Subject: Re: Would a kinetic energy weapon leave residual radiation?
From: jac@ibms46.scri.fsu.edu (Jim Carr)
Date: 11 Jan 1997 16:24:59 GMT
meron@cars3.uchicago.edu wrote:
}
} The energy isn't really high enough for the creation of particles.
} Given center of mass corrections etc. you need /gamma of 5-6 or so,
} meaning v/c around 0.98 or higher.
bfielder@quadrant.net writes:
>
>True enough, I stand corrected.
Not true enough; stand un-corrected.
A minor fact: a 600 MeV proton, which has a gamma less than 2, will
happily produce pions when striking a graphite target. Reverse the
kinematics and the same thing will happen.
Pion "factories" at TRIUMF and PSI (fka SIN) run at that energy,
while the one at LAMPF ran at 800 MeV, giving access to higher
energy pions for some experiments. Rates (and the threshold)
depend on target mass (to get the center-of-momentum energy)
but 1 GeV protons are over the pion threshold for any target.
Mati must be thinking of making anti-protons.
--
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.
Subject: Re: Can a Black Hole have a Charge?
From: Erik Max Francis
Date: Thu, 16 Jan 1997 15:08:12 -0800
John Jordano wrote:
>
> Given the condition that an excess of positively charged particles were
> to fall into a black hole, would the black whole exhibit a positive
> charge?
Yes. Black holes in fact have only three salient characteristics outside
of the horizon: mass, charge, and angular momentum. This is the so-called
"no hair" theory. Note that baryon number is not included, so, for
instance, the only difference between a hole made out of protons and one
made out of antiprotons is the charge.
Charged holes will tend to neutralize themselves very quickly; the
electromagnetic interaction is many orders of magnitude stronger than the
gravitational interaction, so oppositely-charged particles will tend to be
drawn in quickly to a hole with substantial charge while similarly-charged
particles will be driven away; in the end you have negative feedback and
the hole tends to become more neutral.
> My intuition says "Yes," but if so, how does the "information" about the
> charge inside of the event horizon get communicated outside of the
> horizon? It's my understanding that the effect of a charge is carried
> by the electromagnetic force, and that the force carrying particle for
> the EM force are photons. If photons can't escape from a black hole,
> then how can the black hole exhibit the positive charge?
This is a common question which is answered in several FAQs; check the
sci.physics FAQ. The short answer is that the mediating particles are
virtual, and thus are not restricted to all the limits that real particles
are (such as having positive momentum and travelling no faster than c). If
you think about it, this makes sense; if you take the particle interactions
as little billiard balls that fly around, then all interactions would be
repulsive, and they're clearly not. Virtual particles can "cheat."
> Similarly, how does a black hole exhibit gravity? If you take for
> granted that a black hole exhibits gravity (one of it's defining
> features), then how does the force of gravity get transmitted? We don't
> have any evidence to support it, but let's assume for a moment there are
> force carrying particles for gravity, as there are for other three
> forces, and let's call them gravitons.
As you imply, gravitons are not part of any formal theory of quantum
gravity, so talking about them in your explanation might be premature.
In the classical limit, the gravitational field is "left behind" as
progenitor collapses to form a black hole. The spacetime curvature around
a black hole is static and thus there's no need for anything to "get out of
the hole" to exhibit gravitaton.
> For gravity to be exhibited by
> the black hole, gravitons must be emitted by the black hole. The
> definition of the event horizon of a black hole, however, is that
> nothing can ever leave.
As above, if you go the route of using gravitons to explain mediation, then
you come to the same answer, because those interaction-mediating gravitons
are virtual.
--
Erik Max Francis | max@alcyone.com
Alcyone Systems | http://www.alcyone.com/max/
San Jose, California | 37 20 07 N 121 53 38 W
&tSftDotIotE; | R^4: the 4th R is respect
"You must surely know if man made heaven | Then man made hell"
Subject: Re: Gravity a property of Energy, too?
From: Erik Max Francis
Date: Thu, 16 Jan 1997 15:32:26 -0800
steveb@tds.bt.co.uk wrote:
> If mass is considered as "condensed energy" does this imply that
> sufficient energy would exhibit a gravity field?
Yes. In general relativity the generator of gravity is the stress-energy
tensor, which, as the name implies, involves energy. For most ordinary
circumstances, mass is by far the largest contributor to this tensor, and
thus that's noe of the reasons that Newtonian gravitation is a
correspondence theory to general relativity.
> Or: if I had a battery that happend to contain the same electrical
> energy as is held in the mass of a planet, would there be a gravity field
> about the battery??
Yes.
--
Erik Max Francis | max@alcyone.com
Alcyone Systems | http://www.alcyone.com/max/
San Jose, California | 37 20 07 N 121 53 38 W
&tSftDotIotE; | R^4: the 4th R is respect
"You must surely know if man made heaven | Then man made hell"
Subject: Re: PH.D.s are useless
From: lbsys@aol.com
Date: 17 Jan 1997 10:50:27 GMT
Im Artikel , meron@cars3.uchicago.edu
schreibt:
>Teller committed the unspeakable horror of insisting that "He who
>wants peace should prepare for war" thus making him the favorite
>whipping boy of wishful thinkers around the world :-)
C'mon, Mati, you know more about it ;-). Teller did not only invent the
Super (I mean the feasable one, no one could have thrown a supercooled
device from a B52 :-), which is bad for itself (would you work for the
national weapons program?), but also is a well known right winger, who
pleaded for using the bomb on the commies and in his later years was all
for star wars (which really makes him look more stupid than ever: with his
brains he should have seen the non-feasability of the project, but
politics was dearer to him then). The difference to people like Pol Pot is
a) he personally would not have done any harm to people, he rather belongs
to the class of 'I-only-pushed-the-button'.. and b) he didn't had the
chance to be of harm to people. Maybe he would have considered not to push
the button then, who knows.... But he left no doubt, that he meant to.
>As for Pol Pot, we're talking about real horrors. Check out "Khmer
>Rouge", in Cambodia.
The most dangerous untruths are truths slightly deformed.
