Newsgroup sci.physics 207016

Directory

In article <327D1603.6E43@ssl.berkeley.edu>,
Steve Geller   wrote:
>Do the "moggin" posts really belong anywhere besides sci.physics.
>
Do they belong in sci.physics?
-- 
======================================================================
Kevin Scaldeferri				University of Maryland
"The trouble is, each of them is plausible without being instictive"

--- quoting SCIENCE, 25OCT96 ---
  UPON REFLECTION
   In theoretical physics, it is sometimes the case that the solution
to one problem can be used to solve another by the proper
transformation of the system, such as switching the role of electrical
fields and charges with their magnetic analogs in electromagnetism (see
the Perspective by Girvin, p. 524). Shahar et al. (p. 589) measured the
current-voltage characteristics of a fractional quantum Hall effect
fluid and its nearby insulating state and found that the results are
essentially identical for the two states when current and voltage are
interchanged. The existence of this duality symmetry for charge and
magnetic flux may lead to new theoretical insights into the quantum
Hall effect.
--- end quoting SCIENCE, 25OCT96 ---
  Since my discovery that the finite integers, the counting numbers, or
called Naturals in mathematics are a fake and that the p-adics or
Infinite Integers are the real true integers, I have looked to physics
to straighten-out the mess. I have looked to the Quantum Hall Effect
with its strange numbers to clear the mess that is mathematics.
  Once the world sees a part of physics where the p-adics are essential
and where the finite integers just do not work, that day my friends is
a spectacular day here on Earth, for on that day physics subsumes
mathematics, just as physics subsumed chemistry in the Schroedinger
equation.
  Mathematicians have for centuries acted like high priests, acted
superior to the sciences. Almost laughable here at the close of the
20th century that mathematicians pander off as true a monsterous 100
page proof of Fermat's Last Theorem, when just around the corner the
physicists will show the birdbrain mathematicians that the Quantized
Hall Effect is written in p-adics. Essentially required p-adics and the
finite integers just do not work.
  What does all of this mean? It means simply that mathematics since
Cantor in the late 1800s has been mostly gibberish, goon squad
gibberish.
  There are many people in this world who still believe that a
mathematics proof such as say the 4 Color Mapping Proof or Wiles FLT
has more bases in reality than any physics experiment, whether you take
a shoddy one or a highly refined physics experiment. But it is this
general feeling , this general notion that mathematics proofs are
higher in trustworthiness of truth than physics experiments which has
come to a shattering end and a shattering close by 1993. All it takes
for mathematics to come rolling down from the top of the mountain is
for physics to show one area of physics where p-adics are essential.
When that happens then physics will forever more be King of the
Mountain and mathematics will grub, grub along the base of the
mountain, and whipped into shape by the physicists.
  I will look at all reports of the Quantized Hall Effect, for it is in
these strange quantum numbers, these strange fractional quantum numbers
that I believe they are strange looking only because they are not based
on the Naturals = Finite Integers but instead, 
the Quantized Hall Effect is based on Naturals = P-adics and that the
strange looking numbers are really p-adics or n-adics and their
strangeness evaporates instantly when these numbers are put into p-adics

Keith Stein wrote:
> i had assumed that since a water filled telescope certainly gives
> exactly the same angle of aberration as an air filled telescope,
How was that telescope filled with water? In particular, was the
upper surface of the water a free surface against air or a
constrained surface against glass?
------------------------------------------------------------------  
   Mikko J. Levanto            !           Tel. +358 8 551 2448  
   VTT Electronics             !           Fax  +358 8 551 2320 
   P.O.Box 1100                ! 
   FIN-90571 Oulu, Finland     ! Internet: Mikko.Levanto@vtt.fi 
----------- VTT - Technical Research Centre of Finland -----------

Ken:
> : > :I am not excusing the journal
> : > : editors; they were sloppy and apparently unprofessional in not
> : > : uncovering thie exercise in tomfoolery.
seshadri@cup.hp.com (Raghu Seshadri):
> : > We are in agreement here; but, of course,
> : > it is a lot more serious than mere
> : > sloppy unprofessionalism. 
moggin:
> :      How so?
Raghu:
> As a result of this major embarrassment
> to the field of which Social Text is such
> a prominent voice, there should have
> been a major soulsearching by other
> prominent figures of that field. There
> should have been repudiations of
> the guys involved in that scandal.
> The public (or atleast the academic
> world ) should have been given explanations
> of how such an embarrassment was not
> representative of the whole field,
> that Ross and Co do not represent the
> rest, that good, scholarly, reliable
> mechanisms are in place elsewhere where
> pomo rules roost etc etc.
     You're laboring under the misapprehension that Ross is a
"prominent figure" in the field of post-modernism.  Since he
isn't, your point is moot.  But you should embarrassed for
assuming that a single editorial slip-up could tar people who 
had nothing to do with it.
> Instead there is nothing but counter-accusations
> of charlatanism aimed at Sokal. This 
> indicates that the pomo guys are incapable
> of self-correction, self-analysis
> and objective evaluation. That is what
> is a lot more serious than mere
> sloppiness at one editorial desk.
     Here your argument is based on a falsehood -- i.e., that
"there is nothing but counter-accusations of charlatanism 
aimed at Sokal."  You need to practice some "self-correction,
self-analysis, and objective evaluation."  And by the way --
there's a good many "pomo gals," too.
-- moggin

+@+.+ (G*rd*n) writes:
| >| ...
| >Actually, I've had the idea of plagiarizing the Hoax, and
| >filling it out with material from the now-discredited
| >_Scientific_American_, my own imagination, and some of those
| >curious little books I find on tables disclosing the message
| >of the Pyramids.  I'd like to whip it into an attractive
| >farrago, and find a semi-defective copier to run off my
| >publication.  Maybe I could get Dr. Sokal to sue me.
| >
| >Well, god damn it, _somebody's_ got to do it.
meron@cars3.uchicago.edu:
| Go for it.  Submit it to a refereed science journal and we'll see the 
| result.
No way.  This gets distributed in that vast intellectual
underworld I wrote about.  Hoaxing refereed science journals
is for refereed scientists.
-- 
   }"{    G*rd*n   }"{  gcf @ panix.com  }"{

