HDTenEightyP/NetNews huggingface dataset:
From: pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt)
Subject: Re: Electrons in the body
Organization: Computer Science Department,  Stanford University.
Date: Thu, 10 Sep 1992 05:24:50 GMT

In article <1992Sep10.014518.15092@nntpd.lkg.dec.com> moroney@ramblr.enet.dec.com writes:
>In article <79438@ut-emx.uucp>, ofman@zonker.ph.utexas.edu (Leon Ofman) writes...
>>In article <00960110.2D669340@Msu.oscs.montana.edu> uchpcjv@Msu.oscs.montana.edu writes:
>>>>>Could anyone give me a rough estimate of the percent of mass of a human
>>>>>body which is made of electrons? 
>
>>>  ROUGH ESTIMATE:  about 1/2000 of body mass.  Rought estimate.
>
>>Rough estimate: 1/1000 (don't forget the neutrons!)
>
>That would make it about 1/4000 or so.

Don't forget hydrogen (no neutrons).  This and tightening up the 2000
number to 1840 yields 1/3350, which should be within a percent or so of
the truth.

(Hydrogen makes a 10% difference for water, which is 72% of us, and
about a 7% difference for the remaining 28%.  The typical vertebrate
organic molecule is mostly H,C,O,N with roughly as many H's as the
combined number of C,O,N's.)

-- 
======================================================| God found the positive
Vaughan Pratt   pratt@cs.Stanford.EDU   415-494-2545  | integers, zero was
======================================================| there when He arrived.
Newsgroups: sci.physics
From: frank@rover.uchicago.edu (Frank - Hardware Hacker - Borger)
Subject: Re: Question about falling elevator...
News-Software: VAX/VMS VNEWS 1.41    
Reply-To: frank@rover.uchicago.edu
Organization: Joint Center for Radiation Therapy
Date: Sat, 12 Sep 1992 14:27:00 GMT

In article <1992Sep11.212549.645@CSD-NewsHost.Stanford.EDU>, pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes...
>In article <88580@netnews.upenn.edu> owens@hilbert.wharton.upenn.edu (Susan Owens) writes:
>>
>>  I have a question that I thought maybe someone here could answer.  It
>>concerns a falling elevator.  If I was in an elevator that was falling
>>say 20 stories what would happen if I jumped right before I hit the
>>ground.
> 
>Your best bet is to press your head firmly against the floor.  Here's
>why.
>...
>This leaves the question of how to press your head against the floor
>while in free fall.  With luck the fall won't be completely free.

	Actually, elevator mechanisms have braking mechanisms that do just
	this, limit falling speed, independant of any cable, etc.

	So, in the event that the very unlikely does occur, and you end up
	in an elevator dropping at HIGH SPEED, but not in FREE FALL, the
	best thing to do would be to lay down flat on your back.

   Frank R. Borger - Physicist    __       Internet:  Frank@rover.uchicago.edu
Michael Reese - Univ. of Chicago |___      Phone : 312-791-8075 fax : 567-7455
  Center for Radiation Therapy   | |_) _   A man in love is incomplete until
                                   | \|_)  he is married. Then he is finished.
    "Birthplace of Softball"          |_)  Zsa Zsa Gabor
From: carlip@landau.ucdavis.edu (Steve Carlip)
Newsgroups: sci.physics
Subject: Re: Did electric/magnetic symmetry "break"?
Date: 8 Sep 92 20:52:31 GMT
Organization: Physics, UC Davis

In article <1992Sep8.012930.25239@galois.mit.edu> jbaez@riesz.mit.edu (John C. Baez) writes:
>
>Afficionados of those who plunged in where angels feared to tread will
>have to check out Eddington's book in which he tried to "deduce" that
>the fine structure constant was exactly 136.  Then it turned out to be
>137 and he realized he'd left one something-or-other out.  Well, then
>it turned out not to be exactly 137 either. [...] 
>
Hans Bethe and two others (G. Beck and W. Riezler) then wrote a very
funny paper in which they "derived" the fact that absolute zero was
-273 degrees (centigrade, of course) with the same kind of numerology.
(After all, -273 = -2x137 +1.)  The paper was accepted by Die
Naturwissenschaften, apparently without the editor realizing it was
a spoof, and appeared in 1931.  It's reprinted in the book _A Random
Walk in Science_, which I strongly recommend (collection compiled by
R.L. Weber, published by The Institute of Physics, London,
ISBN 0 85498 027 x).