Lichtenberg, Sudelbuecher
__________________________________
Lorenz Borsche
Per the FCA: this eMail adress is not to
be added to any commercial mailing list.
Uncalled for eMail maybe treated as public.
Subject: Re: Astrology: statistically proven now!
From: lbsys@aol.com
Date: 17 Jan 1997 10:50:29 GMT
Im Artikel ,
mmcirvin@world.std.com (Matt McIrvin) schreibt:
>> Most combinations showed no aberrations outside
>> noise level, but some did to a high degree. One
>> example given was, that 2735 "taurus" man should
>> have married "fish" woman, and a value of 2680 or
>> 2790 would have been accepted as noise, but the
>> real value of 2540 remained absolutely unexplained.
>
>I get a probability of about 1 in 5000 that there would be
>an anticorrelation at least that strong for this combination
>as a result of chance.
>
>On the other hand, the probability of getting a chance
>anticorrelation *or* a chance correlation this strong for
>*any one* of the 144 combinations is about 1 in 36, if
>my calculations are correct.
That' the interesting part. Indeed if it was only one of the 144...
> That's not so much
>overwhelming as somewhat unusual and possibly
>suggestive (whether of a real effect or of some sort of
>bias, I don't know).
Yes
>Of course, they apparently got more than one significant
>result, so that would correspondingly decrease the probability.
Exactly. As I understood they had about a dozen correlations over
significance level. And then there was the run with those constructed
virtual starsign giving nothing but statistical random noise.....
>If the result was statistically improbable but not *terribly* improbable,
>it's not inconceivable that they could get an effect for the actual
>star signs but not for the controls, simply by chance.
Yes, that also is true.
>Since the study didn't involve any of the more complicated astrological
>indicators, such as what planet was in what house when, it could just
>have uncovered something completely unrelated to astrology, such as a
>relation between personality type and the season experienced in
>infancy.
Very much so and they did not claim anything else.
>But in the absence of a proposed mechanism to test, the best
>thing we can do, I suppose, is to look for replication of the result.
Yes indeed. Although I'm eagerly waiting for the study being published in
real. I'll let you know, when I got it.
Cheerio
The most dangerous untruths are truths slightly deformed.
Lichtenberg, Sudelbuecher
__________________________________
Lorenz Borsche
Per the FCA: this eMail adress is not to
be added to any commercial mailing list.
Uncalled for eMail maybe treated as public.
Subject: Re: c constant? another try
From: Jan Pavek
Date: Fri, 17 Jan 1997 11:50:20 +0100
Ok! No comments. That means that everyone agrees with me.
The nearer to the center of a mass you get a higher energy amount and
the speed of light and time increases.
But then, could there be made an exact Hubble constant?
Jan Pavek wrote:
>
> Hi! I know that I don't know much but I want to understand, to learn.
> So please tell if my thoughts are mad, stupid, crazy, stunning,
> fascinating, amazing or just a pit of rubbish. Please be honest. Thanks!
>
> > I don't get a redshift for the assumption lightspeed being constant.
> > With time depending on energy it also depends on mass and so you get
> > first for more massy object a blue shift and then the red shift when the
> > mass is moving away what makes a shift to anywhere. But if c would
> > depend on the local energy amount so on the mass there would be no such
> > blue shift. What am I doing wrong?
> >
>
> Jan
>
> ---
> I know I'm not a brainy one, but I'm working on it!
> I only want to understand.
>
> Jan Pavek \|\*(:-)
> mailto:p7003ke@hpmail.lrz-muenchen.de
> surfto: http://www.lrz-muenchen.de/~gravilabs
> "Why don't we see it as it is? A flower, a tree, a mountain, a bee ..."
> "Do you realize the power of the dream?..."
--
Jan
---
I know I'm not a brainy one, but I'm working on it!
I only want to understand!
Jan Pavek \|\*(:-)
mailto:p7003ke@hpmail.lrz-muenchen.de
surfto: http://www.lrz-muenchen.de/~gravilabs
"Why don't we see it as it is? A flower, a tree, a mountain, a bee ..."
"Do you realize the power of the dream?..."
Subject: Re: strength of hemp fibers
From: "Achim Recktenwald, PhD"
Date: Fri, 17 Jan 1997 08:04:44 -0500
Alan "Uncle Al" Schwartz wrote:
[snip]
>
> >>Marijuana is utterly harmless, which is why it is so dangerous. A quick
> >>recombinant DNA knockout will control or end its cannabinoid synthesis.
> >
> >Is it really that simple?
>
> It has already been done. The genetic mechanism of cellulose fiber
> determination is also in hand. One could design a Douglas Fir or a
> cotton plant to spec - BUT IT WOULD BE WRONG!
>
> > Could it be made noticably different from a
> >narcotic version? If so, that's a great subject for research. Sure, >the hemp farmers will initially lose some product due to hippies raiding >the fields, but that shouldn't last long after they find out it's >useless for their purposes.
>
> Natural hemp is about 0.2 wt-% THC. British Columbia is hydroponically
> growing 30 wt-% THC flowerheads. One needn't change anything, only grow
> the original plant - BUT IT WOULD BE WRONG!
The weekly German news-journal 'Der Spiegel' reported in one issue
during the last month that hemp-farming is a very interesting and
growing market in Europe. The strains used have almost no marijuana at
all, so that the 'value' is purely agricultural.
From that report and some other sources I would like to say that your
'BUT IT WOULD BE WRONG!' is a special situation in the US, where every
president or every other one has to start a 'War on Drugs' with the
Pentagon at the fore-front. (I am against the consumption of drugs, but
think this militaristic strategy is silly and futile.)
The politicians in Europe do and did not seem to mind; if I remember
correctly, the initial re-invention of hemp-farming and the development
of special machinery was even subsidized by the European Union and the
member states.
Achim
Subject: Re: Why can't 1/0 be defined???
