HDTenEightyP/NetNews huggingface dataset:
From: andrew@rentec.com (Andrew Mullhaupt)
Newsgroups: sci.physics
Subject: Re: Lightning
Date: 21 Jul 92 22:24:50 GMT
Organization: Renaissance Technologies Corp., Setauket, NY.

In article <76253@ut-emx.uucp> johncobb@ut-emx.cc.utexas.edu (John W. Cobb) writes:
>In article <1085@kepler1.rentec.com>, andrew@rentec.com (Andrew
>Mullhaupt) writes:
>|>You hear lightning on AM radio so it isn't just DC, right? It's pretty broad
>|>band, since you can get it all over the spectrum. So it's perhaps true that
>|>initially the spark crosses the gap in some directional sense, there's a lot
>|>of AC in a lightning strike.
>|>
>Whoa, Hold on there lil' pardner. What's the spectrum of a dirac 
>delta-function? Would you call a spike AC or DC? How about a step function?
>Well just mull that around a'bit and then mosey'n back with'n your'n
>answer


When I say there's AC I mean it. You show me a pulse of DC with no high
frequencies (i.e. AC component) and I'll show you a long, long pulse.

However, lab experiments with sparks actually show significant AC - i.e.
many cycles - because there is effectively a resistor and a capacitor in
the picture.

Later,
Andrew Mullhaupt
From: bhoughto@sedona.intel.com (Blair P. Houghton)
Newsgroups: sci.physics
Subject: Re: Malnex fax to snarfy
Keywords: Quantum Radio FTL communications
Date: 30 Jul 92 00:43:10 GMT
Organization: Intel Corp., Chandler, Arizona

Just how close is Malnex to Tralfamador?

				--Blair
				  "My life is a series of postings,
				   but I've lost the ability to
				   remain in any of them..."
Newsgroups: sci.physics
From: cbettis@unlinfo.unl.edu (clifford bettis)
Subject: Re: Magnetic lenses
Organization: University of Nebraska - Lincoln
Distribution: na
Date: Wed, 29 Jul 1992 14:15:43 GMT

In <24991@dog.ee.lbl.gov> sichase@csa2.lbl.gov (SCOTT I CHASE) writes:

>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.

This is not possible for the same reason it is not possible 
(practically) to make a TV picture that looks in focus for a near 
sighted viewer. The optical phase information is lost in the recording
process (i.e. the TV camera only records intensity) and therefore the 
information necessary to reconstruct a complete image is missing. 
To make a TV capable of such feats the band width of the signal would 
have to be on the order of the frequency of light. One can also not 
adjust a projected image on a screen to appear in focus for a near or 
farsighted person for the same reason.
Cliff Bettis	
Newsgroups: sci.physics
Newsgroups: sci.physics
Subject: Re: Converting the masses
From: mcirvin@husc8.harvard.edu (Mcirvin)
Date: 23 Jul 92 15:25:34 GMT

palmer@sfu.ca (Leigh Palmer) writes:

>In article <130889@lll-winken.LLNL.GOV> dk@imager (Dave Knapp) writes:

> By the way, I've never
>been asked by a physics student why a sufficiently fast-moving rocket
>ship (or other particle) doesn't "behave like a black hole gravita-
>tionally". It does behave like a gravitating mass having the relativistic
>mass, of course.

It doesn't act at *all* like a gravitating mass at rest whose rest
mass equals the total energy of the rocket, either in its response
to or its production of gravitational fields.

-- 
Matt McIrvin   mcirvin@husc.harvard.edu   Long live short .sigs
Newsgroups: sci.physics,sci.math
From: metares@well.sf.ca.us (Tom Van Flandern)
Subject: Re: Twins Paradox Resolved
Organization: Whole Earth 'Lectronic Link
Date: Sun, 26 Jul 1992 21:05:54 GMT


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

> I don't quite understand what the difference in approaching vs. receding
> travelers has to do with it.  I still claim that there really is no
> asymmetry.