Steve Carlip
carlip@dirac.ucdavis.edu
Newsgroups: sci.physics,sci.math
From: jbaez@riesz.mit.edu (John C. Baez)
Subject: Re: Report on Philosophies of Physicists
Organization: MIT Department of Mathematics, Cambridge, MA
Date: Thu, 10 Sep 92 17:32:25 GMT

In article <1992Sep10.034627.3965@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.Stanford.EDU (Vaughan R. Pratt) writes:
>Mathematics is smooth?  I'll have whatever you're smoking.  Whose
>mathematics?  If ZFC, that's an r.e.-complete theory and hence not just
>fuzzy but chaotic.  If first order number theory, that's the whole
>arithmetic hierarchy and hence wildly chaotic.  If second order
>logic...you get the drift.  The only smooth mathematics is polynomial
>time algorithms, and even there you have to break out the dramamine at
>around n^5.

Well, I don't go through all well-formed formulae and check one by one
to see if they're theorems.  I follow the veins.  :-)
From: jbaez@riesz.mit.edu (John C. Baez)
Newsgroups: sci.physics
Subject: Re: Wave/particle duality
Keywords: photon,particle,dual slits,interference,quantum waves
Date: 14 Sep 92 23:50:46 GMT
Organization: MIT Department of Mathematics, Cambridge, MA

danforth@riacs.edu (Douglas G. Danforth) asks:

>Are the photons point-like or is it our eyes that have point-like regions
>of activation?

This is a trick question.  :-)  The whole point about quantum
mechanics is that asking whether photons are "really" pointlike or
wavelike is gonna get you in trouble.  Better to ask, if I do
experiment X, what will the results be?  

In any event, our eyes have lots of quite small regions of activation,
namely molecules of some sort that respond to light (the word
"rhodopsin" comes to mind but I really don't know), and so they only
fire "if the photon is there".   Thus they measure the position
information of a photon fairly accurately - but still the frequency
information to some degree (which is why we see colors).  A different
sort of detection system could improve the measurement of position
information at the expense of accuracy of the measurement of
frequency, or vice versa.  

On a different note, regarding my suggestion that there was a
mathematically precise definition of random sequences, due to Chaitin,
I was told via email that the definition of algorithmic randomness is
due to Kolmogorov and can be found in:

A.N. Kolmogorov. Three Approaches to the Concept of the Amount
of Information. {\em Probl. Inf. Transm.}, 1(1), 1965.

A good exposition of later developments is supposed to be:

\bibitem{ku87} A.N.Kolmogorov, V.A.Uspenskii. Algorithms and Randomness.
 {\em Theoria Veroyatnostey i ee Primeneniya = Theory of Probability and its
Applications}, 3/32:389-412, 1987.

I will let others fight any priority disputes; I am an innocent
bystander!  

I should add that this definition does not do allow you to use a
Turing machine to decide whether a given sequence is random or not.  
(We've been through this all before, actually, but newcomers might be
interested.)  



.
From: paul@mtnmath.UUCP (Paul Budnik)
Newsgroups: sci.physics
Subject: Re: Hidden variable theories, was: Uncertainty Princi
Date: 10 Sep 92 16:10:54 GMT
Organization: Mountain Math Software, P. O. Box 2124, Saratoga. CA 95070

In article <1992Sep9.185040.18757@riacs.edu>, danforth@riacs.edu (Douglas G. Danforth) writes:

> This assumes that Bell's theorem is a definitive and final answer.  For
> inefficient detectors it is quite easy to construct a model which gives
> the EXACT quantum mechanical two-particle correlations.  Bell's theorem
> does not address this case of inefficient detectors.

You need to distinguish between Bell's result and the experimental tests
of it. Bell's theorem implies that quantum mechanics is not a local theory
and suggests that this should be experimentally detectable. Bell's theorem
does not address and is not affected by the many practical problems in
conducting an experiment.

> In summary, at this time, one can NOT make the claim that "Any theory of any
> form that is consistent with quantum mechanics must also be nonlocal".

Quantum mechanics *is* a nonlocal *theory*. This is a strictly mathematical
derivation that has nothing to do with experimental results.
Of course I think quantum mechanics is both not local and not correct.
I believe this will ultimately be confirmed experimentally.

One problem with testing Bell's inequality is that *no* experiment
can ever be absolutely conclusive. Two loopholes that can always exist are:

	1. The information is transmitted at superluminal but still finite speed
	   and thus locality is preserved.

	2. The results of both experiments including human manipulation
	   of a polarizer was predetermined and thus the correlations can
	   be produced with out nonlocal effects.