In article <55ot04$2973@bingnews.binghamton.edu>,
Alejandro Parra   wrote:
>
>I would appreciate some help with this (group theory?) problem.
>When you cross product two vectors in the three dimensional space you get as a
>result a third vector which is orthogonal to the other two. I started to wonder
>if you could try the same procedure with vectors in, say, 4
dimensions. 
>So I tried to set the matrix to get the cross product of any two of the vectors
>and the first thing I noticed was that I didn't have a square matrix to work
>with. So I formed a square matrix by using a third vector from the character
>table. And guess what? It worked! I got the "cross product" of the 3 vectors of
>the character table and as a result I obtained the fourth vector of the
>character table. The problem that I have now is this one: what did I exactly
>do?
>Did I in fact use some sort of "generalized algorithm" to obtain the cross
>product of vectors in n>3 dimensions? How would I actually get the cross
>product of only two vectors in this particular space? Any hints will be
>appreciated.
>
You are beginning to develop what are called differential forms.  I'm
not an expert, but a bunch of people around here are.  I'll fill in
some basics and let them take it from there.
The cross product is really a fake of what is called the wedge
product.  But, the cross product works on vectors, while the wedge
product works on p-forms.  So, what are p-forms?  Well, a 1-form is
just a linear functional.  That is, it takes a vector and combines
with it to give you a number, and does it in a linear way.  A p-form
does the same with p vectors with the additional condition that it is
totally antisymmetric with respect to the vectors.  I.e. if you
exchange two of the vectors, you pick up a minus sign.  (You might
also call a p-form a totally antisymmetric tensor)
So...the wedge product is a tool for taking a p-form and a q-form and
making a (p+q)-form. (In a well defined way that I won't go into)
Now, there is a natural isomorphism between vectors and 1-forms.
There is also an isomorphism between vectors in an n-dimensional space
and (n-1)-forms. Actually, there are multiple such isomorphisms and
we'll see what that means in a moment.
So, in 3-d space, you take two vectors, find their associated 1-forms,
take the wedge product of those 1-forms to get a 2-form, then find the
vector associated with that 2-form.  And that's your cross product in
3-d.  Note, we choose a right-handed convention for the cross
product.  This corresponds to that freedom in associating 2-forms with
vectors.  We could have chosen the isomorphism giving a left-handed
version.
Now, notice that 3 is the only number n for which 1+1=n-1.  This means
we have to do something different in higher dimensions.  (It's also
why there isn't a cross product in 2-d)  You picked to combine n-1
1-forms to get a (n-1)-form which then gives you a vector.  But, now
you know that you could have stuck with just two and the beast you get
is a 2-form, or an antisymmetric 2-tensor.
Hope this helped.
-- 
======================================================================
Kevin Scaldeferri				University of Maryland
"The trouble is, each of them is plausible without being instictive"

Two reasons a supercharger is less efficient:
1. Mechanical losses. Superchargers are positive displacement pums, in 
general, and turbos are centrifugal pumps. Spin a turbo by hand and it 
spins a loooooong time (if it has oil, that is, if not, it goes "screech" 
and stops). Spin a supercharger by hand and it goes "plop" and stops. 
Mechanical losses are proportional to rpm. A good tight aircraft piston 
engine supercharger could take 100 HP to turn at max power RPM.
2. Turbos recover thermal energy from the exhaust stream as they operate. 
The hot gas gives up some of its thermal energy to spin the turbo. 
(Recall that the supercharger is a leech hanging on the accesory drive of 
the engine). Heat engines' efficiency is proportional to the temperature 
difference between the combustion gases and the exhaust gases. The 
greater the difference, the more efficient (read powerful) the engine.
Spence..

In article <55scd5$hoc@rzsun02.rrz.uni-hamburg.de>,
Hauke Reddmann  wrote:
>"True" cross products only exists in dim 3+7.
Could you explain why 7-d also works?  (Also what exactly do you mean
by "true" cross product?)
My understanding was that the cross product worked in 3-d because
both 1-forms and 2-forms can be associated with vectors, thus when we
cross two vector to get a vector we are really wedging two 1-forms to
get a 2-form.  I don't see how this works in 7 dimensions, though.
However, I am but a novice at this, so I'm probably overlooking
something.
-- 
======================================================================
Kevin Scaldeferri				University of Maryland
"The trouble is, each of them is plausible without being instictive"

devens@uoguelph.ca (David L Evens) wrote[in part]:
>: Christopher R Volpe  wrote:
>: >Answers:
>: >5) There is no dependence of physical phenomena on inertial frame of the 
>: >   lab. In other words, there is no absolute motion.
>Ken Seto (kenseto@erinet.com) wrote:
>: Is this your explanation of the MMX null result?  I read somewhere
>: that SR explains the MMX null result with a combination of time
>: dilation and length contraction. How does no absolute motion explain
>: the null result?
[Evens]
>Time dilation and length contraction in other frames is the RESULT of the 
>absences of absolute motion.
If the earth moves relative to the sun, it also moves relative to
a hypothetical fixed point in space (or it is at rest relative to 
this point if the sun is doing all the actual moving).
If light's motion is merely and purely relative, then I can say that
I am moving at c and the light ray is motionless, but this contradicts
SRT which claims that nothing inertial can move as fast as light.
In SRT, after each observer sets his clocks per Einstein's def by
using light signals, each observer's clocks are different.  Since
light always travels at the same speed thru space, the only reason for
the difference is that the observers all have different absolute
speeds.
SRT has never claimed that absolute motion has no existence, but only
that it cannot be detected.  SRT says that only relative motion is
detectable.

I was asked at school do carry out an experiment (for an exhibition) to
find the rate of ice formation under different conditions. I, however,
ran into several problems. How do I calculate the rate of ice formation
in the first place? Does the anamalous expansion of water affect the
rate at which water freezes? Also, will ice's poor rate of heat
absorption greatly reduce the rate of the formation of ice? Can anyone
suggest to me an experiment to find the rate of ice formation? If there
are any other factors or problems that I should consider, I would like
to know them. 
Thanks a million.
-----------------------------
Regards :-)
           Prasanna Sritharan
-----------------------------
"Did I solicit thee from
     darkness to promote me?"
-----------------------------

See article "Time Will Tell" at  http://www.acute.com/craig

wen@infi.net writes:
>
>Okay, but the radioactivity is insignificant.  Period.
 The significance of radiation exposure is a function of the quantity 
 present and the duration and distance of the exposure.  A kg of 
 U-238 inside a control surface is less dangerous than a mg lodged 
 in your lungs. 
>     ...    It seems that you do not understand the processing
>that takes place from mine to whatever the end product.  
 I know perfectly well what the processing does, and that it does 
 not change the radioactive decay rate of U-238 or substantially 
 alter the overall radioactivity of a sample of Uranium. 
-- 
 James A. Carr        |  "The half of knowledge is knowing
    http://www.scri.fsu.edu/~jac/       |  where to find knowledge" - Anon. 
 Supercomputer Computations Res. Inst.  |  Motto over the entrance to Dodd 
 Florida State, Tallahassee FL 32306    |  Hall, former library at FSCW. 

In article , columbus@pleides.osf.org (Michael Weiss) writes:
>Starting with the easy one:
>
>    The last term: ansatz.  (I hope I typed it right.)  This is a term
>    I see often in technical papers, but no definition.
>
>The German word for `start'.  Many mathematical schemes demand that
>you "prime the pump", i.e. you pick a initial guess for the answer to
>some problem, and then the scheme tells you how to obtain better
>approximations from that.  Simple example: Newton's method.  So the
>Ansatz is your initial guess.
>
>Action is a long story.  I'll add one reference to those already
>given: Arnold, "Mathematical Methods in Classical Mechanics".
>
>Also one historical remark that may help.  Hamilton developed
>Hamiltonian optics, which deals with light propagating through an
>optical medium, perhaps inhomogeneous and not isotropic.  (Think clear
>jelly.)  This is form a geometrical optics: wave phenomena like
>diffraction are ignored.
>
>A key concept in Hamiltonian optics is the so-called optical path
>length between two points in the medium: i.e., the time it takes for
>light to get from point A to point B.  Fermat's famous Principle of
>Least Time says that light takes the path of least time, i.e., least
>optical path length.  (More precisely, it takes the path of
>*stationary* time--- but I'll let someone else get into that.)
>
>Hamilton later realized that he could recast his whole optical theory
>as a theory about mechanics.  Instead of light rays propagating
>through a medium, we have point particles following paths in
>spacetime.  The action corresponds to the optical path length.  Thus:
>
>   Hamiltonian Optics               Hamiltonian Mechanics
>
>     optical medium                     spacetime
>     path of light ray                  worldline of particle
>     optical path length                action along the worldline
>     local speed of light               Lagrangian
>       in the medium
>
>I cut a few corners on that last correspondence, but that's the
>general idea.  (More precisely, in Hamiltonian mechanics, if S is the
>action and t is the time, then dS/dt = L along a worldline.)
>
Since you got that far, I will add one more thing.  Once you got 
Hamiltonian optics, it is possible to get back to wave optics by 
relaxing the demand of stationary path and replacing it with "all 
paths are possible, weighted by appropriate complex amplitudes, 
depending on wavelength".  I won't get to gory details but when you 
take this version then the Hamiltonian ray optics is obtainable from 
it in the limit of wavelength going to 0.
Now, since Hamiltonian mechanics is formally identical to Hamiltonian 
optics, we can try the same generalization over there.  The result is 
rather interesting.  It is called Quantum Mechanics.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

