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Somewhere in my life I sucked up this statement about quantum mechanics:
"the fact that in QM you need a*b terms to describe a two body system (whereas
in Newtonian mechanics you only need a+b terms) is the sole reason for
all the weirdness in QM"
Someone tell me where I could have read this, if it is correct, and what
it means (ie. how the heisenberg UP stems from this, etc)?
then tell me why my brain remembers that, and nothing else.
"TM"
thanks

Christopher Michael Jones wrote:
> Besides,
> there is also the possiblity that none of this matters anyway.
That's for sure.
> If the
> universe is really a "multiple minds / multiple reality" universe, then
> all these things can happen (including the hard encounter / "paradox")
> without a paradox acutally occuring.
Well, I was thinking of possibility: that time travel only exists in comic 
books and movies.
I can't remember if I posted this or emailed it to someone.  But I'd like to 
know why anyone thinks that time travel is possible.  I know that Einstein 
theorized that if we travel REALLY fast, it will seem like we were traveling 
for a short time, but when we stop we will find that the rest of the world 
has experienced a much greater time.  I suppose that the faster we travel, 
the greater the time difference will be.  But how has this theory been 
tested?  (I've only heard of this theory.  I dont know why Einstein thought 
this would happen.  I just don't know anything about this stuff.)
But what I don't understand is how people decided that, because of that 
theory, we must be able to go forward and backward in time.  That's quite a 
bit different.  I mean WAY different.  Is there another theory, based on 
Einstein's, that explains this?  (In which case, it's a theory based on a 
theory, not a theory based on fact.)  Is the other theory completely 
unrelated to Einstein's?  Who is the author of this other theory?
I really wish I knew more about this stuff.  Are there any "E=mc2 For 
Dummies" type of books out there that I can read?

In article <55tcou$gmh@daily-planet.nodak.edu>,
thweatt@prairie.nodak.edu (Superdave the Wonderchemist) wrote:
> I just thought I might clear some things up.  I am a Ph.D. candidate in 
> quantum chemistry, so maybe I might know a little about quantum mechanics.
[snip]
> However, the Schroedinger equation for the Hydrogen atom finally gave us 
> the model we were looking for.  It is the EXACT solution to the energies 
> of the Hydrogen atom and Hydrogen-like ions (He+, Li++, etc).  The 
> Schroedinger equation can be solved exactly only for one-electron 
> systems.  It has the form: H(psi)=E(psi)  where psi is the wavefunction 
> (yes, that's right, electrons ALWAYS and ONLY travel in waves, even if 
> the electrons are bound to a nucleus), H is the Hamiltonian Operator, and 
> E is the energy of the system.
[snip]
> -Superdave The Wonderchemist
Well, I think you might need to do a little more studying before your
thesis defense committee tears you apart for claiming that the
Schroedinger equation is an EXACT solution for the hydrogen atom.
At the very least you ought to go as far as the Dirac equation, which
includes the relativistic effects that give you hyperfine structure
in the atomic spectrum.
And if you really want to get precise, you need to go to a full
quantum electrodynamics treatment, with quantized fields and the
whole works.  Hell, even QCD enters into the picture a little bit with
virtual particle effects -- QED breaks down around the 12th decimal
point in the electron's gyromagnetic ratio because of this.
The point is that almost nothing in physics is EXACT.  There are
just different degrees of approximation, from back of the envelope
calculations down to the umpteenth decimal.  Otherwise, I'd like to
commend you on a nice summary of the fundamentals of atomic quantum
physics.  Thanks.
+------------ Edward Keyes, mistered@1stresource.com -------------+
|............. http://www.1stresource.com/~mistered/ .............|
|.... DaggerWare: "small, sharp, and with a heck of a point!" ....|
+- "A little inaccuracy saves a world of explanation." C.E.Ayres -+

hatunen@netcom.com (DaveHatunen) wrote:
>In article <3281EC2A.6905@slc.unisys.com>,
>Helge Moulding   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.
I'm not sure about Arizona, but in California you have to have a degree 
in a subject or related field to get a credential for the secondary 
schools.  Be careful how you swing that broad brush!  My degree happens 
to be in Mechanical Engineering and is backed up with 15 years of 
real-world experinence.  I know science, have made my living with 
science, and now I help others learn science.  Science teachers like me 
are not rare, and we may indeed be the majority.
>I thought the year I spent in the University of Arizona College of
>Education was one of the silliest experiences I had ever gone through.
>Through an odd set of circumstances indirectly involving the Shah of
>Iran, I taught full time before I had earned teaching credentials (and
>then did my student teaching in the very classroom where I had
>previously taught). The experience in the College of Education so
>disheartened me that I never did apply for a regular teaching
>certificate, although I did substitute for several years.
Circumstance make for odd situations.  The critical shortage of science 
teachers has allowed some unqualified persons into the field, but there 
are even more people who have made a commitment to the profession.  I 
view the teaching school experience as a kind of institutional hazing 
process.  If you can put up with the credential program, you can probably 
put up with the hassles of teaching!
It's good that you recognized that teaching was not your "cup of tea."  
Many people have made that determination after they were already stuck in 
the profession, to the detriment of both themselves and their students. 
George Lyle

>meron@cars3.uchicago.edu wrote:
> >> So, to put it in one sentence, math is dealing with deducing outcomes
> >> from known axioms.  Science is dealing with deducing axioms from known
> >> outcomes.  That's an essential difference.
If you accept that Fundamental Science is the part of science specifically 
devoted to deducing the axioms for known (observable) outcomes and `only 
gradually closes in' to axioms sufficient for a consistent description for our
observations (or `per definition' becomes an application of whatever science
`delivers the axioms'), I'd like to paraphrase:
Math is occupied with detailing what we could worry about, Fundamental Science
instead with relating this to our observation that we don't worry about a lot. 
Leonard Timmons wrote:
> When a measurement becomes so inaccurate that it contains
> an infinitesimally small amount of information, then it
> is declared an axiom.  From a collection of such highly inaccurate 
[may I say instead: "incomplete"?] 
> measurements of the universe, highly accurate predictions can be made.
True (and fantastically sucsessfull for all `non-fundamental' science).
But: it is dangerously >>tempting to accept<< that axiom as `one of those 
Fundamental Science looks for' - which has been unsuccessfull repeatedly 
(Physics example: `modelling' air as continuum instead as `molecular gas') 
and is `suspect by experience', and seems to have led Physics into trouble
recently. Can we do better?
By capturing `more than an infinitesimally small amount of information'
(`perhaps even all information') in axioms (holism)? This may be `logically 
sound' but how could it be `technically feasable' (as viewed from this angle)?
Instead I propose that >>only the method of verification of a theory can be
the source of axioms<< in `observational sciences', i.e. the >>Principle of 
Consistency<<, the mere fact that paradoxa are not allowed to occur, similar
(or if you will, the reverse) to how Mathematics operates trivially.
Trying to apply it (even and specifically as basis for Physics) makes one 
(little :) problem stand out: what's the predictive power? (That question is 
`not really' acute in Mathematics except you start `theorizing about axioms'). 
Given initially the `complete set of all observations' (a consistent axiom set
by definition of `scientific honesty' of `independent observers'), is there a
`boot-strap method' to reduce it to `useful' axioms without creating paradoxa?
Yes! By (mathematically) modelling a `scheme' of how (pairs of) `independent 
observers' can possibly agree that they are >>indeed consistent<<, even if they
have a priory totally arbitrary `scales of how to rate' their (individual)
observations. There are methods to >>`synchronize' or `correlate'<< scales or
sets of observations, and only what's >>not invariant<< in those models will 
serve as `reduced axioms', non-paradoxial by construction.
This may sound completely vacuous, but it is not: it can be applied to 
relativistic and to quantum Physics (both being `ideally suited' to describe or
model `synchronization' resp. `correlation' and apply the suggested method in
a rigerous way - publication of my QM-treatment pending :), and I'm pretty sure
that similar concepts are applied in all `statistically observational' sciences
as economics, biology, sociology - you name them.
Of course, the `boot-strap' will not work for certain cases, the set being too
trivial, the model and its `invariants' being `worse than nothing', but there 
you have it: one axiom and one method - go play. And have a nice weekend.    
Is this an old/insufficient/unsound/incomprehensible idea?
Appreciating your comments (echoes of a shot :),              Frank  W ~@) R
Whatever is not forbidden in Physics is mandatory.  
(after R. Feynman) 

