Subject: Constitutions of Matter: Mathematically Modeling the Most Everyday of Physical Phenomena (fwd)
From: krieger
Date: 30 Nov 1996 05:15:58 -0800
University of Chicago Press has just published my new book with the above
title. It examines proofs of the stability of matter, and the very many
solutions to the Ising model, to better understand how the technical
mathematics does "physical" work, making clear just what is the physics in
each case. The figures include Onsager; van Hove and Fisher and
Ruelle; Lenard and Dyson; Lebowitz, Lieb, and Thirring; and Onsager; Yang;
Lee and Yang; Schultz, Mattis, and Lieb; McCoy and Wu, Baxter--not to
mention many others who have contributed to these programs of research.
It will interest physicists and chemists, mathematical and theoretical
physicists, some mathematicians, and those concerned with the philosophy
and history of these subjects. It helps to have a proper technical
training, but I have written the book so that those who are trained in
philosophy and history of science can follow the argument.
The appendix reproduces two of Onsager's crucial papers, one on the
stability of matter, the other the 1944 paper on the Ising model.
The book is available from your bookstore, or from the University of
Chicago Press at 1 800 621 2736, ISBN=0 226 45304 9. It will be a Library
of Science selection.
Martin Krieger
University of Southern California
Los Angeles CA 90089-0042.
PS. An earlier book of mine, Doing Physics: How Physicists Take Hold of
the World (1992) is available from Indiana University Press at 800 642
8796, ISBN=0 253 33123 4. It too was a Library of Science Selection.
Subject: Re: Causality Violation
From: erg@panix.com (Edward Green)
Date: 30 Nov 1996 10:52:03 -0500
Peter Diehr wrote:
>Edward Green wrote:
>>
>> In addition to the observed structure of special relativity, let us
>> arbitrarily single out a fixed frame of reference, and let us
>> introduce a new kind of particle, the tachyon, which for concreteness
>> suppose always travels at 1.5c *relative to this fixed frame of
>> reference* (naturally in other frames of refernce it would either be
>> seen to be moving faster or slower than light according to the
>> behavior of its world line as plotted in the variables of that
>> frame -- which is what you saw as the nonsensical nature of my
>> proposal, that I seemed to deny this).
>
>You would need to propose more physical consequences before I
>would hazard a guess about this system. It is my belief that
>tachyons are ruled out for physical reasons ... such as going
>shedding energy as they go faster ... and that they are no
>longer taken seriously except on Star Trek.
>
>> I merely assert that this is a self-consistent way the universe
>> could be, not ruled out on the basis of "casuality violtations".
>> Do you see the distinction?
>>
>
>I see how you are making a distinction, but I'm not sure that
>your assertion of self-consistency is valid.
Let me emphasize I am only making a kinematical assertion -- that such
a kinematics would be self-consistent with respect to causality,
not proposing a new dynamics -- and reiterate that the
initial assertion seems to have been "tachyons are ruled out by
causality violations". Well, actually even that is too strong;
let's say "would require over-determinism to eliminate logical
paradoxes". I merely want to qualify this (I assert) by adding that
relaxation of the requirement of Lorentz invariance may also be
sufficient. OK, let me make one more attempt to give a simple
argument for this assertion.
First of all, I think it is clear that seen from a single reference
frame, signal propagation with *any* velocity, even instantaneous,
can hardly lead to causal paradoxes -- as long as effects cannot
propagate backwards in time (the time of that frame).
Now I propose that if a description of the universe is free of paradox
in one frame of reference, it must be free of paradox in *all* frames
of reference. This is not a big deal, I hope -- I am just being sort
of pedantically explicit. How does a temporal paradox arise anyway?
It must be that some event is able to initiate a sequence of effect
that bites its own tail, so to speak. You execute action A, and the
effect wraps around in your proper time, to prevent you from
executing action A. Well, suppose such a loop would exist in any
frame of reference... then it would exist in all. How can the choice
of coordinates alter anything?