In article <55u390$bcs@panix2.panix.com>, +@+.+ (G*rd*n) writes:
>+@+.+ (G*rd*n) writes:
>| >| ...
>| >Actually, I've had the idea of plagiarizing the Hoax, and
>| >filling it out with material from the now-discredited
>| >_Scientific_American_, my own imagination, and some of those
>| >curious little books I find on tables disclosing the message
>| >of the Pyramids.  I'd like to whip it into an attractive
>| >farrago, and find a semi-defective copier to run off my
>| >publication.  Maybe I could get Dr. Sokal to sue me.
>| >
>| >Well, god damn it, _somebody's_ got to do it.
>
>meron@cars3.uchicago.edu:
>| Go for it.  Submit it to a refereed science journal and we'll see the 
>| result.
>
>No way.  This gets distributed in that vast intellectual
>underworld I wrote about.  Hoaxing refereed science journals
>is for refereed scientists.
>-- 
You set your sights too low.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

Hi there,
	A couple of weeks ago, our prof. by some outworldly motivation, 
assigned the term design and thesis:
* Build a buggy of mass<250g, powered by rubber bands and cabable of pushing a 
mass=300g of specified distances of up to 6.5m.
How the hell do I do this!!!!! In theory, it should work (according to our 
prof.), but with a mass of 300g (weight<3N), the lim. static friction to 
overcome is a bit of a nuisance, especially with a car where the bands spin 
out extremely fast. 
This of course required me to put on wheels with a greater mass, and better 
traction (I used a roller blade wheel, 72mm, 78a hardness). The earlier wheels 
just spun out, and the mass + car moved nowhere.
I've tried two main approaches to storing the elastic energy:
* coil the band along its width, attaching it to hooks on the axis of the 
wheel's axle (but acceleration is too sudden, traction is difficult to deal 
with). I've tried to vary the separation distance between the end of the axle 
and the strut between which the elastic sits, to vary the tension, and hence 
the rate of unwinding.
* wrap the band along the axle of the wheel while the other end is fixed to a 
spar/dowel (however the elastic does not wrap completely around the wheel 
continously, only the attached part to the wheel does so). In this case, the 
elastic unwinds far to slowly, and the friction from the load is not overcome. 
I tried varying the radial distance at which the elastic was fixed, but more 
complications arose. However, the car moves fine on its own without the load.
In both beta cars, I have run into elastic breakage, and the cars' inability 
to push it beyond 1m when stretched to its limit.
Now that I've said a mouthful, I have two questions.
How do I approach storing the elastic energy, and is it a problem with the 
length and relative elasticity of the bands themselves?
I would appreciate ANY helpful ideas.
Thanks in advance... 

+@+.+ (G*rd*n)
> People commenting on science are not doing science (necessarily).
> No one doubts that to practice most sciences, mathematics is
> necessary; but our question is how much mathematics is necessary to 
> observe and comment on other people practicing it.  Some of these
> would-be commentators believe that they also have to read Heidegger, 
> and may have day jobs as well, so we must take care not to multiply 
> their labors unnecessarily.
     'preciate it.
-- moggin

In article  meron@cars3.uchicago.edu
writes:
> [...]
> Anybody who has been actively involved in research knows well that for 
> any good idea there are dozens of faulty ideas, thus a strick weeding 
> process is needed.
True, the number of bad ideas greatly outweighs the good ones, but
there's a difference between strict and unreasonable with regards to
the weeding process.
>                         It may hurt the egos of some people but the 
> purpose of science is to generate knowledge, not massage the egos of 
> its practitioners.  It may sometimes slightly delay the acceptance of 
> a good idea but said delay is negligible when compared to waste of 
> time and effort which may be caused by the uncritical acceptance of 
> bad ideas.
For a somewhat different perspective, see _The Art of Scientific
Investigation_, by W.I.B. Beveridge.
-- Frank Manning
-- Chair, AIAA-Tucson Section

 Daryl McCullough  writes
>In article <5oi$7PA0TUeyEwks@sthbrum.demon.co.uk>, Keith says...
>
>>Maxwell's Equations predict that the speed of light depends on the
>>electric permittivity and magnetic permeability of the medium, and the
>>velocity so predicted is a velocity relative to that medium.
>
>No, they don't. The velocity in Maxwell's equations is always the velocity
>relative to the observer.
>
>>Of course this makes no sense if you try to apply it to 'vacuum',
>>because you can't have a velocity relative to 'nothing', 
>
>Well, as I said, the velocity occurring in Maxwell's equations is the
>velocity relative to the *observer*, not relative to the medium!
BUT Maxwell predicts the normal wave equation,Daryl,
 i.e.:          d2E/dt^2 = c_m^2 d2E/dx^2
      where c_m = velocity appropriate to the medium,
                  and is relative to the medium.
i thought you knew that Daryl.
>There is no problem because (1) Maxwell's microscopic equations apply to
>the transmission of light in a vaccuum, (2) there is vaccuum almost everywhere,
>(since elementary particles are point-like) and (3) the velocity occurring in
>Maxwell's equations is the velocity relative to the *observer*, not to the
>medium.
>
>So, Keith, I know that you believe that (1), (2), and (3) are all incorrect.
>However, why don't you give some arguments for why you disbelieve them, instead
>of just endlessly repeating your beliefs?
>
I REPEAT, DARYL,
>>'there ain't no vacuum'
>>'there ain't no vacuum'
>
>>'there ain't no vacuum'
but don't take my word for this Daryl, See what MAXWELL HIMSELF SAID:
        "......It[space] may be filled with any kind of matter, or we
may endeavor to render it empty of all gross matter, as in the case of
Geissler tubes and other so-called vacua. There is always,however,enough
of matter left to receive and transmit the undulations of light......." 
     I think Maxwell and i share a very similar view of 'vacua' Daryl,
and i would like to thank Dr J. Lebeau for drawing my attention to
Maxwell's own view of 'so-called' vacua, expressed in the above short
extract from Maxwell's 1865 paper, "A Dynamical Theory of the
Electromagnetic Field".
-- 
Keith Stein