From: ags@seaman.cc.purdue.edu (Dave Seaman)
Date: 17 Jan 1997 09:33:32 -0500
In article ,
Travis Kidd wrote:
>ags@seaman.cc.purdue.edu (Dave Seaman) writes:
>>One nit. The expression 0^0 does indeed have a value, which has
>>nothing to do with limits. This is discusses in the sci.math FAQ,
>>which gives several reasons why 0^0 = 1, at least in the case where the
>>exponent is considered to be an integer.
>You cannot give reasons in mathematics, except for reasons why (actually
>how) we know something to be true. 0^0 is indeterminate--possibly on
>all the reals, possibly only between 0 and 1.
The adjective "indeterminate" applies only to limit expressions. I was
not discussing a limit expression. Since 0^0 = 1 is a theorem of ZF
and can be found in textbooks on axiomatic set theory, I consider that
to be a reason for saying that 0^0 = 1 just as surely as 2 + 2 + 4, as
long as you are talking about arithmetic on the natural numbers.
>>My favorite reason: 0^0 is the cardinality of the class of functions
>>mapping the empty set to itself, which is one.
>That's certainly one of the uses of 0^0. But not the only one.
Another "use" of 0^0 lies in the fact that if x is an element of any
monoid G, then x^0 = the identity element of G. The exponent 0 in this
case is the natural number 0. Since the real numbers are a monoid, it
follows that 0^0 = 1, where the first zero is a real number, the second
zero is a natural number, and the result is a real.
--
Dave Seaman dseaman@purdue.edu
++++ stop the execution of Mumia Abu-Jamal ++++
++++ if you agree copy these lines to your sig ++++
++++ see http://www.xs4all.nl/~tank/spg-l/sigaction.htm ++++
Subject: Re: Speed of Light
From: David Kastrup
Date: 17 Jan 1997 13:36:26 +0100
vit writes:
> > speed travel. The gist of the article included a computer program that
> > showed what objects would look like at various speeds.
> >
> > The most interesting aspect to me professionally was the observation of
> > electrical circuit response at those speeds. For instance at about .75c
> > computer response of electronic equipment would become prohibitively sl=
ow
> > for connections in access of 300ft. Based on your discussion I think th=
is
> > Conflicts to one of your opinions but I'm not sure.
> >
> -snip-
> I don't think the article you read was a very serious one. As stated in
> the postulats of theory of relativity, there's no way to distinguish
> between any two inertial systems. If the computer is not moving with
> respect to an inertial frame of refference, it has to perform the same
> as on Earth or anywhere else. No slowing down or whatever.
Well, viewed from outside, the computer would have serious problems
reacting to something approaching it because the info would run slowly
through the wires to the front.
Viewed from inside, the problem stays the same, just looks different.
From the inside it looks as
a) the approaching thing is indeed much nearer than from viewed
outside, so we have less time to react to it
b) the light from the approaching thing is not much faster than the
thing itself, so we have even less time to react (if we consider the
speed with which the *information* reaching us about the approach
increases, it can be definitely *more* than the speed of light, even
viewed from inside).
While the internals on this ship will work perfectly normally, the
interaction with the outside could be rather unfriendly, so to speak.
Relativistic effects make intergalactic speeding even more dangerous
than it would be anyway.
--
David Kastrup Phone: +49-234-700-5570
Email: dak@neuroinformatik.ruhr-uni-bochum.de Fax: +49-234-709-4209
Institut f=FCr Neuroinformatik, Universit=E4tsstr. 150, 44780 Bochum, Germa=
ny
Subject: Re: Thought Experiment
From: Joseph Mark Inman
Date: Thu, 16 Jan 1997 05:09:51 -0800
crjclark wrote:
>
>(snip)
> Atonal music may in fact not resonante much in a consonant manner.
> With all of the dissonant irregular beats there will be much
> noise. But if there are two tones, (fundamental or harmonics),
> sounded in common, there will be resonance.
YOU HAVE NO CONCEPT OF WHAT ATONALITY IS!!!
Atonality is totaly seprate from consonance and dissonance. To have an atonal piece the
only thing that has to go on is a lack of a tonal center. You can do this with all major
and minor chords, and the chords relative each other would create a more "consonant
sound" than say a tonal peice such as an early Romantic piece that uses 9ths and +6ths
chords (Beethoven- Eroica). So your "fact" that atonal music doesn't resonate much in a
consonant manner is a bunch of BS (Put on your Boots, because we're walking in it!)
> > In fact, do these two things in this order:
> > (1) Explain what 'precision language' means to you.
>
> I have no idea what 'precision language' is.
don't you really mean to say, "I have no idea what 'atonality' is"??
>(snip)
>
> Craig Clark
In addition- I don't think you have much of a concept of tonality either. Oliver
Messian (I probably spelled his name incorectly, so don't go saying whatever) had
written several *TONAL* (because they had a *TONAL CENTER*) pieces in addition to his
*ATONAL* (because they DIDN'T have a *TONAL CENTER*) that were just as dissonant (or
consonant, depending on how you look at it) as the most of his pieces. This is because
he would use a poly-modal aproach in some of his peices, where say the Tonal center was
C, he would have the consonant chord spelled C E Eb G, or something like that, and the
"disonant, or leading chord" be some form of V (or G).
J. Mark Inman
Subject: Re: "What causes inertia?
From: jac@ibms46.scri.fsu.edu (Jim Carr)
Date: 12 Jan 1997 03:24:25 GMT
Jim Carr wrote:
|
| | Is this a reference to the reanalysis by Fishbach (? at Purdue)
| | that led to the fifth force brouhaha? If so, it went away with
| | more precise modern tests of that hypothesis.
|
| glird@gnn.com () writes:
| > No! "closer examination" was restricted to Aetvos's data, which
| >did NOT support the equivalence hypothesis.
|
| This last statement does not imply a "no" answer, because the
| Fishback PRL contained only an analysis of the Eotvos data,
| not any new data. New data came later.
glird@gnn.com () writes:
>
> The "new data (uncited)
The work by Eric Adelberger's group, for example.
>might have done away with a non-existant
>"fifth force" but probably didn't change Aetvos's results which
>show that inertial versus gravitational force are NOT equivalent.