Paul  wrote:
>> Re: Attract Lightning Strikes??
>
>I saw a special program on TV the other day about lightning.  They
>said that  40% of the people in the US who are struck by lightning
>are golfers.  If you want to attract lightning, try playing golf
>in the rain.  Make sure to wear your shoes with metal cleats
>and hold your golf club high.
Taking shelter under the only tree for several hundred yards might have 
something to do with it too!
Our local weather service PR representative gives a "severe weather" 
slide show, one slide of which shows a woman with her 40cm long hair 
standing at right angles to her head.  This slide usually gets quite a 
few laughs.  the rep then tells the audience that the film was developed 
from the camera found  with the bodies of the woman in the slide and the 
woman who photographed her.  The hair standing on end was evidence of the 
charge building up before the lightning struck.
Be careful.
George Lyle

>> moggin@nando.net (moggin) writes:
>>> I gather both of those statements
>>> are true from your perspective, and I'm not arguing differently --
>>> but their truth depends on your concept of generalization. That is,
>>> you can describe both hills and plains in terms of a wider concept,
>>> allowing you to say that you've "generalized" from one to the other.
>>
>Matt:
>> I think that what we are doing. In the case of CM->GR "we" added the
>> concept of curvature to space and generalized it. Remember that Newton
>> did not talk about flat space, they did not have the concept that
>> space itself could be curved. GR adds the concept and shows how the
>> curvature varies.
Moggin:
>     No argument there.  Note that since Newton had no concept of
>curved space, you couldn't generalize _on_ or _from_ his thinking
>to get to relativity, which does.  (I'm speaking of the ordinary
>sense of "generalize.")   But you can add a new concept to create
>a different theory which is more general than Newton's (which is
>what "generalize" means to you).
Good point.  Since my name was mentioned (in some text I've deleted),
I'll butt in for a second to try and emphasize something.  There is no
theory about the direction in which "generalization" is understood to
develop.
A generalization necessarily *obscures* particulars in order to form a
concept which collects many diverse things.  Without generalization
there could be no conceptualization.  This is what Moggin's type of
generalization (i.e. "hamburger" as a kind of thing) was pointing
towards.  But this means that "conceptualization" has a kind of
momentum.  Can anyone make a coherent argument about why, starting
from raw experience (if such a thing were possible) one couldn't come
up with vastly different notions of Nature, completely alien to our
"objectivists", which were yet not at odds with empiricism?  All
that's needed is a different metaphysics.
The questions about metaphysics are really attempts to breach the wall
that is built defensively around the standards of validation, and to
illustrate that "generalization" is not an objective thing.
Just came across this, last night:
  "One never *posseses* a metaphysical belief, but is possesed by it."
   -- C.G. Jung (in the "Answer to Job")
To the extent that one considers oneself free of metaphysics, one is
enslaved to it in ways that he doesn't recognize.
Does an instance of a hamburger sitting on a plate necessarily
generalize to "hamburger"?  to fattening processed food?  to fuel?  To
something that will answer the experience of hunger?  To something
that reminds one of a meal shared with a lover?
In theory, all these things, if they occur for someone somewhere,
might be reconcilable into one grand scheme, in which the various
metaphysics of observers are included in the description of the
system.  A "phenomenological relativity" as I call it.
(generalization of relativity)  This would perhaps have some claim to
objectivity, but would amusingly enough probably also lack generalized
formulation, in the sense folks mean when they claim that "f" means
the same thing to Newton as it does to Einstein.  Interpretation of
the formula would perhaps be an art, would include mystery, and would
involve direct experience.  And, this would require science to drive
itself as deeply as possible into metaphysics, rather than making
dispeptic grimaces and ignorant proclamations about the universality
of formula.
I'm thinking of my response about Mike Morris's proposed 'M' prophesy,
of a month or two ago.  What it might be like, etc.
>     Remember, too, that a hill is _never_ flat, by definition --
>a flat hill is a contradiction in terms.  So _if_ you have a hill
>(that is, if the existence of a hill is given), it can't be flat, 
>even if it's so short that the finest instruments can't measure
>its height; while if you decide that it _is_ flat, then you don't
>have a hill anymore.
Or, if you define a geometry which "flattens" hills, the geometry must
still preserve something that can be interpreted as "hillishnes", or
else admit to generalizing something that we experience (i.e. "hills")
out of existence.  Metaphysical considerations are quite empirically
real, for some of us.  But contemporary science apparently wants to
condition us to regard any parts of experience that concern
metaphysics as being irrelevant.  If you are making a map of telephone
connections, for example, it may be that you don't give a tinker's
cuss about where the hills are.  If you begin to rely only on the map,
you will never understand why the connections tend to go out in
certain areas when it rains.  But it may be that this sort of thing is
completely irrelevant to the process of mapping out the phone network.
One may be able to do without it.  He sniffs.  "Yeah, so what?  That
stuff is all irrelevant!  We don't need to know about 'hills' for what
we're doing."
The other side is saying, well, maybe, but what are you trying to do?
One ought to be trying to understand the particulars, as well, since
these are where our experience lives.  Grand generalization attempts
to blur all these, to arrive at universal concepts.  Well and good.  A
necessary process.  But it's only half of what Good Science would do.
It's really meaningless without the other half; one loses much of the
phenomena that are *worth* observing (because, perhaps, they bear on
what it means to "conceive").  What kinds of concepts are possible?
Where do they come from?  How much of Nature is conditioned by our
particular hardware?  This is especially worth asking when one
considers that one is attempting to explain the "circumference" to the
"center".  Can human "concepts" do that?  And if not, what do the
machines which we use to maniuplate the fragments of concepts that we
are capable of managing -- what do those machines accomplish?  (I'm
not saying it's nothing, I'm saying what is it?)
I'll probably regret having said this stuff.
-- 
"But among those whom this story reached were also the woman's in-laws,
 and they decided, without telling her a word, to find this angel and
 to see if he knew how to fly ..."