: bjon@ix.netcom.com (Brian D. Jones)
: If two clocks are started by a light source located midway of the
: clocks, and the observer is moving with respect to the light source,
: the clocks cannot be started at the same (absolute) time. 
Superfluous concept.  The only necessary concept is that they
can't be started at the same relative time (they can't be
started simultaneously WRT both standards of movement).
: They will not be absolutely synchronized 
: (as are Newton's clocks -- on paper). 
The "paper" frame is superfluous to SR.
: They will differ absolutely. 
Sure... if there were such a thing as absolute movement.
: And there are only (3) things involved:[1] the observer's absolute
: speed V, [2] the distance between the two clocks (which can be in
: terms of a measured value), and [3] light's actual (or absolute)
: speed.  No outside observers are there. 
You can go 'round and 'round all you want.
You still can't show any "need" for an absolute time by
claiming that things have an absolute movement.
That's simply "proof by emphatic assertion".
--
Wayne Throop   throopw@sheol.org  http://sheol.org/throopw
               throopw@cisco.com

Anthony Mark Swinbank wrote:
> 
> Can anyone help me with this question.
> 
> Does anyone know what the internal resistance of a lead acid car battery
> is, and why this type of wet battery is used in a car?
> 
> thanks in advance
> 
> Mark
> 
    I don't know of any other battery type that can deliver the current
necessary for turning over a cold engine.  Lead acid batteries can
deliver over 500 amps.
    Internal resistance depends on the condition of the battery's
plates.  If the voltage falls below 9 volts while cranking, the battery
should be replaced.  If I knew what normal cranking current was, the
internal resistance would be easily computed.  Unfortunately, I don't.
                                  Bill

Allen Meisner wrote:
> I am afraid that I have not made myself clear. When I say that
> light is inertialess, I mean that light can only have velocity
> in its dicrection of propagation. It can not have a component
> of velocity in any other direction.
How about electrons or baseballs? Can they have velocity components
in other directions, or are they inertialess, too?
------------------------------------------------------------------  
   Mikko J. Levanto            !           Tel. +358 8 551 2448  
   VTT Electronics             !           Fax  +358 8 551 2320 
   P.O.Box 1100                ! 
   FIN-90571 Oulu, Finland     ! Internet: Mikko.Levanto@vtt.fi 
----------- VTT - Technical Research Centre of Finland -----------

ksjung@ix.netcom.com(Kevin S. Jung) wrote:
;In  Tse Ka
Chun
; writes: 
;>
;>On Wed, 6 Nov 1996, Andrew Juniper wrote:
;>
;>> IBAN wrote:
;>> > 
;>> > ASIANS OF THE WORLD....LETS BOYCOTT AUSTRALIA.......
Yep why dont you all go home ,perhaps you and the aussies will all  be
happy 

Keith Stein wrote:
> 
> i had assumed that since a water filled telescope certainly gives
> exactly the same angle of aberration as an air filled telescope,
> this would also be true of my submerged telescope.????
If you filled the space between the primary lens and the eyepiece
of a refractor with water, you would have to aim the telescope
in the same direction as if it was filled with air. That is
because the water/glass interface would be perpendicular to the
light path. (You would have to redesign the lenses to make the
telescope work, but it could be done.)
If you filled the tube of a newtonian with water, the water
surface at the top end of the tube would we horisontal. If
you aimed the telescope in any direction but vertical, the
water surface would refract the the light. To see a particular
star, you would then have to aim the telescope in a different
direction than if it was filled with air. In fact, this would
be exactly the same as if it was submerged.
The crux of the matter is the water surface not beeing
perpendicular to the light-path.
Paul

In article <55u64s$12j0@news.ccit.arizona.edu>, frank@bigdog.engr.arizona.edu (Frank Manning) writes:
>In article  meron@cars3.uchicago.edu
>writes:
>
>> [...]
>> Anybody who has been actively involved in research knows well that for 
>> any good idea there are dozens of faulty ideas, thus a strick weeding 
>> process is needed.
>
>True, the number of bad ideas greatly outweighs the good ones, but
>there's a difference between strict and unreasonable with regards to
>the weeding process.
>
True.  Are you trying to say that the process, as is, is unreasonable 
or that some individuals may be?  If it is the first, I disagree.  If 
the second, it is a fact of life in any human activity.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

In article <55qlor$9g1@thorn.cc.usm.edu>, lrmead@ocean.st.usm.edu (Lawrence
R. Mead) wrote:
> Jacksons equation for the energy density 1/8Pi ( E^2 +B^2) is generally
> correct, provided E, B are the *net* fields at a point in space:
> E = E_1 + E_2 . Thus, your friend is correct and is using Jackson's
> equation correctly.
If the charged particle is a *point* charge, there will be a problem
with the integral diverging. This has nothing to do with the superposed
electromagnetic wave, however; it happens even for a point charge without
the wave. And, of course, if it is an extended charge distribution,
this is not an issue.
The expression for electromagnetic energy density is indeed more general
than some argument from statics might suggest; it is correct even for
situations with electromagnetic waves. In fact, it is used to calculate
the energy density of a wave even in the absence of other charges.
-- 
Matt McIrvin   

Richard Harter wrote:
> It is, by the way, not clear to me that Levi-Strauss's ur-myth is not
> priveleged.  It differs from all the others because the names are
> place holders rather than actual names.  To borrow the jargon of
> computer science it is a class definition rather than an object;
> objects (particular myths) are instantiations of the class definition
> (the generalized ur-myth).  The names and images in the ur-myth are
> not real names and images; they are simply uninterpreted tags which
> can be replaced by real names and images.  Since this is a standard
> tactic in formal logic one wonders how Derrida deals with it.
The things you call 'names' in the myths also act as metaphors or 
symbols, and therefore as functions or 'place holders.'  
Or the argument can be inverted: You'll find that each of Levi-Strauss's 
'place holders' are either (1) utterly dependent on named objects, or 
(2) relational schemas that are unintelligible without reference to at 
least one of a finite set of particular objects (e.g., the earth, a 
plant, a man, etc).  
What you call a 'class definition,' in this case, exists only as the 
rubric of a genus.  Once you attempt to use this rubric as a 'place 
holder' it no longer acts as a genus -- it simply 'stands in' or 'acts 
as' one of the finite number of species that is associated with it.  If 
you substitute a piece of paper with an 'X' written on it for an object, 
that does not allow you to posit a 'class X' that exists independently 
of that piece of paper.
-- brian

Who is Ben Bullock? I ded just see 
I am in his crackpot list - without any
analysis of my physics! This man is a criminal!
He must be stopped!
-- 
 Erkki Ahonen            Home Page: http://www.utu.fi/~erkaho
 Turku Finland           E-mail: Erkki.Ahonen@utu.fi

In article ,
hatunen@netcom.com (DaveHatunen) wrote:
>The simple fact is that science teachers simply don't know science.
>They go to a College of Education and get their degree in Education.
>There is something of a feeling in Colleges of Education that subject
>matter isn't as important as Methods of Education.
This isn't as true as it used to be.  To get a science certification
in most U.S. States these days, you need a science degree, and to keep
it you generally need a science Masters.
The problem won't go away quickly, since plenty of ed majors are
"grandfathered" as science teachers and essentially will have to
retire before they can be replaced with competent people.
I agree (as a former science teacher myself) that most of the ed
courses I took were ludicrous and time-wasting.
--
Carl Fink             carlf@panix.com      madscientist@genie.com
Dueling Modems                                  http://www.dm.net
"Any given person is an aberration"
        Michael Chary