I sense tension here... and I think I can anticipate its form. One
problem seems to be that relativistic pedagogy emphasizes the
independence of physical law from the frame of reference. But of
course! How could the behavior of the universe depend on the
coordinates we use to describe it? It's tautological -- and also does
not have much to do with special relativity. It's the invariance of
physical law *in form* with respect to a certain group of
transformations that is the non-trivial content.
>There are many types of mathematical schemes, all of them perfectly
>logical, which do not describe physical reality. Some are more
>useful than others (e.g., Newtonian mechanics). But logical
>consistency is not sufficient for the creation of a physical theory;
>it is only a pre-requisite.
I never thought differently. I am only making a logical distinction,
not proposing a new theory. So if someone says "tachyons are ruled
out on logical grounds" I would say "Not so fast. They indeed would
have logical consequences... either over-determinism, or breaking
Lorentz symmetry of physical law, or maybe some other possibility that
I have not thought of -- like some branching or many-world scheme.
But we can't simply rule out the possibility for all time on logical
grounds."
>I'll leave it to you to explore your idea a bit further.
By the way, it is hardly my idea... I just don't know who to grant
precendence to.
>I would suggest the following, for starters: consider how tachyon
>transmitters could be used, and if they could be used to send messages
>backwards in time.
>
>Also consider how physical laws would be modified in this one absolute
>frame of reference ... the assymetry of the general laws seems to
>require this. Conservation of energy seems to go out the window ...
Would it? You mean the ordinary relativistic form of conservation of
energy would not work? Perhaps. I think this is just muddying the
waters though -- you try to push me to make some cockamamie dynamics
for these things which of necessity would probably appear ridiculous.
I will leave that to the universe should she see fit to present us
with this phenonmenon; I feel sure she will be able to work out some
pleasing and consistent scheme. :-) Naturally if Lorentz invariace
turned out to only be an approximate symmetry then things might not be
quite so nice as we expect up to now.
You know, if there is one scintilla of doubt I harbor about the local
correctness of special relativity, it is the absolute nature of the
Lorentz symmetry. Oh, it is damn good, by current standards of
measurement, no doubt about it, and perhaps there is no experimental
evidence now that it is not absolute. But then, the same could once
have been said about Gallilean invariance of physical law. It seems
to me that intellectually, we would want to give this the same
Bayesian prior as the equivalence of the charge of the proton and the
electron... now there is something that is *obviously* true :-)... and
yet it has been checked to high precision and at considerable expense.
Well, I just suggest we regard the absolute Lorentz invariance of
physical law with the same kind of faint skepticism... not as
something we expect to fail, but as a possibility somewhere in the
back of our mind as something that just might not be so.
Thanks for your patience.
Ed
Subject: Re: faster than light travel
From: CCD Data Acquisition
Date: Sat, 30 Nov 1996 11:27:15 -0500
Jean-Joseph JACQ wrote
> ...
> And furthermore, it is a well known fact that the phase velocity in a
> wave guide often exceeds the speed of light in vacuum. But again, the
> actual modulation (ie information) travels slower than C).
> So faster than light is possible but not for mass or information
> transfer.
> Which is also why the quantum phenomena do not break the laws of
> relativity. If a particle/antiparticle are created, and one is left to
> travel 1/2 way across the universe, then someone examines say the spin
> of the particle which remained on earth, then instantly the spin of the
> twin particle will suddenly also be fixed (seemingly against the laws of
> relativity) but since the examination of the spin on earth is a
> completely random process (it can end up either + or - and we can't
> foretell which it will be) then there is no way that we can use it for
> communication hence information can't be transmitted this way.
>
> Isaac Asimov's hyperwave transmissions won't work, they'll only generate
> static noise.