     We agree there is no asymmetry.  The version given was a symmetric
version of the twins paradox.  The main point to note is that the
differential aging effect does not depend on turn-arounds or accelerations or
frame changes.  There is "differential aging" in a one-way trip because of
lack of distant simultaneity.  T1 ages 7 months while traveling between
events "T1 encounters E1" and "T1 encounters AC".  At the first event, E1 is
age zero.  At the second event, E2 on AC (who is synchronized with E1 in the
E-frame) is aged 4 years.  There is no problem in the math here, everybody
agrees.  But people who argue that somebody needs to turn around to produce a
differential aging effect should now be able to see that is unnecessary.

     As for logical problems, one must give up totally on the concept of
distant simultaneity; and one must accept that *apparent* aging depends upon
direction of travel, approach or receding.  There is a way to avoid both of
these considerable logical compromises.  But I do not argue that they cannot
be possible, only that one must make a sacrifice (unnecessarily, it turns
out) of "common sense" to accept this interpretation of the experimental
data.  -|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.
Newsgroups: sci.physics
From: crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass)
Subject: Re: "What's New" July-24-1992
Organization: University of Virginia
Distribution: na
Date: Wed, 29 Jul 1992 18:17:23 GMT

In article <25023@dog.ee.lbl.gov> sichase@csa2.lbl.gov writes:
>In article <1992Jul29.010055.3863@murdoch.acc.Virginia.EDU>, crb7q@kelvin.seas.Virginia.EDU (Cameron Randale Bass) writes...
>> 
>>    NIH is being forced to fund study into chiropractry(?) along with the
>>    other 'alternative medicine' approaches. 
>> 
>>    As far as astrology goes, I'd think that such widespread antiscientific
>>    beliefs would be of great interest to those in the APS apparently
>>    interested in scientific purity.  
>
>Scientific organizations generally do, and should, only take political stands
>when their specific expertise lends special credibility to their claims.
>What does the APS know that every congressman doesn't already know about
>astrology?  And what do they know more than the AMA about alternative
>medicine?  It would be unethical for the leaders of the APS to put
>themselves forward as experts on medicine, even if they *do* know enough
>to judge this particular issue.  That's the role of the AMA.
>
>I think that it is a credit to the APS, not a demerit, to point out that
>they are selective in choosing issues on which to take a stand.  
>
>It seems like dale would have bashed the APS one way or the other.  If they
>said nothing, surely he would point out that they have no guts to stand
>up for what they believe in.  And if they ever did get up to complain
>about funding for chiropractry, he would point out that they were butting
>their noses in where nobody wanted them.

    Hardly.  I would applaud this with great vigour, and probably offer
    any services I could render in this pursuit.

    Of course this is beside the point, to wit: The APS, an organization
    of which I am a member, is being hypocritical in saying that their
    objection to SSF is simply the result of SSF being justified
    as science.   I suspect the true reason is a perceived funding
    competition.  

    By the way, it is certainly not my aim to 'bash' the APS.  I enjoy
    being a member.  I just do not wish to see my organization promulgate
    hypocracy over such things as petty funding competition.  Support
    of SSC is one thing.  I fully expect it, and cannot complain about
    the society supporting the activities of a large number of its 
    members.  Another society of which I am a member, AIAA, does the 
    same for SSF, which I also oppose.  However, I find appalling 
    an attempt by the APS to bash other programs under a hypocritical
    pretext.

                                 dale bass
--
C. R. Bass                                           crb7q@virginia.edu
Department of Mechanical and Aerospace Engineering
University of Virginia
Charlottesville, Virginia                            (804) 924-7926
Organization: Penn State University
Date: Tue, 21 Jul 1992 12:12:47 EDT
From: <CCB104@psuvm.psu.edu>
Newsgroups: sci.physics
Subject: Radionuclide Half-Lives