In article , columbus@osf.org
(Michael Weiss) wrote:
> So does it even make sense to ask what sort of force tachyons could
> carry?  In other words, can you take the whole framework that explains
> a short-range force as carried by a massive particle (even in a
> simplified form, say something like Yukawa's original theory), and
> "turn it sideways", getting some kind of force carried by a tachyon?
> Or does the framework collapse into a pile of rubble if you try to do
> that?
I'd say it collapses, quite literally; the tachyon mass terms make the
theory unstable. You can stabilize it by putting in self-interactions
for the field, at which point the true vacuum of the theory becomes
a world with no tachyons!
Quantum field theories have "potential" terms which basically give the
energy density in terms of the fields. For bosons, such as the particles
we normally think of as force carriers, the term supplied by a mass is
something that goes like m^2 phi^2, where phi is the field of which the
particle is a quantum. If m^2 is negative then this will be a hill with
the summit at phi=0, and the top is not a stable equilibrium. Putting in
a term like g phi^4 will introduce stable vacua, but then the fields
that describe particles in this vacuum are the *deviations* from the
vacuum, phi' = phi - V where V is the vacuum expectation value of phi.
And the term that goes like phi' ^2 will have a positive coefficient.
In a quantum field theory with a stable vacuum, the appearance of
"tachyons" is just a sign that what you think is the vacuum is not
really the vacuum.
In fact, this is how the weak force carriers *get* their masses in the
first place, in the Standard Model. The Higgs field is "tachyonic" when
written in terms of the "vacuum" that is symmetric under electroweak gauge
symmetry. So that is not really the vacuum. The true vacuum is not
symmetric, and has a Higgs particle with m^2 > 0 (and also massive W and Z
particles, since they get masses by interacting with the analogue of V
above, as do all of the massive quarks and leptons).
-- 
Matt McIrvin   

> > ... When he says that this center "is a center that's not a
> > center," what he means is that it acts like the hub of a wheel:
> > it is the thing that keeps all the disparate stories related
> > to one another, *but it is not itself one of those stories*.
> 
> As Harter pointed out, it sounds like people are having
> difficulty with the notion of a type.
The only difficulty arises with the mystification of 'type' as if 
it's more than just the rubric of a genus.  If you put a piece of 
paper with the word "fruit" written on it next to an apple and an 
orange, all ya got is three objects.  Types don't 'exist' apart 
from their manifestation as sensible signifiers -- just like there 
ain't no oranges beyond the aggregate of oranges that have existed 
in history.
When Levi-Strauss substitutes a 'type' for a name or an object in 
his uber-myth, that signifier no longer acts as a genus -- it acts 
as a species *of* a genus.  You really have to start paying 
attention to exactly what grammar does to words.  Just because you 
call a given signifier a 'type' does not mean it acts as a genus in 
all situations.  I don't know how many times I've argued with 
people who truly believe in the eternal presence of types (or 
forms, universals, whatever); they don't understand that the purely 
generic function of a signifier takes on the function of a species 
as soon as you subject it to the grammar of most synthetic 
statements.  Just because the word itself doesn't change in 
different environments doesn't mean its function doesn't.
>> ... This presumption of a structural framework, Derrida says,
>> is *itself* the "center" that claims to ground and orient all
>> creation stories. ...
> 
> Perhaps Artese would oblige us with a definition of center that
> would help make sense of its use above...
Maybe you should just read it again.  It makes perfect sense to me.
> ... and below.
> 
> > ... Remember that Derrida doesn't "believe" in such a center,
> > he's merely pointing out the implications of this kind of
> > structural project. ...
> 
> If he wants to point "out the implications of this kind of
> structural project," he needs to review what (in his view)
> Levi-Strauss's projecct was and derive those implications from
> that.  Artese may not like Perry's summary, but I no more see
> what Artese describes (not in any scholarly sense) in "Structure,
> Sign, and Play" than what Perry describes.  Where is the point by
> point review?  Where the derivation of implications?  In short,
> where is the theory?
He needs to do this... He needs to show that...  Where's the 
point-by-point explication?...
Well, Russell, it begins on page 1 of the essay and ends about 16 
pages later.  Are you asking me where you can get a copy of it...?
It would seem that Russell has, once again, mistaken my tiny 
paraphrase for the essay itself.
About this little 'Where's the theory?' crusade:  I hate to burst 
yer saliva bubbles, but you're not going to get much 'theory' out 
of Derrida.  Deconstruction is not a theory or a method; in fact, 
it has no existence outside of a particular critical engagement 
with a particular text -- in this case Levi-Strauss's _The Raw and 
the Cooked_.  A theory is something that could be articulated 
without reference to another discourse.
> So far, we have two literary
> theorists claiming Derrida does very different things in this
> essay, and to someone from another field, it is very easy to read
> the essay and think "yes, I can imagine how *that* would happen."
Well... I suppose I won't go into the possibility that your 
reaction to the essay might have something to do with, say, *your* 
interpretive powers.
But hey, keep huntin' for them types...
-- brian

steve@unidata.ucar.edu (Steve Emmerson) wrote[in part]:
>In article <55r0tn$t91@dfw-ixnews11.ix.netcom.com>,
>	bjon@ix.netcom.com (Brian D. Jones) writes:
>> It exists whether or not  I can "define" or "measure" it.
>Why does "absolute" time or "absolute" space or "absolute" motion
>have to exist?  What evidence do you have that indicates that these
>concepts are valid or necessary to explain observed phenomenae?  What
>inertial-frame observations cannot be explained by the special theory of
>relativity?
>-- 
>Steve Emmerson        steve@unidata.ucar.edu        ...!ncar!unidata!steve
SRT does not deny the existence of absolute motion -- it just says
that it is undetectable. There's a small difference.  And SRT cannot
deny its existence or SRT would not be a testable theory.  How do
these silly rumors get started anyway?

matts2@ix.netcom.com (Matt Silberstein):
[...]
> >| But, without trying to give you a test, lets look at a recent example,
> >| the discussion of curved vs. flat space. Are you familiar with the
> >| discussion here (involving Moggin) on the topic? And are you familiar
> >| with the issues involved? If so, do you think your knowledge of math
> >| helps, or even is essential, to understanding the transformation from
> >| a euclidean to a reinmannian view of space?
+@+.+ (G*rd*n):
> >I skipped over most of that discussion, which seemed to me
> >to be an attempt to disqualify moggin from speaking about
> >physics -- another math test. 
Matt:
> There has been confusing on this issue. Both you and Moggin see this
> as an attempt to disqualify. I see it as an attempt to explain why
> Moggin's comments were, shall I say, inaccurate.
     A statement of yours like "Don't discuss this if you don't have
the qualifications" (I'm paraphrasing) is not an attempt to explain
_anything_, except in Thurber's sense.  ("Shut up, he explained.")
It's  an effort to disqualify someone from speaking.
     As an aside, the accuracy of my comments was a matter of some 
debate -- you can say what you like about them, but nothing you said
refuted my point.  I'm still not certain you knew what it was -- you
devoted yourself to arguing that I wasn't entitled to have one. 
-- moggin