jayadams@is.dal.ca (Jason Elliot Adams) wrote:
>Jake Russell (jaker@u.washington.edu) wrote:
>: Ken Fischer  wrote in article ...
>: > Jake Russell (jaker@u.washington.edu) wrote:
>: > : Hello all Physics buffs!
>: > : I was wondering if someone could explain to me in terms of physics why
>: a
>: > : turbocharger draws less power from an engine than a supercharger does. 
>: The
>: > : turbo is driven by exhaust gasses, where a supercharger is driven by a
>: belt
>: > : directly off the engine.  Does it have something to do with exhaust gas
>: > : temperature difference across the turbo?
>: > 

>This isn't exactly what I think you're looking for but consider this...
>
>If something is attached to the engine crank it will use some of that
>crank's power to overcome internal friction and whatnot thus subtracting
>some of the power gains.  Whereas a turbo has no direct connection to the
>crank so it doesn't rob any of the power gain generated.
Pretty close, though I think that the turbo robs a bit of engine power by 
raising the backpressure at the exhaust ports.
Still, there is definitly energy being lost due to the uncontrolled 
pressure drop in the exhaust system.  If some of this pressure loss can 
be used to drive a turbo, you are already ahead (energywise) of a 
supercharger, which gets all of its power from the crankshaft.
George Lyle

-*--------
In article <55vpse$ub0@netnews.upenn.edu>,
Silke-Maria  Weineck  wrote:
> ...  As soon as it turns out, however, that some people who
> know intimately what they are talking about when talking about
> science share some of the concerns ...
??!!
What concerns did Derrida share with Heisenberg and Bohr?  
Russell
-- 
 The difference between life and a movie script is that the script has 
 to make sense.         -- Humphrey Bogart

In article <56026r$u0c@netnews.upenn.edu>, weinecks@mail1.sas.upenn.edu (Silke-Maria  Weineck) writes:
>meron@cars3.uchicago.edu wrote:
>: In article <55vnvu$940@netnews.upenn.edu>, weinecks@mail2.sas.upenn.edu (Silke-Maria  Weineck) writes:
>
>: >Just for clarification -- I "implied" no such thing. Centering is not 
>: >reducing by a long shot, and the "philosophy of physics" is not even 
>: >remotely at issue. At issue was the question whether "the Einsteinian 
>: >constant" provides a center in the sense which Derrida develops in SSP.
>: >
>: So, what is this Einsteinian constant they're talking about.
>
>Ask Richard, he has a theory about that; it's not the speed of light, as 
>far as I can gather. 
>
>But you know all about Einstein, Mati, don't you? Shouldn't your question 
>be, "what's a center?"
>
Perhaps I should.  But, I'll let it rest for the while and observe 
froma distance.  Would be easier if you guys could keep your posts to 
a sensible length and depth of inclusions (say, no more then a dozen 
or so) :-)
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

In article <5607jk$gnu@ssbunews.ih.lucent.com>, lew@ihgp167e.ih.att.com (-Mammel,L.H.) writes:
>In article <55vqa6$phh@news-central.tiac.net>,
>Richard Harter  wrote:
>>
>>
>>>... whereas Mati has never had a thought in his life.
>>
>>
>>Was this necessary?
>>
>
>Don't you get it? That's what he's claiming! He says we
>should ignore the opinions of Newton, Einstein, Weyl, Born,
>Mach, Maxwell, Minkowski, and whoever else you might
>care to name, because these are all just "thoughts" and
>"musings". He then LAYS DOWN THE LAW. Bah Dow! Bah Dow! Bah Dow!
>
>Mati brooks no thought of "thoughts" or "musings". He is the
>very caricature of the strait-jacketed scientific mind that
>the fuzzy-headed lame-brained Derrida-besotted pomo ninnys are
>trying to warn everybody about ... but pay no attention to them!
>What do they know! They're all involved in "thoughts" and "musings".
>
Neato.  I'll keep it for my collection.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

In article <328227EF.6685@cfer.ualberta.ca>, Paul Skoczylas
 wrote:
>  Marc-Etienne Vargenau wrote:
>  > 
>  > One of the problems with the US adopting the SI is that they do not
understand it
>  > and often break the rules. I visited the Petrified Forest National Park
People can't deal with change. Despite the fact that SI is so much
simpler, people are used to the archaic foot, mile, inch, blah, blah...
(Same with the language for that matter. English is one of the most
complicated, patternless languages, yet...)
Jeremy J. Olson... olson@ici.net
http://www.ici.net/cust_pages/olson/olson.html

In article <55vpse$ub0@netnews.upenn.edu>, weinecks@mail1.sas.upenn.edu (Silke-Maria  Weineck) writes:
>meron@cars3.uchicago.edu wrote:
>: In article <55vho0$o2k@netnews.upenn.edu>, weinecks@mail2.sas.upenn.edu (Silke-Maria  Weineck) writes:
>: >
>: >Quite. However, Derrida is in the business of thoughts, even though he 
>: >just might omit the just. Different priorities, so to speak.
>: >
>: Sure.  And the thoughts of scientists are sometimes interesting at 
>: their own right.  Still, it is worthwhile to realize that the thoughts 
>: of scientists, at any given moment, are a set which overlaps but is in 
>: no way identical to science.
>
>Believe me, I'm aware of it. I am not aware, however, of Derrida having 
>applied for a professorship in physics, so it doesn't seem all that 
>relevant. The argument against Derrida so far has usually taken the form, 
>"hah, the guy doesn't even know the science, he doesn't know what he's 
>talking about, why should I listen to him."
The argument as I've seen it (note that I'm not involved in it) was 
rather "His statements in the specific passage quoted don't seem to 
make any sense."
> As soon as it turns out, 
>however, that some people who know intimately what they are talking about 
>when talking about science share some of the concerns that seem oh-so 
>risible in the allegedly undereducated Derrida, 
I'm not sure what are the concerns you mention.  I'm yet to see a 
clear statement on this issue.
>the question of expertise is all of a sudden declared to be 
>irrelevant -- I find this an amazingly backtracking strategy.
Again, I'm not sure what expertise was declared irrelevant.  Sorry if 
I sound dense.
> If people who _do_ know QM or SR etc. as you seem 
>willing to grant draw philosophical conclusions that you don't agree 
>with, then you will have to address these conclusions in the realm in 
>which they were raised, and you cannot hide behind "you guys don't know 
>your science so I don't have to engage with your thought" anymore. I know 
>that Heisenberg and Bohr are controversial figures in the philosophy of 
>science and amongst scientists sans philosophy, but it seems that 
>dismissing them tout court will not do.
It is not an issue of dismissing, only of recognizing a very important 
distinction.  Let me limit the issue to physics, I'm not trying to 
speak for all of science here.  When you look at physics, at any given 
moment, you'll find a body of well defined statements, having to do 
with definitions of quantities, relations between them, how to measure 
them and how to compare them.  This part is the hard core of physics 
and here there is no room for arguments regarding interpretations.  
Given same initial conditions the equations will yield same results, 
regardless of whether the calculation is performed by a Nobel Laurate 
or by a graduate student.  OF course there is always the cutting edge, 
right at the boundary between the hard core and the unknown.  That's 
where things are just in the process of being defined, concepts are 
being generated and that's where the "great" ones leave their impact.
Now, around this hard core, there is a swirling "cloud" of personal 
philosophies and statements, where interpretations of "what does all 
this mean" appear and disappear.  It is no doubt quite fascinating but 
one should be aware that what one finds there are mostly personal 
statements, ones which don't necesserely represent physics, rather the 
beliefs of whoever uttered them.  Without this awareness it is easy to 
get such fallacies like one which appeared on sci.physics recently, 
when somebody claimed that science supports the concept of God since 
Einstein referred to God in various statements.
The difficult part, of course, is to recognize when reading somebody's 
statements which part is science and which just personal opinion.  
That's the point where knowing some science may be useful.
Mind you, non of this is any comment on Derrida's knowledge (or lack 
of) of science).  As I've mentioned above, I'm not involved in this 
argument and don't intend to.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