Nothing can change the Eotvos data, but new experiments can shed
light on whether the quoted errors were unrealistically small or
whether there were systematic errors that caused the differences.
Fishbach pointed out the discrepancy, with a particular proposed
explanation, and new experiments were done.
There is also an continuing experiment using the reflectors on the
moon to study its orbit in detail, and a recent Physics Today news
article stated that the results are consistent with the equivalence
principle. You might want to track that down if you are interested.
--
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.
Subject: Re: Thought Experiment
From: Joseph Mark Inman
Date: Thu, 16 Jan 1997 05:09:23 -0800
crjclark wrote:
>
>(snip)
> Atonal music may in fact not resonante much in a consonant manner.
> With all of the dissonant irregular beats there will be much
> noise. But if there are two tones, (fundamental or harmonics),
> sounded in common, there will be resonance.
YOU HAVE NO CONCEPT OF WHAT ATONALITY IS!!!
Atonality is totaly seprate from consonance and dissonance. To have an atonal piece the
only thing that has to go on is a lack of a tonal center. You can do this with all major
and minor chords, and the chords relative each other would create a more "consonant
sound" than say a tonal peice such as an early Romantic piece that uses 9ths and +6ths
chords (Beethoven- Eroica). So your "fact" that atonal music doesn't resonate much in a
consonant manner is a bunch of BS (Put on your Boots, because we're walking in it!)
> > In fact, do these two things in this order:
> > (1) Explain what 'precision language' means to you.
>
> I have no idea what 'precision language' is.
don't you really mean to say, "I have no idea what 'atonality' is"??
>(snip)
>
> Craig Clark
In addition- I don't think you have much of a concept of tonality either. Oliver
Messian (I probably spelled his name incorectly, so don't go saying whatever) had
written several *TONAL* (because they had a *TONAL CENTER*) pieces in addition to his
*ATONAL* (because they DIDN'T have a *TONAL CENTER*) that were just as dissonant (or
consonant, depending on how you look at it) as the most of his pieces. This is because
he would use a poly-modal aproach in some of his peices, where say the Tonal center was
C, he would have the consonant chord spelled C E Eb G, or something like that, and the
"disonant, or leading chord" be some form of V (or G).
Subject: Re: A Vacuous Problem.
From: jac@ibms46.scri.fsu.edu (Jim Carr)
Date: 12 Jan 1997 03:53:17 GMT
Keith Stein writes:
>
> What happens when AN ELECTRON MEETS A POSITRON IN A VACUUM ?
>
> +e -> ? <- -e
The answer depends on the energy involved, but in general terms
they will scatter some fraction of the time and annihilate some
other fraction of the time, perhaps after forming positronium
and emitting some photons. Annihilation will give you a minimum
of two photons at low energy, with the possibility of making
anything from charmonium to pairs of W bosons if you have a great
deal of energy carried by the two particles.
> We can't balance energy and momentum after they collide. Right?
Wrong. Look at some of the data from CERN on the web at high
energy, or the positronium data at low energy.
--
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.
Subject: Re: Why can't 1/0 be defined???
From: David Kastrup
Date: 17 Jan 1997 13:19:46 +0100
tkidd@hubcap.clemson.edu (Travis Kidd) writes:
> You cannot give reasons in mathematics, except for reasons why
> (actually how) we know something to be true. 0^0 is
> indeterminate--possibly on all the reals, possibly only between 0
> and 1.
Wrong. An expression involving only constants is *never*
indeterminate. It either has a value, or is undefined.
The function x^y is indeterminate at (0,0). That's an entirely
different thing. It means that lim (x,y)->(0,0) x^y does not exist.
This is commonly called an indeterminate limit.
An expression involving limits can be undefined because the function
the limit is taken of is undeterminate at the limit.
Fine distinction.
But for a function to have limits, it needs to have values. And where
it has values is the mathematicians' decision. It turns out that
0^0=3D1 has decidedly more important reasons supporting it than other
choices have which is why today's general consent is that it is the best
definition. See the appropriate section of the FAQ for more info.
--
David Kastrup Phone: +49-234-700-5570
Email: dak@neuroinformatik.ruhr-uni-bochum.de Fax: +49-234-709-4209
Institut f=FCr Neuroinformatik, Universit=E4tsstr. 150, 44780 Bochum, Germa=
ny
Subject: Re: Idle query: how good are math and science teaching outside the U.S.?
From: mert0236@sable.ox.ac.uk (Thomas Womack)
Date: 17 Jan 1997 11:34:42 GMT
M.LJoyce (martin@kimmi.demon.co.uk) wrote:
: Anyway, I still can't figure the inverse Laplace transform of
: s^2/(s+a)(s+b), any help ?
: P.S. Is there a DERIVE fan club out there, or has windoze got you all
: MATLAB ?
I'm a MAPLE zealot. It's available on the Massive Great Server here.
>readlib(laplace):
>invlaplace(s^2/(s+a)*(s+b),s,t);
3 2 2
- a exp(- a t) + Dirac(2, t) - a Dirac(1, t) + a Dirac(t) + b a exp(- a t)
+ b Dirac(1, t) - b a Dirac(t)
(which I think can be simplified to
a^2(b-a)exp(-at) + Dirac(2,t) - (a-b)Dirac(1,t) + a(a-b)Dirac(t) )
[where Dirac(n,t) is the n'th derivative of Dirac's delta function evaluated
at t].
: --
: Martin@kimmi.demon.co.uk
: "the crux of the biscuit is the apostrophe"F.Z.
--
Tom
The Eternal Union of Soviet Republics lasted seven times longer than
the Thousand Year Reich
Subject: Re: paradox
From: owl@rci.rutgers.edu (Michael Huemer)
Date: 17 Jan 1997 08:36:59 -0500
This is the first message in this thread that I've seen (because the
first that's appeared in sci.philosophy.meta), so I'm here risking
repeating things that have already been said. Nevertheless...
>: > : > Thus all of the non-black things you find which
>: > : > aren't ravens (your red coat, the white ceiling, etc.)
>: > : > also support your generalization that "all ravens are black".