For want of a sponsor or potential "licensee," an official "Invention
Disclosure" outlining an unconventional method of forcibly changing
nuclear-decay "half-lives" has been sitting in an office gathering
dust. Although the method uses certain kinds of currently available
though, in some cases, somewhat "exotic" electronic devices (if you
consider SQUIDs, IMPATT devices, or UJTs to be "exotic"), and although
the method is described in sufficient detail in the disclosure to make
it easy to put the "invention" into operation to see if it does what it
is supposed to do, it seems to be going nowhere.
The reasons are (1) the "invention" supposedly has no commercial value
and (2) the "inventor" hasn't turned over to the authorities the basic
equations comprising the theoretical basis for the "invention," one of
which is some kind of non-source-free Klein-Gordon equation.
I don't remember the official disclosure registration number, but I
could find it out easily enough, or else, if someone or some organization
is interested in looking into the possibility of being a "sponsor" or
"licensee," let me know and I'll put you in touch.
A well known university is the current "holder" or "owner" of the "Inven-
tion Disclosure," not me. =-)
(Also, it's not sitting in *my* office, but theirs.)
Thanks,
Carey
ccb104@psuvm.bitnet
I do not speak for my employer.
From: mcirvin@husc8.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Converting the masses
Keywords: four-vectors
Date: 21 Jul 92 20:01:49 GMT
Article-I.D.: husc8.mcirvin.711748909

john@jlc.mv.com (John Leslie) writes:

>   Could someone have mercy on those of us whose college physics is
>twenty or more years in the past?  What is "four-vectors"?


-- 
Matt McIrvin, grad student, Dept. of Physics, Harvard University
mcirvin@husc.harvard.edu      mumble mumble mumble mumble mumble
From: snarfy@cruzio.santa-cruz.ca.us
Newsgroups: sci.physics
Subject: Instantaneous Communications
Keywords: Instant Communications Device System
Date: 23 Jul 92 16:09:58 GMT
Reply-To: snarfy@cruzio.santa-cruz.ca.us


 In Message-ID: <84056@netnews.upenn.edu> Matthew P Wiener writes:

>Ben Weiner sent me e-mail--that was his posting apparently.  I apologize
>for the implied accusations.  Anyway, you still don't know what you are
>talking about.
>--
>-Matthew P Wiener (weemba@sagi.wistar.upenn.edu)

        Apology  accepted.   Your  assertion  that I don't know what I'm
       talking about , however,is not very constructive toward  the  end
       of  evaluating  the  merits  of  the  instantaneous communication
       device I described in my earlier posting.  Most  of  the  private
       E-Mail  I've  gotten  on the subject is favorable and indicates a
       general willingness to be further informed about  the  underlying
       principles.   There  has  been mail critical of the suggestion as
       well, but these folks at least have the courtesy to  state  thier
       doubts  in  something  besides  personal terms. They question the
       feasability of constructing a  detector  capable  of  registering
       extremely  minute  changes in antenna current, for example. I can
       respond to this kind of doubt.

        What  I  can't deal with is non-specific assertions that I don't
       know what  I'm  talking  about.   Are  you  able  to  talk  about
       electronic  components and electromagnetic principles? If you can
       then welcome to  the  discussion.  Feel  free  to  criticize, but
       be specific, O.K.?

       Jim Ostrowski

       -(..netcom!cruzio!snarfy!)
Xref: sparky sci.physics:11865 sci.astro:8419 sci.philosophy.tech:2888 talk.religion.misc:12864
From: billn@hpcvaac.cv.hp.com (bill nelson)
Newsgroups: sci.physics,sci.astro,sci.philosophy.tech,talk.religion.misc
Subject: Re: Structure of Time
Date: 28 Jul 92 21:14:56 GMT
Distribution: na
Organization: Hewlett-Packard Company, Corvallis, Oregon USA

sichase@csa2.lbl.gov (SCOTT I CHASE) 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.
: 
: Yow!  That's a little harsh, don't you think?  Plenty of folks, sometimes
: even intentionally, post nonsense to this group.  I probably do it now
: and then by mistake.  I don't think his job should be at risk because
: he chooses to interact with us in the only way he knows how.  

Yes, we all post nonsense - once in a while, by accident or otherwise.
However, most have sense to stop (or at least ask why people are objecting)
when asked to so so. I only saw one response from the poster, and it didn't
address the complaints - just produced more garbage. 