-Mammel,L.H. (lew@ihgp167e.ih.att.com) wrote:
]In article ,   wrote:
]>>
]>Possible.  If so, said philosophers should make the effort to acquint 
]>themself with all that happened in physics since the 20s, as well as 
]>not to put too much weigh in the words of the original contributors.  
]>The legacy of said contibutors is in the formalisms they left behind 
]>them, their thoughts on the subject are just this, thoughts.
]
]
]... whereas Mati has never had a thought in his life.
 I just had a thought. I know the good way for the American Telephone
 and Telegraph to cut their costs and boost share price a small,
 really tiny bit.
-- 
LAWFUL,adj. Compatible with the will of a judge having jurisdiction
                -- Ambrose Bierce, "The Devil's Dictionary"

In <327FA357.2302@warwick.net> Eric Kniffin 
writes: 
>
>jw wrote:
>> We already know that the
>> past can't be changed - because then the present
>> would be different - the question is *why*?
>
>Well, I don't know much of anything about the theory of relativity, or
>anything else dealing with this stuff.  I'm only going to comment on
the 
>observable results of all of this.
>As I see it, there are two possible answers:
>
>1-Time travel is not possible.  We don't have any evidence of any 
>time-travellers from our future.  And I don't believe that it could
ever be 
>kept in total secrecy.  I imagine that there will always be bad guys
who want 
>to come back and rule the world, and we'd know about them.
This explanation (macroscopic time travel is not possible)
covers all known facts - also fits
the relativity theory. I see nothing wrong with
this simple and elegant explanation. Do you?
>2-In answer to "We already know that the past can't be changed -
because then 
>the present would be different - the question is *why*?", we DON'T
know this 
>at all.  There was a science-fiction book called "Thrice Upon A Time",
where 
>a guy figured ot how to send information back a few minutes in time to
>himself.  Those who received that information acted on it, and changed
>everything from the moment they received the information onward.  They
talked 
>about what they called the "Superobserver", who existed outside of 
>time/space/reality.  The superobserver would see things happen.  Then
it 
>would see the information being sent back in time.  Then it would see
the new 
>reality forming from the moment that the informatin was received.  
But the superobserver's observation time was obviously *not* 
our physical time. It is misleading to speak of
both in the same terms... Yes, it *is* possible, 
even for us, to *observe* events in a different time sequence:
just videotape them, and then flash back and forth
watching the tape. This could create an *illusion*
of time travel. Similarly, your superobserver is experiencing
an illusion...
>This could be what is happening all the time for us.  We think that
Hitler 
>was a monster.  
Sure. And we are right, are not we? I mean: if we *do* think
that, we can't simultaneously think that we are wrong...
>But maybe something worse happened, people went back in time 
>to change it, and Hitler was the result.  
But if they went back - and *did* change it - then
it *never happened*; and if it never happened, then
these people had no reason to go back
and change it, and so did not! (Indeed, the *same*
people would not even *live* if the past had been
changed, because conception and chromosome
dance are such sensitive, delicate processes).
The "superobserver", therefore, 
observed what *never was*, experienced an
*illusion*, "virtual reality".
There is no problem with that. 
This interpretation covers all angles, even in
the science fiction scenario that you described.
>Maybe the "previous" problem was 
>so much worse that they didn't bother to go back and do away with
>Hitler.
So, your theory has it that our world is the *best
possible*, and *this* is why  no one goes
back in time - though they could - they
just don't want to spoil what's already optimal.
This would still make time travel impossible - but
it would be, according to you, a *moral* impossibility.
Your theory is that no being *physically* capable 
of time travel is *morally* capable of it; and so
it never happens.
I find this implausible, first, because
moral constraints are not so rigid; people would differ
in their estimates of what's the best past and 
the best present. But more importantly, there
remains the problem of "what if". Suppose a
certain experiment just never happens to be run, I 
*still* want the laws of nature to give me the answer to 
what would happen if it *was* run. And here we still run
into paradox with time travel: the effect would annihilate
its own cause and therefore itself. 
There are, however, two other ways to look at it, which I
rather like, which would both make what
*looks* like time travel possible.
 One cannot change one's own past -
because that change would negate itself.
But one can change the past's exact *replica*.
(1) Suppose that all that *can* happen
really *does* - all possibilities are realized.
(Why and how should the universe choose between
them?)  However, not all things that are possible
are *compossible*: it was possible for Hitler to
live *or* not to live - but not *both*.
So, for all possibilities to be realized,
the universe has to split, every split moment, into
many parallel universes, each of which realizes
one set of compossible events.
Then there would be no *logical* problem with "traveling" into
the *present* of a parallel universe - which is just *like* 
our past - and changing it. 
(2) The other possibility does not require
parallel universes. Suppose we could *re-create*
the past - make an exact replica of it, resurrect
all the people that lived then, put them in
exactly the same situations etc.
There is nothing logically impossible 
in this, and nothing that violates causality. 
But then one could change this resurrected "past",
and replay the events differently. 
In both (1) and (2), the "time travelers" are also
"superobservers" - they observe *both* time
sequences, the original and the revised. 
Both sequences are *real* - yet the time travel is illusory.

mkagalen@lynx.dac.neu.edu (Michael Kagalenko) writes:
>Jeff Inman (jti@isleta.santafe.edu) wrote:
>]mkagalen@lynx.dac.neu.edu (Michael Kagalenko) writes:
>]
>]> Metaphysics deals with the question of possibility of knowledge.
>]> Scientist does not need anything from metaphysics beyond the
>]> fact of possibility of knowledge, much like humans managed to do
>]> ad-hoc genetic engineering thousands of years before discovery of genes.
>]
>]If you don't understand the issue, just say so.  That would be the
>]scientific way to go.
>
> I understand the issue pretty well, humanities types are bothered
> to no end by apparent irrelevancy of their studies, and are 
> trying hard to latch onto science bandwagon. Heh heh.
Mati Meron's .sig goes like this:
 "When you argue with a fool,
  chances are he is doing just the same"
This seems to me to be a heuristic, rather than a scientific principle
directed from necessity, but I'll take it to heart.  The next step
will be to wonder whether, if I'm wise enough not to argue with a
fool, he will continue to argue with me anyhow.
>  jti:
>] The case is more clear if you go back, say, to Aristotle.
>
> Hand-picking cases to suit your theory ?
It is tempting to try and straighten foolishness like this out.
>] The accuracy of a prediction has nothing to do with its objectivity.  
>
> That would be the case if differing predictions are possible.
Not gonna do it.  Wouldn't be prudent.
-- 
"But among those whom this story reached were also the woman's in-laws,
 and they decided, without telling her a word, to find this angel and
 to see if he knew how to fly ..."