>: >
>: > Hm, isn't there a name for this paradox? 'Hempel paradox' or
Yes, it's called the Ravens Paradox.
>: This is not a paradox. The statement "all non-black things aren't
>: ravens" is the contrapositive of the hypothesis "all raven's are black.
>: Mr. Allen is correct; the two statements are logically equivalent.
Yes, they are logically equivalent, but yes, it is still a paradox.
(see below)
>: I'd not call the ornithologist lazy, however. In order to prove the
>: hypothesis (all ravens are black) by demonstrating the contrapositive,
>: he'll have to examine each and every non-black item and show that
>: none of them are ravens. I'd call that a more daunting task even than
>: checking up on all the ravens.
I think you've misunderstood the paradox. Let me explain it. First,
the paradox is about 'confirmation.' Confirmation is a relationship
between propositions. "A confirms B" means that A provides *some*
evidence, some support, for B. Note that it does not mean either of
the following: (a) that it absolutely proves B (i.e. entails B), or
(b) that it provides enough support that we should believe B. Rather,
A confirms B just means that A provides *at least some* support,
however small, to B. And of course, if you get *enough* confirmation,
then you get a justified belief (so the other two relations I
mentioned are *species* of confirmation).
Now, most of our knowledge, including all oour scientific knowledge,
is based on evidence which confirms but does not entail it. The
concept "confirmation" is clearly central both to philosophy of
science and to epistemology generally.
It would be nice to hae a theory of confirmation (something analogous
to the systems of deductive logic that we already have) - something
that would tell us when we have confirmation and when we don't. Of
course, the best thing would be if we could precisely measure
confirmation (e.g., "there is 57% confirmation between A and B
here..."), but the least we could hope for is a *qualitative* account
of when A confirms B.
Here's a start at that. Here are some intuitively plausible
principles that ought to govern the 'confirmation' relation:
1. The observation of an A that is B confirms "All A's are B."
2. The observation of an A that is non-B disconfirms "All A's are B."
3. The observation of a non-A is irrelevant to (neither confirms nor
disconfirms) "All A's are B."
4. If P is logically equivalent to Q, then whatever confirms P
confirms Q.
(The first three principles are collectively called "Nicod's
criterion".)
The Ravens Paradox results because we see that these 4 principles,
which at least appear obviously true, are inconsistent. For consider
the observation of a white shoe. This object is a non-black
non-raven. Therefore, by (1), it confirms "All non-black things are
non-ravens." But "All non-black things are non-ravens" is logically
equivalent to "All ravens are black." Therefore, by (4), the
observation of a white shoe confirms "All ravens are black." However,
by (3), the observation of a white shoe is irrelevant to whether all
ravens are black.
Thus, one of these principles has to go. Which one?
--
^-----^
Michael Huemer / O O \
http://www.rci.rutgers.edu/~owl | V |
\ /
Subject: Re: A case against nuclear energy?
From: Greg Chaudion
Date: Fri, 17 Jan 1997 10:21:05 -0500
steve perryman wrote:
>
> Greg Chaudion wrote:
> >
> > Jim Carr wrote:
> >
> Who's defending evil? What's the death of a few civilians compared to
> all life on the planet? It may sound cruel, but given the choice I would
> sacrifice a few (yes, even myself) if I was absolutely sure that it would
> preserve more life than it would destroy.
I was going to reply, but I don't think that I have anything to say.
I had hoped that people were moral enough not to fall for the same
sort of crap that criped Europe in the 30's, but I guess I was wrong.
There will aways be some greater good that gives you the right to
kill innocents, some great evil that gives you the right to
throw prisoners into icewater tanks, or expose service men to
fallout. Not that other methods arn't almost effective, not that
caution be damn, whats a few lives when its for the fatherland.
Subject: Re: Utter Futility of Arguing With Creationists
From: "R. Alan Squire"
Date: Fri, 17 Jan 1997 05:19:03 -0800
I think that this line of argument should be retitled "The Utter
Futility
of Arguing with WF3H." Hell if I were as captious and narrow-minded as
you, I wouldn't reveal my name either. As I already pointed out in my
previous reply, the remark...
>>The idea that religion equals Christianity may be too narrow a view for
>>these arguments.
...was simply an opening to my rather uncritical response.
>>No, you did not specifically equate Christianity with religion.
>well then whats your point? dont point words in my mouth only to take
>them out to try to prove me wrong. use your own words. you seem to
>have enough
My point is (and has been) that science may well fall into the category
of religion since it relies on SOME degree of faith. It's amazing that,
despite my apparent verbosity, you seem invariably to zero in on one
detail.
>>Christ-
>>ianity has, however, been discussed througout most of the discussions,
>>including yours.
>nope, since not only xtians are creationists (but only BIBLICAL
>LITERALISTS are) your point is wrong. i cant help it if you read more
>into my words than what is there. you might need to think before
>typing
Not so. Creationism is the belief that the universe and the life
within it are to be attributed to an extraordinary cause. So a
Taoist or a Hindu could be said to fall into this category.
>>According to the Oxford English Dictionary...
>>
>> RELIGION ... 2) a particular system of faith. 3) a thing that one
>> is devoted to.
>so collecting trains is a religion? idiotic. its apparent the OED was
>discussing a slang useage. you might not be a biblical literalist but
>you certainly are an OED one
Collecting trains is not a system of faith. And I suspect that you're
taking the term "devoted" a bit lightly. Furthermore, the OED uses
the designation "(slang)" when it describes such a usage. However,
if you prefer a more professional definition:
"If religion is taken in its widest sense, as a way of life
woven around a people's ultimate concerns... if religion is
taken in a narrower sense, as a concern to align humanity
with the transcendental ground of its existence..."
I'm quoting Huston Smith -- probably the foremost authority on the
religions of the world. If you wish to dismiss his insights, you'd
be in very poor company. And if you're apt to suggest that the
term "transcendental" marks the dividing line between science and
religion, you should first consider that many scientific theories
to which eminent physicists subscribe begin as intuition and remain
that way. E.g., many scientific explanations for a quantum
particle's strange behavior are, for all intents and purposes,
metaphysical. The very fact that so much dispute exists -- that
different scientists are willing to sanction so many contrasting
ideas -- is evidence of scientific faith. Science does not and
could not rely solely on evidence.
