: carl@aoa.aoa.utc.com (Carl Witthoft)
Subject: Re: Fossil Paradox (was: Structure of Time)
Organization: Adaptive Optics Associates
Date: Tue, 18 Aug 1992 12:01:08 GMT

In article <1992Aug17.105608.421@ecc.tased.edu.au> ecc_jim@ecc.tased.edu.au writes:
>There was a short story like this where a guy trod on a butterfly and totally
>changed everything. What was it called?
[about time travel and all that...]
I know the story but forget its name.  The premise was that time travellers
could shoot prehistoric animals.  The guide scoped out the area so
they only shot animals about to die anyway, and then pulled out the bullet 
and took off.  I distrusted then (1970 or so) and still distrust
the idea that killing a butterfly is bad but killing a Tyrannosaurus
3 seconds early, ripping its guts open, etc. is OK  (from a time-
travel causality point of view :=) )

-- 
Bobby Newmark, aka  Carl Witthoft @ Adaptive Optics Associates
aoa!carl@bbn.com  carl@aoa.utc.com
54 CambridgePark Drive, Cambridge,MA 02140 617-864-0201
**Just say NO to HMOs**
Newsgroups: sci.physics
From: marty@amaterasu.physics.uiuc.edu (Marty Gelfand)
Subject: Re: the nature of exclusion
Organization: Dept. of Physics, Univ. of Illinois at Urbana-Champaign
Date: Tue, 18 Aug 1992 15:14:18 GMT

>carl@aoa.aoa.utc.com (Carl Witthoft) writes...
>>An interesting continuation of this: if you pull enough energy
>>out of the right fermionic system and squish it enough, fermions
>>occasionally pair off to form boson-like units.  These units then
>>drop into a common energy state.  Cold He3 is one example, if I
>>remember correctly :=).
And David Ring asks...
>This one has always bugged the heck out of me. Say A1 and A2 pair up
>and B1 and B2 pair up. And each pair is in the same quantum state, then
>either A1 is in the same state as B1, or A1 is in the same state as B2.
>Both of which are forbidden. What's wrong?
>
  What's wrong is the picture that Carl has sketched.  In fact there are
some important differences between superfluid He3, or indeed 
superconductivity in electronic systems, and superfluidity in an ideal 
Bose gas.  There are even important differences between superfluidity in
He4 and in an ideal bose gas (which are particularly striking in the
vicinity of the phase transition).
  Superfluid He3 is actually too complicated for me to discuss (I really
don't know it well enough to write off the top of my head). Let me say
only that it is possible to have a superfluid ground state even with
purely repulsive interactions, so that that conventional notion of 
pairing is quite strained. Superfluidity in He3 is probably due 
primarily to this "Kohn-Luttinger" mechanism.
  Instead, let's look at a simpler matter: s-wave (which is to say,
conventional) superconductivity.  The Bardeen-Cooper-Schrieffer (BCS)
wavefunction is a good starting point for the description of
superconductivity in the weak-coupling limit.  It looks like
\prod_k (u_k + v_k a^\dagger_{k,up} a^\dagger_{-k,down}) | vacuum >
where the u's and v's are c-numbers, and a^\dagger's are creation operators.
This is manifestly antisymmetric.  One can say that the states
k,up and -k,down are "paired", since there are strong (complete!) 
correlations between the occupancies of those states. One can also that 
"all the pairs are in the same state" since they all have zero total
momentum.  But nonetheless the wavefunction is antisymmetric.  
  Perhaps the bottom line is that electrons don't pair, states do.
I hope someone will correct me if this is wrong...
--marty gelfand  
Newsgroups: sci.physics
From: white@disco-sol.dfki.uni-sb.de (Andrew P. White)
Newsgroups: sci.physics,sci.skeptic,alt.folklore.science
Subject: Re: The dangers in microwaved food...
Date: 20 Aug 92 14:03:05 GMT
	<8_#nrkg.payner@netcom.com>
Reply-To: white@dfki.uni-sb.de
Followup-To: sci.physics
Organization: DFKI Saarbruecken GmbH, D-W 6600 Saarbruecken
In-reply-to: payner@netcom.com's message of 20 Aug 92 02:59:27 GMT


How about : There ARE serious health risks.
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: SU(5) GUT (was Re: Superbashing ...)
Date: 16 Aug 92 19:28:09 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 <15AUG199200394835@zeus.tamu.edu>, dwr2560@zeus.tamu.edu (RING, DAVID WAYNE) writes...
> 
>SUSY SU(5) predicts the same process to take 10^34 years. But there are
>other decay modes which bring tau_p down to around 10^32. Also I think
>the 10^32 experimental limit is mode dependent. I know that extra higgses
>or generations ruin the proton lifetime, so it must be getting close.