Any real experiment will always have some additional loopholes. Aspect
was certainly aware that detector efficiency was an issue. I do not
completely follow your argument about efficiency. If you are saying that
only those detections that confirmed violations of Bell's inequality were
detected because of some unknown physical process, I agree that this is 
possible. I am sure the experimenters were aware of this and classified
it is another improbable but still possible loophole. 

Paul Budnik
Newsgroups: sci.physics,sci.math
From: torkel@sics.se (Torkel Franzen)
Subject: Re: Report on Philosophies of Physicists
Organization: Swedish Institute of Computer Science, Kista
	<1992Sep14.005448.28555@CSD-NewsHost.Stanford.EDU>
	<TORKEL.92Sep14074902@bast.sics.se>
	<1992Sep14.073224.1714@CSD-NewsHost.Stanford.EDU>
Date: Mon, 14 Sep 1992 09:06:15 GMT

In article <1992Sep14.073224.1714@CSD-NewsHost.Stanford.EDU> pratt@Sunburn.
Stanford.EDU (Vaughan R. Pratt) writes:

   >So with or without the Diophantine restriction, which is a purely
   >syntactic restriction with no semantic significance, your question
   >remains the same: what does it mean for ZFC+# to be a foundation for
   >mathematics?  I've already done the best I could to answer this to your
   >satisfaction, sorry we didn't make more progress.

  Have you really done the best you can? Let me try to rephrase my
question.

  As a mathematician I am, let us suppose, interested in Diophantine
equations. Now, when I attack a problem of the form "does the
Diophantine equation...have a solution", I am not particularly out to
know whether it is compatible with ZFC to assume that the equation has
a solution. Rather, I am interested in whether the equation has a
solution. If you (consistently) add to ZFC an axiom saying that a
certain Diophantine equation has a solution (and thus, perhaps,
implying that lots of interesting Diophantine equations have solutions), why
should I, as a mathematician, be interested in the resulting theory?
It is in no sense a "foundation" for my work. This extension of ZFC
doesn't in any way represent any interest of mine, and I have no
reason to believe that theorems in that extension solve my problems.

  Hence my impression that when you speak of such extensions as
"a foundation for mathematics", you are merely saying in a
peculiar and misleading way that it is possible for people to
derive consequences in these theories.
Newsgroups: sci.physics
From: mfterman@dae.Princeton.EDU (Mutant for Hire)
Subject: Re: Black hole + anti-Black hole = ?
Reply-To: mfterman@phoenix.princeton.edu (Mutant for Hire)
Organization: Princeton University
Date: Tue, 8 Sep 1992 23:43:28 GMT

In article <1992Sep8.222101.9281@math.ucla.edu>, barry@arnold.math.ucla.edu (Barry Merriman) writes:
>
>What happens if you dump some antimatter into a black 
>hole that formed from normal matter? Does it 'cancel out' part of it?
>
>Or, if I take two black holes, one made from ordinary matter
>and the other made from anti-matter, and merge them, what happens?
>Do I get a bigger black hole, or are they somehow annihilated?

There are only a few distinct properties that can be associated with a
black hole. They are mass, angular momentum, electric charge and if
you believe in monopoles, magnetic charge. (ignoring other exotic
potential charges)

Now, assuming that both black holes were made of neutral
[anti-]matter, and identical angular momenta, there would be no
observable differences between the two. All information is lost behind
the event horizon, whee!

Looks like gravity conserves even fewer quantum numbers than the weak
force.....

-- 
    Martin Terman, Mutant for Hire, Mad Scientist, Priest of Shub-Internet
    Disclaimer: Nobody else takes me seriously, why should you be the first?
mfterman@phoenix.princeton.edu mfterman@pucc.bitnet terman@pupgga.princeton.edu
"Sig quotes are like bumper stickers, only without the same sense of relevance"
From: chappell@symcom.math.uiuc.edu (Glenn Chappell)
Subject: Re: Computability of the universe
Organization: Math Dept., University of Illinois at Urbana/Champaign
Date: Sat, 12 Sep 1992 22:51:45 GMT

In article <1992Sep11.181736.5324@galois.mit.edu> jbaez@riesz.mit.edu (John C. Baez) writes:
>In my opinion this fairly pervasive notion that you can only
>"really" measure lengths that are rational numbers is an outdated
>remnant of one of the Greeks' less bright moments.  For example:
>
>Say we all measured distances with a circular roller that was one foot
>in diameter.  (I think they do something like this sometimes.)  We
>measure distances by rolling this thing along and counting the number
>of revolutions.  Okay, now we are measuring things in units of pi feet.
>If our driveway looks to be 40 revolutions long, our best guess is
>that it's 40pi feet long.
.
.
.
>Rationals are nice in many ways, but the idea
>that measurements of lengths always give rational numbers is just
>plain silly.