>wrong. religion is teleological and uses faith to understand its
>teleology. thats religion. the other is empirical and uses evidence.
>science is not voodoo.
Do you deny that science also has end goals? Any experiment begins
with an hypothesis. (And a researcher is not usually quick to
dismiss it when the results are less that satisfactory.) Evidence,
interpretation, AND conviction are used to substantiate the
results.
Subject: Re: Creationism? crap!
From: glhansen@copper.ucs.indiana.edu (Gregory Loren Hansen)
Date: 17 Jan 1997 15:53:40 GMT
In article <32DEBA14.4EF25F9F@alcyone.com>,
Erik Max Francis wrote:
>Jonny wrote:
>
>> Hey guys, this is a physics site! If you want religious clap-trap
>> go to those pages.
>
>No, this is a physics _newsgroup_. Please learn the difference between
>Usenet and the World Wide Web.
I can't believe anyone would be so pissy about something as trivial as
this. Anyway, the world wide web has _pages_. "Site" is a completely
generic term for "location", and John's useage was appropriate.
--
"Good things come in small packages. But big things can't, unless they're
inflatable or require some assembly." - The Tick
Subject: Re: IS THERE A CASE FOR THE ELECTRIC CAR?
From: glhansen@copper.ucs.indiana.edu (Gregory Loren Hansen)
Date: 17 Jan 1997 15:42:53 GMT
In article <5blj07$652@bugle.nb.rockwell.com>,
Jim F. Glass x60375 wrote:
>The electric car is, to put it gently, a crock.
>
>Look at the energy density of the best batteries versus that in a
>tank full of gasoline.
>
>To make them even marginally practical, they must shave weight
>like maniacs--what you get is a toy car with high-pressure tires.
I guess that's why research is still being done on them. They're not
currently practical for anything but commuting and trips to the grocery
store. But that covers an awful lot of traffic. The streets might be
quieter and smell nicer if more people used them.
(Or, for that matter, rode a bike. Or pushed a hand cart to the grocery
store. But that's health vs. conveniance, a completely different
argument.)
>How would such a vehicle be air conditioned? The A/C system might
>well use more power than the rest of the vehicle...not a prescription
>for long range.
Isn't the range limited to sixty or a hundred miles with the A/C?
>The "EV-1" being "sold" here in CA requires something like a $4000
>installation in your house for the charger. They are being leased,
>not sold, because nobody would be able to afford the price--even though
>it is heavily subsidized.
$4000 for the charger? So it can't just run off the 220V line? That
seems prohibitively expensive.
>I will one of these days do the calculation of the impact on the power
>grid if ALL cars were to convert to electric. The output of the calculation
>would be the number of new nuclear and/or fossil power plants that would
>have to be built to supply the energy. Right now, there are so few
While you're doing your analysis, keep in mind that every new load on the
power grid is one less tank being filled with gasoline. Large power
plants have better efficiency than internal combustion engines. Calculate
the cost of processing the fuels. Gasoline is highly refined, while power
plants can burn coal, crude oil, and natural gas. Nuclear fuel is also
highly refined, but it has such a high energy density, it's not obvious to
me if it costs more or less per unit of energy that you can get out of it.
>Electric cars would be (and have been) utterly rejected by consumers and the
>free market: a clear sign that they are impractical. And that
Automobiles took a long time to catch on, too. And that only after the
U.S. government put a lot of money into building paved roads. But I'll
leave you to decide if it's a good thing or bad thing that they did.
--
"Good things come in small packages. But big things can't, unless they're
inflatable or require some assembly." - The Tick
Subject: Re: Utter Futility of Arguing With Creationists
From: wf3h@enter.net
Date: Fri, 17 Jan 1997 13:57:41 GMT
On Fri, 17 Jan 1997 05:19:03 -0800, "R. Alan Squire"
wrote:
>I think that this line of argument should be retitled "The Utter
>Futility
>of Arguing with WF3H.
i would be honored if you would cease doing so since your posts are
tedious and ill argued
>>>The idea that religion equals Christianity may be too narrow a view for
>>>these arguments.
>
>...was simply an opening to my rather uncritical response.
>
and had no relationship whatsoever with my position. so why bother
with it as an opening?
>
>My point is (and has been) that science may well fall into the category
>of religion since it relies on SOME degree of faith.
do you know what religion is? you dishonor those who ARE religious by
twisting the word to mean what ever is convenient for you. faith and
experience are not identical. religion is teleological; science is
not. you cant slide science under the door of religion by attempting
some false sythensis of the 2 concepts
It's amazing that,
>despite my apparent verbosity,
believe me, its not only 'apparent'...its very real
>>nope, since not only xtians are creationists (but only BIBLICAL
>>LITERALISTS are) your point is wrong. i cant help it if you read more
>>into my words than what is there. you might need to think before
>>typing
>
>Not so. Creationism is the belief that the universe and the life
>within it are to be attributed to an extraordinary cause. So a
>Taoist or a Hindu could be said to fall into this category.
none of them want it accepted as scientific fact
>
>>>According to the Oxford English Dictionary...
>>>
>>> RELIGION ... 2) a particular system of faith. 3) a thing that one
>>> is devoted to.
>
>>so collecting trains is a religion? idiotic. its apparent the OED was
>>discussing a slang useage. you might not be a biblical literalist but
>>you certainly are an OED one
>
>Collecting trains is not a system of faith.
its something one is devoted to. thats the context you tried to use on
science...that because one is devoted to science it can be considered
a religion.
> . And if you're apt to suggest that the
>term "transcendental" marks the dividing line between science and
>religion, you should first consider that many scientific theories
>to which eminent physicists subscribe begin as intuition and remain
>that way.
and intuition has nothing to do with transendence
E.g., many scientific explanations for a quantum
>particle's strange behavior are, for all intents and purposes,
>metaphysical.
and metaphysics is not necessarily transcendent
The very fact that so much dispute exists -- that
>different scientists are willing to sanction so many contrasting
>ideas -- is evidence of scientific faith. Science does not and
>could not rely solely on evidence.
and in the end it does. because if it doesnt, its just not science.
any theory in science must be testable. it must be based on evidence.