This is an important, and often overlooked. point.  My "Blue Book" 
gives tau_p > 1,6 x 10^25 years.  Only for the specific mode looked for 
in the big proton-decay experiments, p -> e+ + pi-0, is the 
partial lifetime  measured to be > 5 x 10^32.  SU(5) GUT predicts this
particular mode to have a partial lifetime of 4.5 x 10^29+/-1.7 years.

For a good survey of everything experimentally known about proton decay,
check out the "Baryon Full Listings" in the Review of Particle Properties,
PRD _45_, No. 11, Part II, pp.VIII-1 - VIII-7.

SUPERKAMIOKANDE will start running in 1996, and push the limits on the 
crucial modes close to, if not beyond, the SUSY SU(5) prediction.

-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: scip1061@nuscc.nus.sg (Marc Paul Jozef)
Subject: Re: Hubble constant?
Organization: National University of Singapore
Date: Fri, 14 Aug 1992 12:35:40 GMT

  Dave, in your last response you write

"The perturbation is not small. In fact it changes the
 large scale geometry"

So you say. But Einstein doesn't agree with that. As I
understand it, we have no dispute over the following
points:

1. The global metric has a Friedmann shape.
2. Globally, the stress-energy tensor can be
   represented by a delta tensor.
3. Einstein's equation (which in this case
   reads: G(g) = d, i.e. G(g) = 0 nearly everywhere).

Now you try to convince me that G(g) is not equal to
zero. In other words, your global stress-energy tensor
T = G(g) is _nowhere_ zero, which violates 3.

In view of this, which of the above three points would
you care to drop?

Your toy model fails to convince me, for several reasons:

- As shown above, its 3-dimensional counterpart is not
  compatible with 1, 2, and 3, for G(g) = d (0) has no
  solutions with positive spatial curvature.
- You assumed at the outset that your toy universe
  expanded from a big bang and recontracted to a
  big crunch (the pumpkin), i.e. that it behaved like
  a `classical' solution with positive curvature.
  I missed the proof of that.
- You can unpaste whatever you want, but you can't
  make matter disappear. So your `unpasted' segments
  are still the worldlines of the point masses, and
  in particular not empty. 

By the way, how do you people copy other folks' text?

marc van loo
From: dbc@ecs.soton.ac.uk (Bryan Carpenter)
Newsgroups: sci.physics
Subject: Re: strong force
Date: 19 Aug 92 11:41:46 GMT

In <1992Aug18.175554.18835@pellns.alleg.edu> frisinv@alleg.edu (Vincent Frisina) writes:

>Is there a mathematical force law for the strong force? If so, what is it?
>If there is no exact formula, what's the closest we have from what's  
>known? Thanks.

     There's no simple formula like the Newtonian inverse
square law, or the electrostatic coulomb law.  You could
(I suppose) calculate such a law for the energy of two separated colour charges
for *classical* ``chromodynamics'', but it isn't very relevant because
quantum phenomena (especially colour confinement) change the picture
completely.

     From QCD-based lattice gauge theory computations, or phenomenological
potential models, you get potentials between very massive quark-antiquark
pairs that can be approximated by various formulae:

     V (r) = -a/r + br

isn't too bad, so far as I remember (br is the confining term; the
energy of the system grows linearly as you try to separate the two
quarks).

     So far as the forces between *hadrons* (eg protons) are concerned,
these are much more complicated.  There are lots of papers on
phenomenological proton-proton potentials, but the parametrisations that
emerge aren't particularly enlightening.  Of course, there's the
classical Yukawa potential

     V (r) = - a exp(-mr) / r

but it's very inaccurate except possibly at long distances (large r).

>-----
>Vince

Bryan
Newsgroups: sci.physics
From: jbaez@zermelo.mit.edu (John C. Baez)
Subject: Re: How to make big bucks using supersymmetry
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Fri, 14 Aug 92 20:59:03 GMT

In article <1992Aug14.024327.22167@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:
>I'll take on both of you. I bet that supersymmetry will be discovered in
>the same year in which category theory becomes popular among
>physicists.