>
> John
Consider the following. The quantum state described above is known as
a spin singlet state, denoted in Dirac notation, as |psi> = C ( |+,-;z>
+ |-,+;z> )
where a = 1/sqrt(2). Suppose we have a device which generates particles
in
a spin singlet state as illustrated below:
---
/ \
------ SSG -----
\ /
---
To be definite about the state |psi> in relation to the spin singlet
generator (SSG) we will define |+,-;z> as the state where the particle
traveling to the left is in the spin state |+;z> and the particle
traveling to the right is in the spin state |-;z>. The "z" denotes that
the spin measurements are made along the z-axis. Then, for example
the eigenstate |+,-;z> is the tensor product of |+;z> and |-;z>, i.e. if
*
represents the tensor product then |+,-;z> == |+;z>*|-;z> (== means "is
defined as").
Now we need a device which will measure the spin, a Stern Gerlag (SG)
type device. Let the device be illustrated as follows:
--------
| +|----
--------- SSG ----------|- (1')| \ / | (1) -|--| ----------
[Moe]----|- (2')| -------- --- --------
--------
Note: N' always measures after N does
At this point we need the relation |+,-;z> = C ( |+,-;x> - |-,+;x> > )
(See Sakuri, Modern Quantum Mechanics, Addison Wessely, Reading MA).
Particles moving to the right will be
refferd to as R and those moving to the left will be reffered to as L.
With this relation
we can describe how this system works. Consider a pair of particles in
the state |psi>
created by the SSG. If device 1 detects spin up on R then device 1' must
detect spin down
i.e. the system will be in the state |psi(1)> = |+,-;z>. The
probability of this
measurement is 1/2. Now comes the tricky part. If the switch (z,x) is
in the z position
then detector 2 (Joe) will measure spin up with a probability of 1
(given that detecxtor 1 measured spin up). This means the state remains
in the eigen state |+,-;z> and detector
2' (Moe) will measure spin up. However if the switch is in the position
x then, given
detector 1 measures spin up the probability that 2 will measure spin up
(along x) is no
will be 1/2. Lets look at this more closely. After detector 1 measures
spin up the
system will be in the state |+,-;z> = C ( |+,-;x> - |-,+;x> ). This
means that if the
x component is measured the system will be in either the state |+,-;x>
or the state
|-,+;x> the probability of each state being measured being 1/2.
Therefore Joe will get
either spin up or spin down (along x). Same with Moe. To be more clear
let us asume
that these spinglet states are produced in large quantities so there is
a beam of particles.
We'll call the beam current I (measured in particles per second) then
device 2 will recieve
a current of I/2. and so will 1'. If the switch is in the z position
then Joe will recieve
a beam current also of I/2 same as Moe. However if the the switch is in
hte x position
then Joe will get a beam of I/4 same as Moe. If Joe has controll of the
switch then he can
change what Moe recieves as a beam current. Hence communication quicker
than that which would have been delivered by light (notice the choice of
verbs). Also note that relativity
is not violated in that nothing, no particle, is actually travling
faster than light.
Regards
Peter M. Brown
Subject: Re: Universal Coordinate System
From: odessey2@ix.netcom.com(Allen Meisner)
Date: 30 Nov 1996 17:18:07 GMT
In <329FC201.F3D@mail.ic.net> Peter Diehr writes:
>
>Allen Meisner wrote:
>>
>>Peter Diehr said:
>> >
>> >Let's check this out:
>> >_ _
>> >a = d(v)/ds, where I'm now using s as the arc length of the path
>> >of the light beam. We have found the acceleration of the light
>> >beam. Are we correct in equating this with the acceleration of
>> >the ship? It seems to be, since the bending of the beam is due
>> >to the acceleration of the ship.
>> > _
>> >Now to get v we have to integrate wrt s, the arc length. When
>> >we do this, we get an arbitrary constant for each spatial
>> >dimension: that is, we get
>> > _ _
>> > v + c, the desired velocity of the ship, plus another, unknown,
>> > arbitrary velocity.