In article <19961107145000.JAA02992@ladder01.news.aol.com>, jmfbah@aol.com
wrote:
> Actually. They're getting worse.  This is the first newsgroup that needs
> to use more advanced short-cut terminology for discussions.  I find that
> my eyes go cross-eyed if I'm trying to figure out what an equation means
> when the submitter is writing in MIME-format; I've stopped even trying to
> read the words in these messages.  I find that Fortran is great for
> expressing algebraic notation (like Mati said in another thread, C isn't
> his favorite form of cummunication--nor is it mine). [...]
Some people embed things in TeX format, but that has the disadvantage
of being almost completely unreadable if you don't regularly write
documents in TeX and know it in your sleep. (Some people have assumed
from the unreadability that many sci.physics posters have newsreaders
than can actually interpret embedded TeX, but as far as I know, that
isn't true-- those things are intended to be read by eyeball by TeX wonks.)
I do not think it is a very good idea to do this, beyond using carets
for exponentiation and underscores for subscripts, which are reasonable.
A while ago I wrote about a brute-force solution: scribbling out equations
as GIFs or some other, possibly simpler image format, and attaching them to
messages (I think Edward Green proposed it as a futuristic enhancement, and
I pointed out that it was already technically possible using off-the-shelf
software). Of course, this is a trifle obnoxious for people who don't have
a seamless means of examining embedded binaries in Usenet posts, and it
requires that the poster have hardware and software with which to
scribble.
Lately, I've been doing a lot of math in Mathematica, and I'm starting
to think that Mathematica's plain-text input notation might actually be
a pretty good way to express things in human-readable, yet ASCII, format.
It has syntax for everything most people are likely to want; algebra,
calculus, and standard names for every function that ever got named
after somebody. But it is, I suppose, still a bit opaque to the
uninitiated. The advantage over TeX is that since it is a language for
expressing formulae rather than expressing the appearances of formulae,
there isn't as much extraneous matter such as the backslashes that
TeX uses to distinguish plain old letters from other things. Also, it's
more verbose to avoid ambiguity. So instead of
$$ \int^\infty_0 i/(x^2 + 46) dx $$
or (prettier to print, worse to read)
$$ \int^\infty_0 {i \over x^2 + 46} \, dx $$
you type
Integrate[ I / (x^2 + 46), {x,0,Infinity} ]
The Mathematica version seems slightly more readable to me, but I
suppose it is a matter of taste. There are some slightly unusual
conventions such as that capitalized I.
(On the other hand, I just realized that I don't remember what the
"not equal to" symbol is in Mathematica, which might be a bad sign.)
-- 
Matt McIrvin   

Christopher R Volpe  wrote[in part]:
>Brian D. Jones wrote:
>> 
>> throopw@sheol.org (Wayne Throop) wrote [in part]:
>> 
>> >: bjon@ix.netcom.com (Brian Jones)
>> >: given any two events, each observer will find a different time between
>> >: them.  This tells us that their clocks all read differently at these
>> >: same two events.  And yet the events themselves obviously can have
>> >: only a single time between them.
>> 
>> >That doesn't follow.  Consider: given any two points on a plane,
>> >each observer will find a different delta-x between them.  This tells
>> >us that their x-coordinate rules all read differently at these
>> >two points.  And yet the points themselves obviously can have
>> >only a single delta-x between them.
>> 
>> >Bjon simply ignores that the two cases are exactly and precisely analogous.
>> >He says, yes, there's no absolute direction, but there must be absolute time.
>> >Yet he argues for the necessity of "absolute time" via a schema that
>> >is obviously vacuous and a non-sequitur.
>> 
>> Nope, Throop, there was no "argument for absolute time."  Apparently,
>> there's no way (within a finite time) to get the message across to
>> you.
>Bjon, you JUST GOT THROUGH SAYING that the events themselves "obviously
>can have only a single time between them", which is a claim of absolute
>time interval, and now you deny that you had argued for absolute time.
>Make up your mind.
Let's see, how can I put this? We do not have absolute time at our
disposal, but it does of course exist.  We just can't use it.
Although each and every clock has an actual intrinsic "beat," we have
no way of knowing or determining what this actual beat may be.  This
is because WE slow down with the clock.  When you say "absolute time,"
it usually means "We possess it and can use it," and this is obviously
not true, so I agree with you that we don't "have" it.  But it does
have a very real existence as shown by the actual beat of each atomic
clock.
>> 
>> >The point is, it is SR's model that two events do NOT have
>> >"only a single time between them".
>> 
>> >: The invariant interval has no physical meaning, being a mere
>> >: mathematical construct.
>> 
>> >This claim is exactly as convincing as a claim that "distance" has
>> >no physical meaning, being a mere mathematical construct (x^2+y^2).
>> >I've lost count of the number of times I've pointed out to bjon the
>> >physical meaning of the interval: it's the number of times a clock will
>> >tick in uniform motion between two events.
>> 
>> You're referring not to the invariant interval but to "proper time."
>The invariant interval *is* proper time!!! The interval in question is
>the space-time interval between two events. Note that in the coordinate
>system in which an observer moves inertially between two events in
>space-time, the two events take place at the same location (by
>construction, each event occurs at location (0,0,0), i.e. the origin, of
>the observer's spatial coordinate system). Since they take place at the
>same location in this system, the invariant interval has only a temporal
>aspect in this system. The entire spacetime interval is a time interval
>in this coordinate system, and we call this time interval "proper time".
>"Spacetime interval" between two events is synonymous with the proper
>time experienced by an observer moving inertially from one event to the
>next.
>Chris Volpe
The invariant interval (II):
Observer A finds two events to be 1 LY and .0583 Yr apart.
Observer B finds the event to be 1.4364 LY & 1.0328 Yrs apart.
A's II� = (1 LY)� - (.0583 Yr)� = .9966
B's II� = (1.4364 LY)� - (1.0328 Yrs) = .9966
What physical meaning is there to the .9966 result?  It is a 
combination of distance and time, each squared.  What meaning can
a time squared have? And what about subtracting this time squared 
from the distance squared?
OTOH, the proper time for the two events is the time recorded by a
single clock that happened to be at each event (by moving between
them). This value depends on how fast the clock had to go, which in
turn depends upon how far apart the events were in space, and upon the
true time between them.  Obviously, for many events, there's not
enough time for a clock to "span" them, even at lightspeed, so there
would be no proper time for the events. This is the case above.