>
>>wrong. religion is teleological and uses faith to understand its
>>teleology. thats religion. the other is empirical and uses evidence.
>>science is not voodoo.
>
>Do you deny that science also has end goals?
science is a method used to investigate nature. it does not assign a
purpose to human existence. it is not transcendent
Any experiment begins
>with an hypothesis. (And a researcher is not usually quick to
>dismiss it when the results are less that satisfactory.) Evidence,
>interpretation, AND conviction are used to substantiate the
>results.
and none of these is transcendent
Subject: Re: Astrology: statistically proven now!
From: bill@dont.spam.me.org (Bill Jefferys)
Date: 17 Jan 1997 16:26:37 GMT
In article <19970117105000.FAA06394@ladder01.news.aol.com>, lbsys@aol.com wrote:
> Im Artikel ,
> mmcirvin@world.std.com (Matt McIrvin) schreibt:
>
> >On the other hand, the probability of getting a chance
> >anticorrelation *or* a chance correlation this strong for
> >*any one* of the 144 combinations is about 1 in 36, if
> >my calculations are correct.
>
> That' the interesting part. Indeed if it was only one of the 144...
>
> > That's not so much
> >overwhelming as somewhat unusual and possibly
> >suggestive (whether of a real effect or of some sort of
> >bias, I don't know).
>
> Yes
>
> >Of course, they apparently got more than one significant
> >result, so that would correspondingly decrease the probability.
>
> Exactly. As I understood they had about a dozen correlations over
> significance level. And then there was the run with those constructed
> virtual starsign giving nothing but statistical random noise.....
Several points:
1) If it is p-values that are being calculated (I don't know this from
what's been written, but it is what is usually done in such research),
then they are not interpretable as the probabilities of getting the
results in question by chance. In fact, p-values are very difficult and
tricky to interpret, and mostly give misleading results that understate
the actual probabilites by factors typically of 10 or more. This is
because the tail-areas that p-values represent are mostly irrelevant to
the particular results that _were_ obtained, and hence to their
probabilities. See James O. Berger and Mohan Delampady, "Testing Precise
Hypotheses," Statistical Science (1987, vol. 2, No. 3, pp. 317-352) for
details.
2) Even worse, given a large enough data base, p-values will with
probability as close to 1 as desired, reject even hypotheses that are
actually and exactly true.
3) On the other hand, point null hypotheses are rarely if ever exactly
true, so hypothesis tests that test point nulls hardly ever tell us
anything that we don't already know. In the present context, it is
virtually certain that defects in the data set (some of which have already
been mentioned in this thread) will guarantee that there is some effect.
The question is, is the effect of practical interest?
4) Finally, one has to be careful when looking at multiple possible
correlations on a given data set, since the existence of one correlation
will increase the probability of others being present. This is a
consequence of the fact that the probabilities in question are not
independent. Thus, one can take the error of regarding a p-value as being
the probability that we have observed something unusual, and compound it
by naively multiplying the p-values together. This is most illegitimate.
In general, we are not in fact interested in what the probabilities of
obtaining a particular result by chance are, since almost every particular
result in real life is of low probability. We are actually more likely to
be interested in what the probability of the hypotheses under
investigation are, _given_ that we have observed particular data. This
requires a Bayesian approach.
Bill
--
Bill Jefferys/Department of Astronomy/University of Texas/Austin, TX 78712
Email to clyde.as.utexas.edu | Homepage: quasar.as.utexas.edu
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Subject: Re: PH.D.s are useless
From: candy@mildred.ph.utexas.edu (Jeff Candy)
Date: 17 Jan 1997 14:14:42 GMT
|> >Bruce Salem:
|> >|> The income distribution changes
|> >|> in the U.S. in the past 20 years is evidance that so-called
|> >|> free market economics benefited a small minority and that it leads
|> >|> to winner-take-all processes that disadvantage many more then it
|> >|> benefits. It is the power of timly access to information and the
|> >|> flow of information that causes this.
Jeff Candy:
|> >A free market system is the only rational system. Perhaps
|> >this is why laissez-faire is so poorly understood, and so
|> >often maligned.
Bruce Salem:
|> You don't offer any argument for these assertions.
(i) For the philosophical foundations:
Ayn Rand, "Capitalism: The Unknown Ideal",
(NY, the New American Library, 1967).
(ii) From an economic perspective:
Ludwig Von Mises, "Human Action",
(Chicago, Contemporary Books, 1966)
(ii) For modern economic implications:
Victor Sperandeo, "Methods of a Wall Street Master",
(John Wiley, NY, 1993)
|> I think that we do not in fact have laisses-faire economics,
|> even after Regan, but that we still have a "Mixed" economy in which
|> some of the regulation has been undone.
Absolutely correct. At no point was I making an explicit reference
to a particular country.
|> What change has happened? Technology, notably the personal computer
|> has changed the relationship between labor and management.
Not in any fundamental way.
|> It has created a labor force that has not become collective,
|> yet. One on which all the risks of small business has been
|> pushed with none of the benefits. The tax laws certaintly
|> don't favor the white collor migrant worker or the temporary
|> contract worker.
Now I don't follow you. The current tax laws in the US are
not imposed in a fair, rational way. They are "unfair" for
millions of people.
|> This change really has little to do with government politics,
|> yet it is revolutionary and it is the source for cynicism in
|> our current setting. People feel very much less secure and
|> yet true to American mythos, they speak of the opportunity and
|> play down the risk. We will see what the tune is after the
|> next downturn, and remember that Americans are again putting
|> all their eggs in one basket, as happened in the 1920s. If
|> the Stock and Bond Markets crash, which could happen this
|> year, all hell could break loose.
If this passage were shown to a high school student in 1967,
he'd probably have said, "right on man". Nothing fundamental
has changed.