TJ  wrote:
>>Until I was 14 I thought people went to church to show off nice clothes
>> and see their friends and sing!)
It is, of course, to compare hats>
-- 
Alexander MacLennan  sandymac@sandymac.demon.co.uk

moggin@nando.net (moggin) writes:
> >     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.")
jti@isleta.santafe.edu (Jeff Inman)            
> Ring Lardner, I believe.  Haven't read it, tho.
     You're right.  I haven't, either.  But I guess that's clear.
-- moggin

In article <19961108232800.SAA03671@ladder01.news.aol.com>, lbsys@aol.com writes:
>Im Artikel , moggin@nando.net
>(moggin) schreibt:
>
>>:
>>
>>> >>Possible.  If so, said philosophers should make the effort to acquint
>
>>> >>themself with all that happened in physics since the 20s, as well as 
>>> >>not to put too much weigh in the words of the original contributors. 
>
>>> >>The legacy of said contibutors is in the formalisms they left behind 
>>> >>them, their thoughts on the subject are just this, thoughts.
>> 
>>lew@ihgp167e.ih.att.com (-Mammel,L.H.)
>>
>>> >... whereas Mati has never had a thought in his life.
>>
>>cri@tiac.net (Richard Harter)
>>
>>> Was this necessary?
>>
>>     Yes -- and relevant.  It's not a gratuitous insult, if you look
>>at what Mati is saying.
>>
>>-- moggin
>
>Wow, moggin on the warpath again. And once again it would help, if he
>knew, what that all was about. What Mati is saying (in response to an
>inconsiderate statement of Lew), is, that not everything single bit the
>old cracks ever uttered was of the same relevance as what they really left
>behind: the formulae. One could e.g. take Big E's everlasting "refusal" of
>the uncertainty principle: 'God doesn't play dice' he once expressed it.
>Of course he accepted it, but he really didn't like the noncausality.
>Today it is well accepted, that we don't know any better, that in the
>region of QM, nothing is either one or nil, but everything is only on a
>probability level. This is much too weird for our usual causal thinking,
>that anyone could claim, one had really dug it. It's *not* like saying: I
>arrive between 6 and 7 - probably, but it may be a bit later as well. It
>is like saying: Weather the sun rises tomorrow or not, we cannot say yet.
>Maybe - if we look to sharp at the earth - we may find it instead heading
>for Sirius. Something like that. So, if moggin had read just a fraction of
>what Mati has read from, on and about physicists and their mutterings, he
>would come to the very same conclusion - take it with a grain of salt,
>when the bigshots were rambling along. At least he claims, we should take
>Derridas exchange with Hippolyte with just that grain of salt, no?
>Pointing out that it happened as way back as the 60ies. Well, Lew cited
>from the 30ies or 40ies IIRC....
>
It is even more fun when we go further back.  One of the originators 
of the "least action" approach (an extraemly important part of physics 
but I won't get into details now), either Maupertois or Fermat (or 
maybe even both of them), was motivated in his work by theological 
notions.  So, if somebody reads his rambling on the subject and 
considers them to be part of the his contribution to physics, one may 
conclude something like "one of the centerpieces of physics is based 
on religious mistycism".  Which ain't true, although that founding 
father really thought so.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

In article , kfischer@iglou.com (Ken Fischer) wrote:
>        In General Relativity, freefalling objects move
> along geodesics in spacetime, and they move in inertial
> motion (are _NOT_ accelerated), but everybody says they
> are accelerated.
>        Bodies in orbit move in inertial motion, yet
> everybody says they are accelerated.
Relativists don't say they are accelerated.
>        The reason that I brought this up, is that the
> discussion was about binary stars (in orbit around
> each other) producing gravitational radiation because
> they are accelerating.
>        Gravitational radiation is supposedly a prediction
> of General Relativity.    In General Relativity, stars
> in orbit around each other are _NOT_ accelerated (in
> Newtonian gravitation they are).
>        So I am at a loss to understand how binary stars
> in orbit around each other produce gravitational radiation
> ( I must be a little stupid, maybe a lot :-), because
> someone said two people received a Nobel prize for
> their study of the effects of the gravitational radiation).
It's not a stupid question, your objections are quite natural.  Yet
gravitational radiation is consistent with general relativity and the
equivalence principle.
That there must be gravitational radiation of some sort is pretty
clear.  If you accelerate a charge, the stress-energy distribution of
space changes, so the curvature must change to reflect this.  This
manifests itself as a "wave" of curvature changes propagating
spherically outwards from the source. Because spacetime curvature can
possess energy density, these waves can carry energy away from the
system.
But the conditions for radiation are interesting.  The naive "it's
accelerating so it must radiate" condition is not sufficiently
precise.  It turns out that mere geodesic deviation is not sufficient.
Ohanian says that it is produced by a time-varying stress-energy
distribution, which makes sense from the above argument.  Yet
"time-varying" in GR automatically causes problems.  If you are in flat
spacetime, a particle moving at constant velocity will have a
time-varying stress-energy distribution from your point of view, but
will not, of course, from its own.  So that's not a precise
characterization of the conditions.  What you really need is a
gravitational quadrupole moment; that can't be transformed away using
the equivalence principle.
>        In Newtonian gravitation, a rock pushed off a cliff
> accelerates until it hits the ground below.   According
> to the definition of binary stars producing gravitational
> radiation, it would seem that a rock pushed off a cliff
> would produce gravitational radiation, at the speed of
> light, and a detector on the ground below should receive
> the gravitational radiation before the rock hits.
>        The nearness of the rock, even though it's mass
> is small, should produce a greater flux for the detection
> of gravitational radiation than binary stars many light
> years away.
Do the calculation.  If the flux is as strong as you think it is, then
why is everyone trying to detect astrophysical sources of gravitational
waves?
Look at box 36.2 of MTW.  They do a back-of-the-envelope calculation
that shows that the gravitational radiation flux of a meteorite
striking the Earth 10,000 km away is on the order of 10^-34 erg/cm^2,
whereas the flux received from a star exploding 100,000 light years
away is on the order of 10^-12 erg/cm^2.  That's a difference of 22
orders of magnitude!  (However, this is the total flux over a time
interval, and the flux for the latter case was calculated for a time
interval that is 10^12 times longer.  Still, that's 10 orders of
magnitude.)  But it's pretty clear that if you want the flux from a
rock to be on that order of magnitude, your detector is going to have
to be REALLY REALLY close to it.
And, of course, since the waves from the rock will be highly localized,
the relative intensities at different parts of the detector could be
quite significant if it's a large detector.  I think that things like
LIGO work better with approximately planar gravitational waves.
>        But in General Relativity, the falling rock is not
> accelerated, so it should _NOT_ produce gravitational
> radiation.    The question is, should binary stars in
> orbit produce gravitational radiation?
Yes.    Why do you keep trying to insist that a prediction of GR
isn't a prediction of GR?  If the calculation follows from the
equations of the theory, then it must be a valid prediction of the
theory, since the equations themselves were predicated on postulates
like the equivalence principle.  This is a "paradox" in the same sense
of the twin paradox -- something predicted by the equations that seems
not to make sense until you study it more carefully.
-- 
Nathan Urban | nurban@vt.edu | Undergrad {CS,Physics,Math} | Virginia Tech