In article <55tvte$6ms@panix2.panix.com>, +@+.+ (G*rd*n) writes:
>>+@+.+ (G*rd*n) writes:
>| >| >Very simple things; I can visualize a body moving in an
>| >| >ellipse about another body, for example, and moving more
>| >| >rapidly when near the other body then when far from it.
>
>meron@cars3.uchicago.edu:
>| >| Why an ellipse?
>
>+@+.+ (G*rd*n) writes:
>| >As I said before, explanation ("why") is a rhetorical
>| >process.
>
>meron@cars3.uchicago.edu:
>| No, not at all.
>
>All right, you could make a physical model or a diagram that
>was explanatory.  In fact, I will do so in a moment.  But in 
>the area of using mathematics on scientific problems, where we
>seek explanation, we're usually talking about finding formulas 
>which model some aspects of some sets of phenomena.  Describing 
>how we abstract the sets and the aspects tends to be a textual 
>(rhetorical) procedure, and the formulas themselves are textual.
In other words you use "rhetorical" as synonym for "textual" and take 
any symbolic means of conveying information as textual.  In short,
conveying information equals rhetorical.  Defendable, but not very 
useful.
What you've to realize is that there is a huge difference between 
being communicated a formula which is the final result of a 
calculation and going yourself through the calculation with general 
enough assumptions.  In the second case you get not just what's there 
but also what could've been there if this or other assumption would 
change.  What matters and what doesn't.  What's constant and what may 
change.  That's a wealth of information that's being lost if you just 
get your final result.
>
>+@+.+ (G*rd*n) writes:
>| > By the time of Kepler, we already have a
>| >rhetoricization of planetary movement; it is an ellipse,
>| >that is, a particular geometrical form which we have a good
>| >bit of text about, and in addition Kepler observes that a
>| >line drawn from one body to the other sweeps out an equal
>| >area in equal time.  
>
>meron@cars3.uchicago.edu:
>| Observation and understanding isn't the same thing.  A person with 
>| some curiosity may ask some questions here, like:
>| 
>| 1)  Does it have to be an ellipse?
>| 2)  If yes, does it tell us something about the force or will it be an
>| ellipse for any force?
>| 3)  Is it possible to throw something into space in such way that I'll
>| get a close orbit which isn't an ellipse.
>| 
>| The third one is especially interesting since, would the answer be 
>| "yes" then the obvious next question would've been "so what was the 
>| specific mechanism which forced all the planets into elliptical 
>| orbits" while if the answer is "no" then this question doesn't need to
>| be asked at all.
>| 
>| Of course there are way more questions that can be asked.  I won't 
>| even start getting into it.  But I would hardly call memorizing the 
>| sentence "planetary orbits are ellipses", understanding.
>
>That would be rhetorical: the memorization of a text, in this
>case a rule.  
>
>Let's suppose, however, we want to teach a child how the Moon 
>moves around the Earth.  We find an apple tree out in the 
>fields of England, and there's conveniently a pale moon hanging
>in the late afternoon sky.  There are several apples scattered
>on the ground.  We pick one up and encourage the child to notice
>that, in certain positions, the shadow on the apple is similar
>to the shadow on the moon.  Now we throw the apple a short
>distance.  It moves in a curve and strikes the ground.  Then
>we throw another one a bit harder, and of course it strikes the
>ground further out.  Now, the child knows that the Earth is a
>ball; so when we ask her what would happen if we could throw the 
>apples as hard as we wanted, and kept throwing them harder and 
>harder, she will correctly guess that eventually one will either 
>circle the earth or fly off into space.  (We may have to digress 
>to take care of atmospheric friction.)  Now we can point out the 
>similarity of the moon to this apple thrown very hard: it falls 
>around the world.
>
>This child now intuits something about the motion of the Moon
>around the Earth, which can be generalized to the whole Solar
>System.  Is this _understanding_?  Perhaps we should apply the
>compared-to-what test: it's better than belief in crystalline 
>spheres, at least.  It's true we haven't figured out _why_ the 
>orbit is stable but it isn't counter-intuitive to think of it 
>as stable; cyclical processes are common in Nature and larger 
>animal brains are well-programmed to intuit them.
No, as I've told you already, for almost any imaginable force you 
won't get a closed orbit.  There is nothing intuitive here.  And, if 
it is a closed orbit, then why an ellipse.  Again, nothing intuitive 
here.  There is an infinite variety of possible closed curves.  What 
you're trying to claim is that there is an intuitive connection from 
"there exists an attractive force" to "as a result we've elliptical 
orbits".  But, it is not true.
>
>g*rd*n:
>| >I don't see why the detailed mechanics of computation are 
>| >so important to your understanding of understanding, but we
>| >keep coming back to it ("explain").  Why can't people take
>| >them on faith, since they seem to work?
>
>meron@cars3.uchicago.edu:
>| We can just take everytjing in the world on faith, "things are the way
>| they are".  Easy, no need for science.  If you're satisfied with this 
>| and don't ask for more, fine.  I'm not.
>
>People commenting on science are not doing science (necessarily).
>No one doubts that to practice most sciences, mathematics is
>necessary; but our question is how much mathematics is necessary to 
>observe and comment on other people practicing it.  Some of these
>would-be commentators believe that they also have to read Heidegger, 
>and may have day jobs as well, so we must take care not to multiply 
>their labors unnecessarily.
But of course.  And I did never claimed that everybody should be 
studying and doing science.  That's not the issue.  We were discussing 
the need for knowledge of math in order to understand physics.  You 
seem to believe that one can intuitively understand physics without 
any math.  I disagree.  Beyond some level math is needed and without 
it what you call understanding becomes just memorization of phrases.  
If you just memorized "gravity is an attractive force" and "the 
planetary orbits are ellipses" then when I'll ask you "what would 
happen if the force is proportional to inverse distance instead of 
inverse distance squared?" you'll say "well, since it is still 
attractive, we'll got some different ellipses".  Which is totally 
wrong.  But without calculus you won't be able to do better.
Of course you may say "but I don't care to do better".  Sure, no 
problem, you may go through your entire life (most people do) 
without ever having any use for such knowledge.  But, when you start 
commenting on science, such knowledge may be relevant (doesn't have to 
be, mind you, it depends on the specific issue).  And if it happens to 
be relevant and you don't have it, chances are that your comments will 
be either wrong or irrelevant.  Which doesn't mean that you're 
disqualified from commenting.  Nobody is disqualified.  It just means 
that your comments may not be very valuable, that's all.
For example, if you comment on the differences between classical 
mechanics and special relativity and it turns out that you don't know 
what the Galilean and Lorentz transformations are, it is similar to a 
person commenting on the differences between poker and bridge without 
knowing the rules of either.  Such person is still free to comment 
(hey, it is a free country, isn't it) but one wouldn't expect the 
comments to be very meaningful.  And, would he made these comments to 
a bunch of card players, they would ask him "just a second, do you 
know what the rules are?"  Which wouldn't be a power game or an 
attempt to assert dominance, just a check of qualifications.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

"Paul B.Andersen"  wrote[in part]:
>Brian D. Jones wrote:
>> 
>> An observer has two x-axis clocks that have not yet been started.   He
>> passes a light source.  This source is energized midway of the clocks.
>> 
>> Since the rear clock moves TOWARD the light, and the front clock moves
>> AWAY FROM it, the clocks will not be started at (absolutely) the same
>> time.
>> 
>> Given that the clocks cannot have the SAME reading at (absolutely) the
>> same time, what will their readings be at (absolutely) the same time?
>> 
>> Fill in the blanks:
>> 
>> _________________                                  _________________
>> 
>> Rear Clock Reading                                 Right Clock Reading
>> 
>> NOTE: You cannot put zero in both places.
>In SR there is no such thing as absolute time, so SR can 
>obviously not give an answer to what the readings of the 
>clocks are at absolutely the same time.
SRT has an answer, and it is given by Einstein's definition of
synchronization.  There is a definite way that clocks are synchronized
in SRT.
"How definite?," you may ask. Well, in Newton's View, clocks are
absolutely set, and yield a variable 1-way lightspeed.  OTOH, in SRT,
clocks are relatively set, and yield a constant 1-way lightspeed.
Therefore, you can answer my above question by simply showing us how
the above two results happen (on paper).  Show each step, giving the
clock readings (algebraically).
>According to Newton however, we can give an answer which we 
>know will be wrong for high relative speeds between source
>and observer.
>As I am sure you know, by rephrasing the question, omitting
>the "absolutely" and inserting "in the inertial frame in
>which the observer is stationary", SR could give an answer,
>and you know what that is.
>What is your point? 
>What is _your_ answer? According to which theory?
> 
>SR is a well defined, consistent theory. I am now refering to SR
>as the rest of world understands it, not what you say SR should
>be, or what you say SR is (whatever that may be), or PR or SRT.
>As all consistent theories, SR can only be falsified by showing 
>that its predictions do not match experimental evidence.
>When comparing the predicted values of entities with the 
>experimental values of the same entities, you obviously have
>in both cases to use the same definitions of the entities as 
>per the theory. When SR predicts a time, you must in the experiment
>measure the entity time as defined by SR.
>What you are doing, is asserting an absolute space, absolute 
>velocity and absolute global time. That is your right. 
>That you are not able to define what those mystical entities 
>are, or how they could be observed, is your problem.
>But when you over and over and over again claim SR to be 
>wrong because "time" and "velocity" in SR are defined
>differently than _your_ mystical entities by the same name,
>then you only display faulty logic.
>Or have I misinterpreted you?
>Do you not claim SR to be wrong?
>Paul
Oh, I feel sure SRT is correct, but grossly misunderstood.
All the theory says is "No absolute motion detection, not even by
optical means" (classical physics already had mechanical means).
So far, SRT has seemed to hold, but I am not sure about the CBR.
All I am saying above about the clocks is that even in SRT there are
real clocks with real readings, etc.