Strictly speaking, yes, but the idea *is* useful in practice. After
all, in real life, no length measurement is made without some
experimental error. The result of a length measurement is actually a
probability distribution - or, if you like, an interval. Since plain
ol' numbers are easier to deal with than intervals (and since, in
practice, they're usually good enough) any dense set of real numbers
will do for expressing length measurements. The rationals are dense
in the reals, and they're also generally easy to deal with, so why
not use them?

Well, interestingly enough, we usually don't. We usually use proper
subsets of the rationals.

E.g. traditionally, when the English system is used, measurements are
expressed using rationals that can be written with their denominator
being a power of 2.

Thus, English system rulers are marked in inches, 1/2's, 1/4's, 1/8's,
maybe 1/16's and sometimes 1/32's. The same goes for liquid measurements
(1/2 gallon), etc.

Now, the set of rationals that can be written as a/2^b is still dense in
the reals, so it's still good enough.

More modern practice tends toward using only those numbers than can be
expressed as a/10^b. (When was the last time you heard anyone say
"1/8 meter"?) The set of such numbers is also dense in the reals, so
it's also good enough.

				Glenn Chappell  <><
From: jtchew@csa3.lbl.gov (JOSEPH T CHEW)
Newsgroups: sci.physics
Subject: Re: It's Down to the Last Blank Check
Summary: There must be something missing.  I HOPE there's something missing.
Date: 9 Sep 92 23:29:23 GMT
Reply-To: jtchew@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

>Society needs to negotiate a new contract with the scientific community.
>This contract must be rooted in the pursuit of explicit, long-term
>social goals, such as zero population growth, reduced generation of
>waste, reduced consumption of non-renewable resources, less armed
>conflict, less dependence on material goods as a gauge of wealth or
>success and greater opportunity for self-realization for all human
>beings.  A new contract will measure the value of reasearch and
>innovation not by number of publications or citations or patents, but by
>progress toward these specific goals.  

I submit that some or all of these goals are beyond the purview of
science -- perhaps beyond any attempt at governmental management.

In fact, society being inhomogeneous and philosophy being a matter of 
taste, not everyone will agree that all of these goals are desirable,
much less on any particular plan to achieve them.  Plainly at least
one of the problems mentioned above stems from people's inability to
agree on the terms and conditions of the social contract!

Perhaps John C. Baez (a sci.physics regular whose postings I usually 
find reasonable) cut too much when he "left out some paragraphs that 
would show how he [The Hon. George E. Brown, Jr.] got to his conclusions."  
Wonder if there's anything left in the L.A. Times vending machine...

--Joe
"Just another personal opinion from the People's Republic of Berkeley"
Newsgroups: sci.physics,sci.astro,sci.math,sci.philosophy.tech
From: firth@sei.cmu.edu (Robert Firth)
Subject: Re: Hidden variable theories, was: Uncertainty Princi
Organization: Software Engineering Institute
Date: Thu, 10 Sep 1992 16:00:53 GMT

In article <mcirvin.716138484@husc8> mcirvin@husc8.harvard.edu (Mcirvin) writes:

>"Causality" here doesn't mean determinism, in the sense of "there is
>no effect without a cause" (--Dr. Pangloss); it just means that it's
>not possible to transmit a message from event A to event B where B
>is outside A's future light cone.  In this sense all of relativistic 
>quantum mechanics (at least in Minkowski spacetime) is causal.

Please delete the word "future" from the above.  In no sense does any
of relativistic quantum mechanics support the implied time asymmetry.
Newsgroups: sci.physics,sci.environment,misc.consumers
From: beckmann@spot.Colorado.EDU (BECKMANN PETR)
Subject: Re: Radioactivity and Superstition; was: Re: Are Your Light Bulbs Radioactive?
Organization: University of Colorado, Boulder
Date: Sat, 5 Sep 1992 14:49:00 GMT

>for a banana (limit 1).  But I insist on getting a video for verification.
>A polaroid might do but its probably also radioactive.  I won't pay for
>ruined teeth or dentures (signed release required).
>		dingo in boulder	(dean@vexcel.com)

Why do you people try to save a superstition-mongering medeavalist? Let him
buy an inferior fire detector that he THINKS is not radioactive and let him
burn alive, let him refuse to buy irradiated food and die of chemical 
carcinogens, let him refuse to undergo radiation when he gets a malignant 
tumor. It serves a purpose, I suppose, in showing people how common and insigni-
ficant radiation is in many man-made apppliances, but what really gets me is
when these superstition-mongering cretins spoil healthy and useful stuff for
OTHERS, like nuclear power.
    Petr Beckmann