I have posted two articles in sci.physics.relativity:
	Subject: A Physicist's Refutation of Autodynamics
	Subject: A Physicist's Opinion of Autodynamics
Please keep all discussion of them in sci.physics.relativity.
If you cannot find either article, please email me for a copy.
tjroberts@lucent.com

-*--------
In article ,
Gene C. Miller  wrote:
> Thus, a "surprise" in a fact about time can only mean that time 
> has failed to "behave" in a way that the regnant underlying 
> assumption of order had led physicists to expect. ...
Thus providing excellent opportunity for the practice of science.
Far from refutating, this corroborates the claim that puzzles,
that science does NOT depend on the "regnant underlying
assumptions" of concern, those constituting merely CURRENT
theory, and not serving in any fashion as a basis for science,
which proceeds along quite well (perhaps especially well) when
surprises show problems with those assumptions.  Indeed, if there
were no such surprises, there would be no need for science.  It
might be more true to say that science depends on the
inconsistencies in the universe than the consistencies!
Russell
-- 
 The difference between life and a movie script is that the script has 
 to make sense.         -- Humphrey Bogart

lbsys@aol.com wrote:
: Im Artikel <56026r$u0c@netnews.upenn.edu>, weinecks@mail1.sas.upenn.edu
: (Silke-Maria  Weineck) schreibt:
: >meron@cars3.uchicago.edu wrote:
: >: In article <55vnvu$940@netnews.upenn.edu>, weinecks@mail2.sas.upenn.edu
: >(Silke-Maria  Weineck) writes:
: >
: >: >Just for clarification -- I "implied" no such thing. Centering is not 
: >: >reducing by a long shot, and the "philosophy of physics" is not even 
: >: >remotely at issue. At issue was the question whether "the Einsteinian 
: >: >constant" provides a center in the sense which Derrida develops in
: SSP.
: >: >
: >: So, what is this Einsteinian constant they're talking about.
: >
: ...
: >But you know all about Einstein, Mati, don't you? Shouldn't your question
: >be, "what's a center?"
: >
: >S.
: As far as I've been following this, the word 'constant' in D.'s reply is
: not at all used in the sense a physicist or mathematic would understand it
: (as a given numerical value), nor is 'center' used in it's geometrical
: sense. Thus I don't think, that scientists will have an immediate
: understanding of this.
I agree wholeheartedly. And wouldn't you agree in turn that the point of 
asking questions can be to learn something one does not yet understand? 
The last question itself is a counter-example, obviously...
 My everlasting problem with philosophical texts is,
: that usually any new philosophocal school uses it's own jargon by
: redefining words, which do have a different meaning in the 'ordinary'
: understanding (as moggin probably would put it). Sciences do the same,
: from time to time, although once, it's done, it's used that way, ahem,
: generally ;-)...
It's a real problem; it's also necessary for certain operations; 
especially if a philosophy keeps building and wants to incorporate its 
earlier conclusions, suggestions, or ideas without having to keep providing 
the original lengthy argumentation; take the infamous phallogocentrism, 
or Heidegger's ontotheology (not that these are word with an 'ordinary 
understanding') --- there _are_ texts who explicate at length (and length 
it takes) how these terms are arrived at; if they are used thereafter 
without such an explanation, then by necessity. Same for science, 
obviously. There is the discovery of the gene, and then there is the term 
"gene" --- you wouldn't expect every text on genetics to explain what a 
gene is; if someone encounters the term without knowing it, the person 
would attempt to find someone or something to explain it to her instead 
of blaming the author of the text where it was encountered.
I'm not asserting that this analogy is valid beyond what limited use I'm 
giving it, btw.
But there are also terms that pose in themselves philosophical questions, 
that need to be interpreted in the process of being used: freedom, for 
instance (this, by contrast, is a "common term") --- no philosopher could 
talk about freedom in any prominent way without explicating which 
understanding of freedom he presupposes or develops.
Derrida, now, at times suggest that it is terms like "center" or "play" 
that need such re-interpretation.
A good polemical read on this is Hegel's, "Who Thinks Abstractly?"
Silke

OX-11 (jacob@omicron.csustan.edu) wrote:
: therre is an even more interesting fossil -- in the upper rio grands 
: valley of new mexico, there is the imprint of a bare human female footprint 
: in a sandstone outcropping that is around 10 -60 million years old. The 
: girl was walking and tripped. seh overcorrected by extending her foot and 
: made the imprint in the once soft mud of the riverbank.  It left a deep 
: impression clearly visible. You can even see the potho;e she stepped 
: into, and the splash marks extending out from it.....
: 
: 
Please explain in detail how it is possible to determine the sex of a
being from a single foot print.
Also please explain how you came to the conclusion about her acrobatics at
the time this foot print was made.  You speak as if you have video or film
of her preforming this act.
Peter THomas
-- 
Bearhugs & Footrubs
"I'll lose my beard when they shave it from my cold, dead face!"
Quote from the Razor's Anonymous Handbook
Peter Thomas is pst@csd.uwm.edu  B3/4 f+ t w- s r k+  (aka Freyr on IRC)
**************************************************************************
** FIGHT THE CDA!!  DON'T LET THEM TAKE AWAY YOUR FREEDOM OF EXPRESSION **
**************************************************************************