Since this will probably occur shortly after hell freezes over, I would
not worry about having to pay off on such a bet anytime soon.
Newsgroups: sci.physics
From: sth@slipknot.mit.edu (Scott Hannahs)
Subject: Re: Faster than Light Comm. (ignoring the flames)
Keywords: Ignoring the previous flame war
Organization: Massachvsetts Institvte of Technology
Date: Fri, 14 Aug 1992 00:32:47 GMT

Just to do the bad no-no, to jump into a flame war in the middle, but
what the heck, statements like this need to be responded to.

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.

This is just a paraphase of the Capt. Kirk line: "I have seven science
labs on this ship, Bones.  I won't take no for an answer!"

This is great when you get to write the scripts and of course if works
out.  But the universe is what the universe is.  We can all believe in
our own realities which support FTL and all sorts of goodies but no one
has managed to actualy produce working experiments (devices, theories)
that violate the general perception that we call reality.  It would be
nice to explore the universe with FTL but unfortunately Special
Relativity works wonderfully well.  General Rel has smaller more subtle
effects and has not been as well tested.  FTL is acceptable in both of
these if one gives up causality.  If you can make things (ie FTL) true
because you desparately want them to be true causality is a little thing
that can be ignored.  As a physicist I must admit I prefer causality to
FTL.  So it goes.  My wishes (or belief that FTL "needs" to be done) are
irrelevant.  I think FTL is impossible.  The only way that it will be
proved is to wait for the end of the universe (I think it will be the
big crunch) and see if it happened.  Fortunately I didn't have to wait
that long to write my thesis.

Scott "Reality Check" Hannahs, F. Bitter Nationa Magnet Lab,
sth@slipknot.mit.edu
Newsgroups: sci.physics
From: scip1061@nuscc.nus.sg (Marc Paul Jozef)
Subject: Re: Hubble constant?
Organization: National University of Singapore
Date: Thu, 13 Aug 1992 04:51:48 GMT

  Dave, you indeed suggested a way of obtaining a
`Newtonian' slow-down, but one can give other ways
of evaluating the diverging integrals to give a
zero result, just as one can get any answer for
the sum of 1, -1/2, 1/3, - 1/4, 1/5 .... by a
suitable order of summing.
  Because you said something like `infinity minus
infinty might be everything' I thought you agreed
that your way of integrating is just one of the
arbitrary ways to get answers for diverging integrals.

Now, if one has an equation G(g) = d, where g is
a Friedmann-metric and d a `delta-tensor', then
G(g) = d is in effect a vacuum-equation G(g) = 0,
with the solutions I mentioned (see e.g. MTW).

Marc van loo.

Xref: sparky sci.physics:12762 alt.religion.kibology:3447
From: csquared@coos.dartmouth.edu (C Squared)
Newsgroups: sci.physics,alt.religion.kibology
Subject: Re: Kibocolliders (was: Re: Super Conducting Supercollider)
Date: 13 Aug 92 04:18:49 GMT
Distribution: na
Organization: Dartmouth College, Hanover, NH
Originator: csquared@coos.dartmouth.edu

In article <1992Aug13.030323.23331@nuscc.nus.sg> matmcinn@nuscc.nus.sg (Mcinnes B T (Dr)) writes:
>Scott: well, for heaven's sake,man, spill the beans! How did Kibo
>explain himself? For my part, I doubt that this person is really Kibo.
>How can you be sure that he is not an impostor?

You sci.physics people are a bunch of doubting Thomases
There is only one Kibo.  I think perhaps the .sig needs to be posted.

C Squared
From: sichase@csa2.lbl.gov (SCOTT I CHASE)
Newsgroups: sci.physics
Subject: Re: How to make big bucks using supersymmetry
Date: 20 Aug 92 03:09:20 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 <1992Aug14.164822.10838@utagraph.uta.edu>, sawyer@utahep.uta.edu (Lee Sawyer) writes...
> 
>    Since this thread has its antecedent in a post I made before the ICHEP 92,
>I might mentioned that the wager I made to a few friends is : Both CDF and
>D0 will report the mass of the gluino, based on high missing transverse energy
>events, before the next Rochester conference (July, 1994, in Glasgow).

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.

More seriously, does anyone know what the easiest SUSY particle to identify
experimentally is expected to be?  Given how elusive gluons are, I don't 
think that gluinos would be it.  I imagine that photinos or sleptons are more
likely.