-------------------------------------------------------------------
Jeff Candy The University of Texas at Austin
Institute for Fusion Studies Austin, Texas
-------------------------------------------------------------------
Subject: "Draw" an electron, you may win fabulous prizes.
From: ale2@psu.edu (ale2)
Date: 17 Jan 1997 16:51:45 GMT
I am offering a staggering $7 (US) prize money for the best "drawing"
of an electron (what is best will be explained below). This contest is
open to all; crackpots, amateurs, professionals (professors seeking
tenure should use a pseudonym), AP, and AA, anyone, from anywhere!
The Rules
1) I pick the winners, 5$ for 1st prize, 2$ for 2nd prize, and some
good photocopies for 3rd prize. I can enter but cannot win.
2) Submit entries by replying to this article no later than midnight
next Wednesday.
3) There is no length limit but excessively long entries will probably
lose the interest of the reader and the judge (me). Entries must be in
English.
4) Winners will be announced on sci.physics one week after contest
closes.
5) Winners must email your address so i can send you your prize. Please
allow 1 week for delivery, 3 week if out of the US.
6) If a majority think i picked the wrong winner, i might change my
mind.
How i will judge the winning entry.
The winning entry will paint or draw for us a picture of an electron
such that this picture "implies" what we know about the electron (see
below). Possibly this picture will also imply something that is not
understood about the electron, for example its quantum nature.
We set our goals high but we will be satisfied if the best entry does
at best a bad job of the above. What i'm saying is this is not an easy
task! But you have to give us something better than "the electron is a
point". Just does not do it for me!
Some of what we know of the electron.
All electrons seem to come with the same mass, the same charge
(electric and weak charge), and the same angular momentum, this would
be nice to explain.
Electrons are best described by the theory Quantum Electrodynamics
which is a marriage of Quantum Theory and the Special Theory of
Relativity.
Electrons are Fermi particles and as such no two electrons can be in
the same state.
In an inhomogeneous magnetic field a beam of hydrogen atoms will be
split into two beams and only two beams.
And on and on. You something about the electron, paint a picture!
If a lot of this doesn't make sense i'm sorry, i'm tired %^)
Subject: Re: Help me with Newton's law F=ma
From: mfein@aplcomm.jhuapl.edu (Matt Feinstein)
Date: Fri, 17 Jan 1997 13:36:30 GMT
orie0064@sable.ox.ac.uk wrote:
>> From: mfein@aplcomm.jhuapl.edu (Matt Feinstein)
>>Because it describes what you actually -do- when you do mechanics,
>>i.e., solve a differential equation. If F = ma were an identity, it
>>would be true for -any- motion of the particle and 'solving' it would
>>be an empty exercise.
>When we solve an equation with force, it's usually in terms of a field.
>eg, with gravitation, it ould be ma=-GmM/r^2.
>What you are doing, is generalizing what "all fields do" into something
>called "force."
The distinction you're making here, that only 'equations with fields'
have the above form, doesn't hold-- all dynamical equations have that
form. For example, Newton's law for fluid motion (to take a specific,
messy example) has the form
density * du/dt = pressure force + body force + frictional force
and, (repeating myself here), this is -not- an identity. The
different forces are distinct physical effects, and the -fact- that
the linear sum of the forces is proportional to the derivative of the
velocity of the fluid particle is not merely an assumption or a
definition of anything, it is a physical law that allows us to
-compute- the motion of the particle.
>I think it's a lot better to assume that "the action of this field is
>that it changes momentum at this rate" and define force from the change
>in momentum.
Again, it's not an assumption, it's a (falsifiable) law of nature
determining the relation between force and motion.
>One advantage is that your way of leaving force undefined
>does not cover bodies with variable mass, eg rockets. Mine does.
Not so. Just replace "ma" by d(mv)/dt at all points in my statements.
>But "undefined concepts" are EVIDENT enough for use to work confortably
>with them without the need for defining them.
>Look at your mathematics example: "point" and "number" are quite
>evident to anyone.
>
>"Force", however, is far from it, since as you said there are so many
>different kinds of it, and it originates from so many different sources.
Well, -I'm- comfortable with it.
Matt Feinstein
mfein@aplcomm.jhuapl.edu
Subject: Re: Happy Birthday, HAL!
From: Jon Haugsand
Date: 17 Jan 1997 16:28:48 +0100
Erik Max Francis writes:
>
> Jon Haugsand wrote:
>
> > And do *you* seriously believe Clarke in this question?
>
> He has no powerful motivating reason to lie. Do you disbelieve anything
> anyone says?
>
> For instance, Murray Gell-Mann insists that the word _quark_ did not
> originate from Joyce's _Finnegan's wake_. Is he lying, too?
No, I do not "disbelieve anything anyone says". Why do you think so?
I have not read Joyce's "Finnegan's wake", so I cannot answer the
question. Have you read it?
--
Jon Haugsand
Dept. of Informatics, Univ. of Oslo, Norway, mailto:jonhaug@ifi.uio.no
http://www.ifi.uio.no/~jonhaug/, Pho/fax: +47-22852441/+47-22852401
Subject: Re: A case against nuclear energy?
From: Mark Friesel
Date: Fri, 17 Jan 1997 08:47:58 -0700
Greg Chaudion wrote:
>
....
>
> I was going to reply, but I don't think that I have anything to say.
> I had hoped that people were moral enough not to fall for the same
> sort of crap that criped Europe in the 30's, but I guess I was wrong.
> There will aways be some greater good that gives you the right to
> kill innocents, some great evil that gives you the right to
> throw prisoners into icewater tanks, or expose service men to
> fallout. Not that other methods arn't almost effective, not that
> caution be damn, whats a few lives when its for the fatherland.
MF replies:
I'd feel much better if, instead of apologists, one of our icons of
intelligence would state that such activities are failures tha we were
unable to avoid. No-one was able to come up with a better solution -
one that would accomplish the desired objectives without requiring an
immoral or unethical act.
I have more respect for someone who would say, 'No, I just enjoyed
experimenting on people', or preferably 'We couldn't think of a better
solution' than the apologists who try to say that there was no better
solution.