In article <55i7cr$h7q@coranto.ucs.mun.ca>, gpenney@nlnet.nf.ca (George Penney) wrote:
>   Now lets carry this to the limit!!.If we increse the acceleration
>    the radius of curvature will get smaller thus the beam will hit
>    the opposite wall further down.If we keep on increasing the accel-
>    eration the beam will eventualy hit the floor then move from right
>    to left across the floor and up the opposite wall toward the point
>    where it entered.With just the right amount of acceleration the
>    beam will again bend away from where it entered but this time it
>    will continue to loop in a circle forever not striking either wall!
Not with constant veritcal acceleration it won't.  How on earth did you
arrive at this conclusion?  It sort of seems that you think that the
path of the light beam is the arc of a circle, but I could be
mistaken.  In any case, there's no way to get it to walk up the same
wall from which it entered, not without mirrors or fiber optics or
something.  It "walks" across the floor because you're causing the
interception of its parabolic path to occur floor higher and higher up,
but it always has a velocity component going straight across the
elevator.  It can't turn around.
-- 
Nathan Urban | nurban@vt.edu | Undergrad {CS,Physics,Math} | Virginia Tech

In article , moggin@nando.net (moggin) writes:
>(Silke-Maria  Weineck):
>> 
>> : >Just for clarification -- I "implied" no such thing. Centering is not 
>> : >reducing by a long shot, and the "philosophy of physics" is not even 
>> : >remotely at issue. At issue was the question whether "the Einsteinian 
>> : >constant" provides a center in the sense which Derrida develops in SSP.
>
>meron@cars3.uchicago.edu (Mati):
>
>> : So, what is this Einsteinian constant they're talking about.
>
>Silke:
>
>> Ask Richard, he has a theory about that; it's not the speed of light, as 
>> far as I can gather. 
>
>     That much is definite (I'm willing to declare).  What it _is_,
>is harder to say -- my vote (uninformed by any substantial knowledge 
>of physics) is going to the lack of absolute space and time.  (More
>on the whole business in my reply to Hardy.  Yes, Mati, you're right: 
>"Einsteinian constant" _would_ be the wrong term -- on my reading, 
>that's what Derrida is pointing out to Hyppolite.)
>
OK, I'll buy that much.  It seems that at the moment it is more clear 
what it isn't then what it is, but I don't feel qualified to guess at 
what is meant there, yet.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"

In <55vo06$a7q@dfw-ixnews9.ix.netcom.com>
   dcoll@ix.netcom.com(Daniel E. Collins) writes:
>Well, I can't say the above paragraph is correct or not.  I don't know
>what you are saying.  If the first guy is saying that there is *NO*
>loss of power via the use of a turbo, then he is partly wrong.  Of
>course there is *some* power loss due to the use of a turbo, it takes
>some energy to turn the turbine.  If you are saying that the operation
>of a turbo has nothing to do with the temperature of the exhaust
>gasses, then you are partly wrong.  The real question is how much power
>is used to generate the boost for either a turbo or a supercharger. 
[Technically speaking, a turbo-charger is actually a turbo-supercharger,
differntiating it from a mechanically-driven one.]
Most of the power used by the turbocharger is usually discarded in
other engines. The energy comes from the residual pressure in the
exhaust gases, and their very high temperature. The turbine converts
some of this power by directing the exhaust gases onto turbine blades
which are mechanically linked to compressor blades blowing air on the
"fresh air" side. [A bit of a digression:  turbo's aren't positive
displacement so they don't actually increase pressure (i.e. compress),
they just blow harder. The pressure increase is seen when the
accelerated air is trapped - more molecules in the same space means
higher pressure.]
Engines not fitted with turbochargers can be fitted with "extractor"
exhaust manifolds which use some of the energy in the exhaust gases
to improve exhaust flow. An extractor exhaust with a turbocharger
will probably have too little energy left to make boost.
I hope that makes things a little clearer.
>Actually, I can't understand why some love turbos and hate 'chargers or
>vice versa.  I think they are both kinda cool.
Well I thought they were HOT!  How much you want to bet that I'm right? :-)
-- 
Bernd Felsche {speaking for himself}
MetaPro Systems Pty Ltd, 130 Fauntleroy Avenue,
Redcliffe, Western Australia 6104
Phone: +61 9 479 3722    Fax: +61 9 479 3720

> > For example, I would be forced to respond to his ph.D. with
> > 
> > Anthony Potts, B.A. (Hons, Oxon.) M.Phil, GradInstP.
Let's just all start adding our entire resumes to our signatures.
oddly,
doc rogers
owner, ringmaster, chief expeditor
Ox In Sox, Inc.
http://home.sprynet.com/sprynet/docrog
"Why the hell does everyone insist on putting some stupid quote at the end
of their post? It's really fucking annoying!"
                                                ------------ doc rogers

Don Dale (dale@princeton.edu) wrote:
: Two hundred years ago, we thought that there was a fundamental limit to
: travel speeds because even the fastest horses couldn't go over 30 mph, no
: matter how well they were bred, trained or jockeyed.
And with the advent of faster transportation, there were learned and
highly degreed scientists who spouted all sorts of scientific reasons
why we would never exceed the speed of sound, and so on.
The history of scientific "can't"'s is a long series of embarrassing
statements by damn fools.
Fortunately, we move along in spite of them.
--
Tony
Taint Anthony the Astonished                BAAWA!
http://world.std.com/~apl
Surgeon General's Warning: Quitting Religion Now Greatly Increases
the Chances of World Peace.

Don Dale (dale@princeton.edu) wrote:
: Two hundred years ago, we thought that there was a fundamental limit to
: travel speeds because even the fastest horses couldn't go over 30 mph, no
: matter how well they were bred, trained or jockeyed.
And with the advent of faster transportation, there were learned and
highly degreed scientists who spouted all sorts of scientific reasons
why we would never exceed the speed of sound, and so on.
The history of scientific "can't"'s is a long series of embarrassing
statements by damn fools.
Fortunately, we move along in spite of them.
--
Tony
Taint Anthony the Astonished                BAAWA!
http://world.std.com/~apl
Surgeon General's Warning: Quitting Religion Now Greatly Increases
the Chances of World Peace.

In article <55vn7s$38g@panix2.panix.com>, G*rd*n <+@+.+> wrote:
>
>I wonder if people's notions of time have not been
>increasingly spatialized, regularized, and mechanized in the
>modern era.  Because of capitalism, of course.  Has anyone
>written about this?  ................
There was a book out a few years ago which expanded on just this
topic. As I recall, it was viewed to be so resolutely "anti-time"
that it was thought to be a little weird. Didn't read it, though.
Lew Mammel, Jr.