Nor did I say that his job should be at risk. I personally believe that
would be unreasonably harsh treatment myself. However, I do believe that
a person should be willing to accept the consequences for what they post.

: 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. 

Bill
Newsgroups: sci.physics
From: snyder@henry.ece.cmu.edu (John Snyder)
Subject: Re: ... an infinite mesh of 1ohm resistors ...
Organization: Physics Department, Carnegie Mellon University
Date: Thu, 30 Jul 1992 08:38:00 GMT

In article <1992Jul28.221442.8574@irisa.fr> saouter@irisa.fr (Saouter Yannick) writes:
>In article <1992Jul28.000844.27051@mixcom.com>, ttyytt@mixcom.com (Adam Costello) writes:
>|> In article <1992Jul27.210947.5820@fs7.ece.cmu.edu> snyder@henry.ece.cmu.edu (John Snyder) writes:
>|>
>|> In each network, connect a 1 amp current source from B to A.  In the
>|> limit, we have the infinite network with a source and no sink.  I'm
>|> still not convinced, because I'm not sure "limit" makes sense here.
>|> Any comments?
>|> 
>|> AMC
>
>If "limit" does not makes sense, what can mean "infinite" ?
>
>saouter@sigle.irisa.fr


*PLEASE*--

Be careful how you edit and quote previous articles.  It was *NOT* I who
who wrote that stuff you just attributed to me.  It was Mr. Costello.
I do not object to infinite and limit.  As a matter of fact, for those
who do not like the reasoning of the analytical solution, it is easy to
check with a circuit-solving program.  Just make the grid bigger and
bigger each time you solve it, and see what is happening to the solution
as a function of grid size.

John
snyder@henry.ece.cmu.edu
Newsgroups: sci.physics
From: carl@aoa.aoa.utc.com (Carl Witthoft)
Subject: Re: Blue Sky
Organization: Adaptive Optics Associates
Date: Wed, 22 Jul 1992 12:19:47 GMT

In article <BrrMJB.Brv@acsu.buffalo.edu> mjb@acsu.buffalo.edu (Matthew J. Bernhardt) writes:
>andrew@rentec.com (Andrew Mullhaupt) writes:
>>Why is the sky blue?
>	I'll bite.  The composition of the Earth's atmosphere (four fifths
>nitrogen, one fifth oxygen) is such that incoming light is refracted to make
>the sky appear blue.
x
Get real.  It's Rayleigh scattering.
Short answer: this means particle scattering is related to wavelength,
and shortwave, i.e. blue, scatters more.  Hence blue sky.


-- 
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**
From: abreu@dcs.qmw.ac.uk (Abreu)
Newsgroups: sci.physics
Subject: Re: Physics in Portugal
Date: 25 Jul 92 19:50:49 GMT
Organization: Computer Science Dept, QMW, University of London

In <92204.132933K31412I@ALIJKU11.BITNET> <K31412I@ALIJKU11.BITNET> writes:

 > I'm going to Portugal, possibly also Spain and France via Interrail on
 > the 1st of August and should also like to visit anything worth seeing
 > as far as Physics is concerned in these countries|
 > Who can give me a hint on what there is where, and it would also be nice
 > if people knew, how one can get into those places|
 > I should be grateful for any little idea, no matter, of what kind||
 > (By the way: Any other insider-tips on lovely places to go in Portugal?)

Try asking in soc.culture.portuguese
Hamilton
Newsgroups: sci.physics
Subject: Re: Destroying the Earth
From: mcirvin@husc10.harvard.edu (Mcirvin)
Date: 28 Jul 92 15:53:46 GMT

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 Schwarzschild radius is usually cited, but that is
>rather strange, because the Schwarzschild radial coordinate does not
>measure distance. 

Perhaps it would be better-defined to ask "to what *diameter* would
we have to compress the Earth to form a black hole?"