-----BEGIN PGP SIGNED MESSAGE-----
These articles appeared to be off-topic to the 'bot, who posts these notices as
a convenience to the Usenet readers, who may choose to mark these articles as
"already read".  It would be inappropriate for anyone to interfere with the
propagation of these articles based only on this 'bot's notices.
You can find the software to process these notices at CancelMoose's[tm] WWW
site: http://www.cm.org.  This 'bot is not affiliated with the CM[TM].
Poster breakdown, culled from the From: headers:
  1 Archimedes.Plutonium@dartmouth.edu (Archimedes Plutonium)
The 'bot does not e-mail these posters and is not affiliated with the several
people who choose to do so.
@@BEGIN NCM HEADERS
Version: 0.9
Issuer: sci.physics-NoCeMbot@bwalk.dm.com
Type: off-topic
Newsgroup: sci.physics
Action: hide
Delete: no
Count: 1
Notice-ID: spncm1996311190757
@@BEGIN NCM BODY
<55rcgj$lvh@dartvax.dartmouth.edu>	sci.logic
	sci.physics
	sci.math
	rec.arts.movies.current-films
@@END NCM BODY
Feel free to e-mail the 'bot for a copy of its PGP public key or to comment on
its criteria for finding off-topic articles. All e-mail will be read by humans.
-----BEGIN PGP SIGNATURE-----
Version: 2.6
iQCVAwUBMoIzj4z0ceX+vLURAQE1mAQArth5+W+uv1G4IwsYRQW4tV796nIXa3kn
X4y1WcDVjbKslIfY8a9TmlAIFhl2JPBQo7jAIKjI9d73wp0+igYZnh5wf9cd3PGf
mkJCCYdZc01Mono62Z1EhixbWSj4P2/P2EEGc0+tcaTsDyZ6pwRPU+p7TMWhtcEa
Whk6+elBpYc=
=5Qwi
-----END PGP SIGNATURE-----

Cees Roos  wrote[in part]:
>In article <55r0tn$t91@dfw-ixnews11.ix.netcom.com>, Brian D. Jones
> wrote:
>[snip]
>> It exists whether or not  I can "define" or "measure" it.
>[snip]
>>      �� �J ��
>> bjon @ ix. netcom. com
>> 
>Now you are doing it once again!
>What you state in your sentence amounts to:
>  The something here, of which I don't know what it is, and which I
>  cannot observe, is here anyway.
>How can you know?
>-- 
>Regards, Cees Roos.
>Everyone is clumsy at his own level. 
Einstein does not deny the existence of absolute motion, but the
detection thereof.

Spence Spencer wrote:
> 
> Two reasons a supercharger is less efficient:
> 
> 1. Mechanical losses. Superchargers are positive displacement pums, in
> general, and turbos are centrifugal pumps. Spin a turbo by hand and it
> spins a loooooong time (if it has oil, that is, if not, it goes "screech"
> and stops). Spin a supercharger by hand and it goes "plop" and stops.
> Mechanical losses are proportional to rpm. A good tight aircraft piston
> engine supercharger could take 100 HP to turn at max power RPM.
> 
> 2. Turbos recover thermal energy from the exhaust stream as they operate.
> The hot gas gives up some of its thermal energy to spin the turbo.
> (Recall that the supercharger is a leech hanging on the accesory drive of
> the engine). Heat engines' efficiency is proportional to the temperature
> difference between the combustion gases and the exhaust gases. The
> greater the difference, the more efficient (read powerful) the engine.
> 
> Spence..
Not to argue, here, I just want to add my 2�:
I like my Corrado G60 because I get the boost right away.  I've driven
my friend's turbo Ford Probe and it just didn't feel natural.  When I
was driving his car, I had to anticipate the power coming on a few
seconds later.  Though going back to my car felt more natural, like I
had a V6.
Yes, the G60 does "soak" up ~14 hp, so the car feels sluggish at low
rpms, though the G60 returns more then 50hp when above ~2,000 rpms. 
There is quite a bit of technical information that would be just what
people adding to this thread are looking for. 
http://www.corrado-club.com/gallery/informational/     contains a
technical article about the G60 supercharger and why VW decided on it. 
There are two files, though they are a little hard to read due to they
were scanned then compressed, but they are readable.  One other thing,
turbos need to be kept cool.  As my friend has to idle his car for about
40 seconds before turning the car off.  This is to let the turbo cool
down, superchargers do not require this, as the article points out.  
I'm happy with the trade off decision VW made, personally, I like being
able to punch it and go and not have the boost kick in........later.
-- Alden
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
'90 Green-Pearl      |   C:\ONGRTLNS.W95     | VWs owned:
Metallic Corrado G60 | Windows '95 = Mac '84 |         '90 Corrado G60
w/black leather, ABS | Pentium or PowerPC?   |         '84 Quantum GL5
and P-Chip;CCA Member|   DO THE MATH!  I don't expect you to understand,
http://www.hooked.net/~acates/mycar/mycar.html  it's a Volkswagen thing!
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

In article <3FTeEQ$lC5@bbs.phys.ntu.edu.tw>,
Schreiber  wrote:
>
>  so if the medium is ununiformly polarized,  the total charge density must
>
> include "free charge" density and "bound charge" volume density
>
> BUT why can we ignore the bound charge "surface" density ???
>
>  Doesn't it also contribute to the "total" charge ???
>
Yes, it does.
div E = rho_total
div D = rho_free
div P = -rho_bound
E = D - P    
Taking the divergence of this gives:
rho_total = rho_free + rho_bound
(to within factors of 4pi, epsilon_0, or whatever depending on what
system of units you use--which would only confuse things for the present
purposes).
Sounds like you're confusing E and D.  E is produced by all charges in the
system, regardless of whether they're "free" or "bound."  D is produced by
free charges only.  P is related to bound charges only.  Introducing D is
basically a way of considering the world to consist of free charges and
materials, without explicitly figuring out where all the bound charge is.
The surface of a dielectric tends to have a singularity (to first approx.)
in div P, resulting in an infinitesimally thin bound surface charge.
This contributes to E according to the very same set of equations that a
nonuniformly polarized material contributes to E.
Have fun,
breed