In article <3277b8e6.2502947@news.mclink.it>,
Stefano Bianchi  wrote:
>Hi all.
>I'm just a student of Physics, so I should learn a lot of things
>before even asking something like that, but I was wondering how
>tachyons could travel faster than light ( and it should be by
>definition ), while, as far as I know, this shouldn't be possible.
>Thanks a lot, Stefano
What special relativity forbids, exactly, is any particle which is
travelling at less than the speed of light being accelerated to a
speed greater than the speed of light, or for that matter one that is
travelling faster than the speed of light from being decelerated to a
speed less than that of light.  In both cases the reason for the 
prohibition is that an infinite amount of energy would be needed to
accomplish the change in speed.  There is nothing especially wrong about a
particle that always travels faster than light.
There are some peculiar properties of the tachyons, however.  Their mass
would have to be pure imaginary and their energy goes down instead of up
as their velocity increases, reaching zero at infinite velocity.  There
can be additional problems with tachyons in Quantum Field Theories.
Tachyons have been searched for experimentally and not found.
-- 
 \ _____ /             Maurice Barnhill, mvb@udel.edu                 /\___/\
  |_____|           http://www.physics.udel.edu/~barnhill/           ( O   O )
 /       \  Physics Dept., University of Delaware, Newark, DE 19716  (___V___)

In article <32834706.1BD1@eskimo.com> Stephen La Joie  writes:
>Bill Oertell wrote:
>> 
>> 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?
>> 
>>     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
>Humm. If you know the open circuit voltage to be 12 volts, and the voltage 
>falls to 9 Volts at 500 Amps, why can't you calculate the Theivenin 
>resistance?
Internal resistance for a lead-acid car battery in good condition is about 
0.003 ohm.
                               Bob

Hardy Hulley :
>>>>>>>>The question of what does quantum physics *really* mean,
>>>>>>>>physically, is still very controversial, and I guess one could adopt the
>>>>>>>>stance that it isn't meaningful. Of course, you'd then have to contend
>>>>>>>>with the fact that it does make incredibly good *testable* predictions,
>>>>>>>>in contradistinction to Derrida, who makes no testable claims at all.
Anton Hutticher :
>>>>>>>And successful predictions are of course the only reliable way to 
>>>>>>>distinguish complex statements which sound like gibberish, but are not,
>>>>>>>from complex statements which are gibberish. The exception are fields
>>>>>>>which are formalized enough to permit a formal analysis without recourse
>>>>>>>to verbal handwaving. 
moggin@nando.net (moggin):
>>>>>>     Thanks, folks, for falsifying Russell's statement that logical
>>>>>>positivism is dead.
zeleny@oak.math.ucla.edu (Michael Zeleny):
>>>>>Would you care to explain what you imagine the views suggested above
>>>>>have to do with logical positivism?  Or are you merely trying to show
>>>>>incompetence in yet another discipline?
moggin@nando.net (moggin) writes:
>>>>     You're in no position to be issuing challenges, but I'll humor
>>>>you, just this once.  Logical positivism:  meaning is verification;
>>>>a statement that can't be verified is meaningless.  
zeleny@oak.math.ucla.edu (Michael Zeleny):
>>>Not.  Verificationism is neither necessary nor sufficient as a
>>>characterization of logical positivism.  For starters, you must
>>>do justice to the genus and the differentia.
moggin@nando.net (moggin) writes:
>>     So who's characterizing?  I offered a tenet, namely the one
>>in common with the statements above.
zeleny@oak.math.ucla.edu (Michael Zeleny):
> In other words, your offering had nothing to do with falsifying the
> statement that logical positivism is dead.  Thank you for playing.
     Sure it did: if a central tenet of logical positivism is in
circulation, and cited with approval, then it must not be dead.
-- moggin

In article <560kd6$aip@lynx.dac.neu.edu>,
Michael Kagalenko  wrote:
>
> I just had a thought. I know the good way for the American Telephone
> and Telegraph to cut their costs and boost share price a small,
> really tiny bit.
This thought is a little late.
Lew Mammel, Jr.

Silke-Maria  Weineck  wrote:
> > ...  As soon as it turns out, however, that some people who
> > know intimately what they are talking about when talking about
> > science share some of the concerns ...
turpin@cs.utexas.edu (Russell Turpin)
> ??!!
> What concerns did Derrida share with Heisenberg and Bohr?  
     Oh, boy -- does Silke have a book for you!  (Actually,
she's mentioned it before.  If you'd read it, you'd already
know the answer.)
-- moggin

In article <560tn7$a5s@rocky.scvnet.com>,   wrote:
>hatunen@netcom.com (DaveHatunen) wrote:
[...]
>It's good that you recognized that teaching was not your "cup of tea."  
>Many people have made that determination after they were already stuck in 
>the profession, to the detriment of both themselves and their students. 
You seem to have read what I wrote with glasses of your preferred
color. Teaching was my "cup of tea". I was acclaimed by my students for
it. It was being a public school teacher that wasn't my "cup of tea".
In fact, I continued to substitute teach for a number of years
thereafter.
-- 
    ********** DAVE HATUNEN (hatunen@netcom.com) **********
    *               Daly City California                  *
    *   Between San Francisco and South San Francisco     *
    *******************************************************

meron@cars3.uchicago.edu (Mati):
> [...] One of the originators 
> of the "least action" approach (an extraemly important part of physics 
> but I won't get into details now), either Maupertois or Fermat (or 
> maybe even both of them), was motivated in his work by theological 
> notions.  So, if somebody reads his rambling on the subject and 
> considers them to be part of the his contribution to physics, one may 
> conclude something like "one of the centerpieces of physics is based 
> on religious mistycism".  Which ain't true, although that founding 
> father really thought so.
     Well, _one_ of them is -- as I've mentioned before, Newton
imported his concept of action-at-a-distance to physics from his
studies in hermetic philosophy (read: religious mysticism).  The
reaction from his colleagues was just what you would expect: they
felt it was poppycock.  But when the dust settled (as one might
say), it had become orthodoxy, and it stayed that way for several
hundred years.
-- moggin

Ken Fischer wrote:
> 
> kkostenb (kkostenb@ccs.carleton.ca) wrote:
> : I'm having trouble finding out how many litres of gasoline
> : fit into one cubic metre (or gallons/cu feet). I'd need the information,
> : but no little physics. Do you know the answer?
> 
>          Sounds like a trick question, forget gallons and
> cubic feet.
>          Isn't one cc and one ml the same no mater what
> the liquid?     My goodness, 100 x 100 x 100 / 1000?
> 
> Ken Fischer
Unfortunately, a milliliter (mL) is defined as cubic CENTImeter
one litre is a cubic decimeter, which is one thousandth of a liter
deci = 1/10 m, therefore 10x10x10 = 1000
volume is volume.  Your hangup might be that 1mg is defined as 1ml of
water at 4 (or thereabouts) degrees Celsius, therefore the weight to
volume measure doesn't hold
Later
Mark Schaefer

In article , apl@world.std.com (Tony Lawrence) writes:
>Don Dale (dale@princeton.edu) wrote:
>
>: Two hundred years ago, we thought that there was a fundamental limit to
>: travel speeds because even the fastest horses couldn't go over 30 mph, no
>: matter how well they were bred, trained or jockeyed.
>
>And with the advent of faster transportation, there were learned and
>highly degreed scientists who spouted all sorts of scientific reasons
>why we would never exceed the speed of sound, and so on.
>
Nonsense never dies, apparently.  The speed of sound was never a speed 
limit in science and instances of objects moving faster then the speed 
of sound (bullets and artillery shells) for example, were well known 
and documented.  The issues with speed of sound were purely 
technological, not scientific.
>The history of scientific "can't"'s is a long series of embarrassing
>statements by damn fools.
Yes, though in a slightly different meaning than the one you intended.
Mati Meron			| "When you argue with a fool,
meron@cars.uchicago.edu		|  chances are he is doing just the same"