-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: sal7@ellis.uchicago.edu (Rob Salgado)
Subject: Order-of-Magnitude problems
Reply-To: sal7@midway.uchicago.edu
Organization: University of Chicago Computing Organizations
Date: Sat, 15 Aug 1992 10:57:35 GMT

        In trying to improve my physical intuition, I've been doing lots
of Order-Of-Magnitude (Back-Of-The-Envelope) problems.  
...but I'm stumped by the following:
 
        Use the uncertainty principle to compute how long an ordinary
        lead pencil can be balanced upside down on its point.
                                                [QM: Das/Melissinos p. 53]
Any ideas?
 
 
        ...And while I'm on the subject, there's a nice collection of
OOM problems in a [discontinued] column: "The Back of the Envelope" edited
by Edward Purcell in Am.J.Phys. beginning in vol 51(1), Jan 1983, p11.
 
Does anyone know of any other interesting OOM problems/solutions?
-- 
Rob Salgado
sal7@ellis.uchicago.edu

Newsgroups: sci.physics,sci.math
From: phillies@wpi.WPI.EDU (George D. Phillies)
Subject: 'SSC and biochemistry?
Organization: Worcester Polytechnic Institute
Date: Wed, 12 Aug 1992 15:48:13 GMT

In  <85904@netnews.upenn.edu> weemba@sagi.wistar.upenn.edu (Matthew P 
Wiener) continued a discussion with crb7q@kelvin.seas.Virginia.EDU 
(Cameron Randale Bass) on the ability of SSC to reveal information
of relevance to biology.  An *apparent* topic of discussion is the
possibility that electroweak or nuclear interactions are responsible 
for the dominance of compounds of one chirality (per class of 
compound, not necessarily the same for all classes) in biological 
systems.  

This problem has been investigated by direct experimental means, such 
as studies to determine if amino acid degradation associated with 
radioactive decay has a handedness preference.  To the best of my 
knowledge, no convincing positive results have been obtained.

[exceedingly long discussion deleted]

Suppose one had a demonstration that the preference in nature for l- 
over d-amino acids is based on a natural tendency in the prebiotic 
world for the d-amino acids to be destroyed.  This demonstration is 
of almost no importance to biochemical research, except for the very 
small community that is actually working on chemical evolution.  Oh, 
the citation level of such a discovery, especially if weighted by the 
number of copies produced of each citing source, will be enormous, 
since the result will be reproduced in every high school and junior 
high school biology text in the United States.  The people who make 
the discovery will likely be able to publish it in Nature, and may 
well be able to take home a Nobel Prize.  A Nobel Prize they would not 
deserve, because the impact of such a discovery on the remainder of 
biochemical science would be practically non-existent.

One could argue that the interest of physicists in the origin of 
biochirality is symptomatic of the oft-heard biologist's critique of 
biophysics, once given to me as "chasing butterflies with antiaircraft 
cannon" --- brilliant instrumentation, feeble choice of topics.
(All biophysics is NOT like this.  For a first rate effort to apply 
real physics to important biology, consider Noolandi's application of 
the reptation model of polymer dynamics to gel electrophoresis.)

If you want to benefit biology and chemistry with superconducting 
magnets and supercomputers, chop the SSC into short pieces (on magnet 
each), rearrange the field configuration and rf sources a bit, and 
present one thousand of the country's "leading" chemistry, biology, 
and biochemistry departments (this is getting way down the list) with 
two or three high-field (say, 600MHz) NMR units, per department. (And 
leave a few units for the petroleum geologists and paleontologists.) 
The effect on synthetic organic chemistry, protein structure studies, 
etc.  You would have the same effect on jobs, and a far larger impact 
on modern science.  

If you want to justify SSC, it must be done on the basis of the 
alleged importance of HEP, not on the basis of spinoffs to other 
fields.

George Phillies
phillies@wpi.wpi.edu
Newsgroups: sci.physics
From: m14494@mwvm.mitre.org (Mike White)
Subject: Info on Biefield-Brown Effect needed
Organization: The MITRE Corporation
Distribution: na
Date: Fri, 21 Aug 1992 12:18:01 GMT

I'm looking for information and/or references on the
Biefield-Brown effect (something to do with charged
particles or objects).  Any help will be greatly 
appreciated.  Post here, or email to

m14494@mwvm.mitre.org

Thanks.

************************
* These are my opinions only.*
************************
Newsgroups: sci.physics