Newsgroups: sci.physics
From: foxd@silver.ucs.indiana.edu (daniel fox)
Subject: Re: Hidden variable theories, was: Uncertainty Princi
Organization: Indiana University
Date: Thu, 10 Sep 1992 21:51:15 GMT


What has bothered me about the "killing your grandfather time travel paradox"
is that it seems to assume a Newtonian view of the universe.  I would think
that if such an experiment were attempted (by using massive rotating cylinders
or whatever) one would find that quantum mechanics would have to be used to
figure out what happened.

                                      Daniel B. Fox
                                      KF9ET
.standard disclaimer

Newsgroups: sci.physics
From: platt@watson.ibm.com (Daniel E. Platt)
Subject: Re: Wave/particle duality
Date: Mon, 14 Sep 1992 21:42:37 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM
Organization: IBM T.J. Watson Research Center
Keywords: photon,particle,dual slits,interference,quantum waves

In article <1992Sep14.201601.24668@riacs.edu>, danforth@riacs.edu (Douglas G. Danforth) writes:
|> In <1992Sep14.032341.19533@asl.dl.nec.com> terry@aslws01.asl.dl.nec.com (Terry Bollinger) writes:
|> 
|> >In article <BuJEy1.Gz5@nntp-sc.Intel.COM>
|> >bhoughto@sedona.intel.com (Blair P. Houghton) writes:
|> 
|> >> Read Feynman's Lectures on Physics, chapters 1-3 of volume III, carefully,
|> >> and if you start thinking of particles as waves go back and read them again.
|> 
|> >Dr. Feynman was even more explicit in stating that photons and electrons are
|> >particles in "QED: The Strange Theory of Light and Matter."  In that delight-
|> >ful little easy-reading book he begins by pointing out that if human eyes
|> >were about 10 times more sensitive the classic debate about whether photons
|> >were particles or waves never would have occurred.  In dim light everyone
|> >would have been able to SEE individual photons banging on their retinas as
|> >point-like flashes.
|> 
|> Are the photons point-like or is it our eyes that have point-like regions
|> of activation?
|> 
|> Consider a gentle wave rolling up a beach on which reside preset mouse
|> traps.  Some will fire (trigger) and some won't.  Is the wave discrete
|> or is it the mouse traps?

The wave itself comes in energy clumps of the size of h-bar omega (h nu if
you don't like 2 pi's).  The fields have the normal structure of wavelengths
and direction (wave-number vectors, or k-space), and frequencies (omega).
The amplitudes for each wave vector are quantum vector operators that
obey commutation relationships sort of like independent harmonic oscillators
(the guage conditions imply that things aren't quite that simple).  Harmonic
oscillators can take energy only in clumps.  In the same way, electromagnetic
fields can take energy only in clumps dependent on the wavelength of the light.
That was what the photoelectric effect showed -- light carried energy in clumps
dependent on the frequency; regardless of the intensity, red light wasn't
enough to kick off photo-excited electrons, while bluer light could.  This
was really basic to the development of quantum mechanics, and was what Einstein
was awarded his Nobel prize for.  The actual structure of the fields has
amplitudes that are quantized, of waves that are truly Fourier e^(ikx - omega t). 
So, you tell me if its a particle or a wave.

Dan
Newsgroups: sci.physics
From: m14494@mwvm.mitre.org (Mike White)
Subject: Re: Question about falling elevator...
Organization: The MITRE Corporation
Distribution: na
Date: Fri, 11 Sep 1992 17:22:09 GMT

Susan Owens writes:
> If I was in an elevator that was falling
> say 20 stories what would happen if I jumped right before I hit the
> ground.

Ignoring air friction, you and the elevator car would be in free fall.
If you could contrive to kneel on the floor of the car and kick down
just before it hit (or any other time, for that matter), you would 
impart momemtum 1/2 MV^2 to the car, resulting in an equal
and opposite momentum (thanks to Newton) being imparted to you.  The upward
acceleration of your body, and the resulting reduction of your
downward motion, would depend how fast you kicked (V) and
the ratio of the masses (M, of you and the elevator car).  In theory,
you could kick hard enough to stop your downward motion
altogether, thus saving yourself at the expense of additional
damage to the car due to its somewhat higher velocity (after
you kicked it down).  In practice, I think you would have to
be Arnold Schwarteznegger x 100 to pull it off.  Don't try
this at home.

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