-- 
Matt McIrvin  mcirvin@husc.harvard.edu
From: xray@endor.uucp (xray group)
Newsgroups: sci.physics
Subject: Re: HELP WITH BINOCULARS!!!!!!!!!!!!
Summary: What specifications on Binoculars mean
Keywords: Binoculars
Date: 26 Jul 92 15:15:38 GMT
Article-I.D.: das.1992Jul26.151538.21143
Distribution: sci.physics
Organization: Aiken Computation Lab, Harvard University


A binocular with a 7X50 rating will provide 7x larger images and has a 50mm
diameter objective.  10x-11x is the highest power that can be comfortably
hand held.
I believe that the field of view of 750ft at 1000yds really means that something
750ft big 1000 yards away, will be fit intoxjM~? the image ofbinoculars, I
am more used to seeing angular fields of view, for which 750ft at 1000yds
corresponds to 750/(2*pi*1000*3) = ~2.3 degrees which is consistant with 
specifications I have seen.  I got most of this info from the Orion
Telescope Center Catalogue, they have a toll free number of 1-800-447-1001
and they would probably send you a catalogue which has a binocular buying
guide in it.
From: alexa@hpnmdla.sr.hp.com (Alexander Anger)
Newsgroups: sci.physics
Subject: Re: How much does fog dampen sound?
Date: 24 Jul 92 16:13:51 GMT
Organization: Hewlett-Packard, Santa Rosa, CA

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In sci.physics, ecmtwhk@ccu1.aukuni.ac.nz (Thomas Koenig) writes:

    Wandering around in the fog recently, I wondered wether the apparent
    dampening of sound was just imagination, because of different visual
    aspects, or real.

    I've got a mechanism for the dampening:  As sound waves move past water
    droplets, the sound - induced speed difference between the droplets
    and the air means there is a resulting force on the droplets because
    of drag effects; they also move a bit, therefore there is energy
    dissipation.

    Influences would be the concentration of liquid water in the air,
    drop size distribution and sound frequency (plus the whole range of
    physical properties of the two substances involved, which depend
    on temperature and pressure).

    Has anybody ever checked this effect?
    Is it really large enough to be noticable?
    Failing that, does anyone have numbers on fog drop size distribution
    so I could do the calculations myself?
    -- 
    Thomas Koenig, ecmtwhk@ccu1.aukuni.ac.nz, ib09@rz.uni-karlsruhe.de
    The joy of engineering is to find a straight line on a double logarithmic
    diagram.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

You're in for a heck of a fluid dynamics problem here.  Good luck!
The real droplet distribution in fog is going to range from the micron
range up to macroscopic water droplets, i.e., mist or even rain drops.  
Imagine the fog as consisting of uniform thin shells of absorber material.
Using an effective density and sound absorption factor for these "shells"
will yield a much simplified calculation.  Of course, you may find that
the effective absorption factor is strongly dependent on the specific drop
size distributions, but only experiments can give you that information,
not theory (unless you're a great mathematical physicist in which case
using certain assumptions about the bulk sound absorptivity in water, you
might be able to apply statistical theories to the problem).  Obviously,
it would be nice if the effective absorption factor only depended on
the density ratio of water droplet content to air.  Then the problem would
have one of those nice, clean results that engineers love to work with.

Don't forget that you will need to have some reflectors for the sound to
bounce back from (at least the ground).

Take care.

Alex
Newsgroups: sci.physics
From: nat@netcom.com (Nathaniel Stitt)
Subject: Re: Aristotle and the Modern Physicist
Date: Sat, 25 Jul 92 10:13:42 GMT
Organization: Netcom - Online Communication Services (408 241-9760 guest)

In article <mcirvin.711994976@husc8> mcirvin@husc8.harvard.edu (Mcirvin) writes:
>
>If you don't like the world "gravity," you can use MTW's term
>and talk about "quantum geometrodynamics."
                         ^^^^^^^^

Is this related to "quantum nissancentradynamics?"


(The above is a joke, see ->  :-)
> 
>-- 
>Matt McIrvin   mcirvin@husc.harvard.edu   Long live short .sigs


nat