>>
>> Not an arbitrary constant, but the instantaneous velocity since
the
>> ship is accelerating and the velocity is changing with respect to
time.
>
> _
>The constant vector, c, is the constant of integration.
>
>> The "arbitrary constant" is the slope of the curve, which gives you
the
>> instantaneous velocity at that point in time.
>
> _ _ _
>No, now you are describing v. But we have measured a, not v!
>That is what we get when we measure the curvature: the acceleration.
>We can only tell the direction of the velocity, but not its
>magnitude from the information given.
>
>> At t=0 the velocity is a
>> certain value. At t=1 the velocity has increased, because the ship
is
>> accelerating. At t=2, the velocity is greater than at t=1. Each time
>> value is a point along the curve. If you take the derivatve at that
>> point you get the instantaneous velocity at that point in time.
>>
>We seem to have a calculus problem now ... or perhaps a problem of
>interpretation. What is it that we are measuring here? Certainly
>the velocity is increasing, because of the acceleration. Suppose
>we again take a simplified example: let's roll balls across the
>floor of a moving train, transverse to the direction of travel.
>With the modern "seemless rails", we aren't supposed to get any
>clickety-clack, so we have a simulacrum of an inertial reference
>frame while we are on the straightaway on level ground, and the
>train is holding a steady speed.
>
>Now suppose we've dusted the floor, so that each ball rolled leaves
>a visible track. When we begin, the train is moving at a constant
>velocity (straight ahead, fixed speed). So the track of the ball
>is a straight line across the floor. Now the train begins a
>gentle, constant acceleration. We note that the balls now curve
>towards the rear of the compartment. By measuring this curvature,
>we can ascertain the acceleration.
>
>Bravo! So we can determine from this the incremental change in
>velocity ... after so many minutes, we can compute the total
>increase in velocity obtained: delta v = a*t.
>
>But unless we already knew the original speed of the train,
>we have not got a way to say how fast we are going wrt the rails
>below.
>
>To determine that, we must look out the windows, and establish
>our ground speed by means of landmarks (counting the rate at
>which the telegraph poles go by, or counting the rails, etc.).
>
>So let's go back to the point of difference: do you think that
>we can find the initial velocity of the ship because I have made
>a calculus error (i.e., that I should be able to determine the
>velocity at t=0 from the data given), or that you are claiming
>some other physical evidence that I have ignored?
>
>Best Regards, Peter
The path of the light is a curve. If you take the first derivative:
d=.5at^2, d'=at, and substituting time, you get the instantaneous
velocity. This is the tangent to the curve at that point in time. The
slope of the tangent is the instantaneous velocity. Now on the
velocity-time graph we take the second derivative d''=a and get the
acceleration. The absolute velocity is determined by the straight,
diagonal path of the light toward the rear of the plane. Since
acceleration causes the light to curve back, constant velocity causes
the light to go diagonally back in a straight line. This is because, as
I have told you, I am assuming light is inertialess. After the
acceleration the light will not return to a straight up and down, or
back and forth position. It will remain deflected diagonally back in a
straight line by an amount proportional to the absolute velocity given
by the acceleration. The velocity is absolute because it is measured in
reference to the beam of light which is at absolute rest in the
direction that the ship is traveling. It does not matter what your
initial velocity is. The magnitude and direction of the deflection of
the light will give you your absolute velocity. You can calculate this
velocity in two ways. You can take the derivative of the equation of
the line, y=mx+b. This will give you the slope, which is constant
because the graph is a straight line. The slope is equal to the
absolute velocity. Or you can measure the distance between the point to
the rear of the source, where the light hits the opposite wall, and the
point directly across from the source on the opposite the wall, the
distance d in the diagram. You then calculate the time that the light
takes to go from the source to the point directly opposite the wall,
the distance d' in the diagram. Since the speed of light is c this time
t is d'/c. Dividing the distance d, by the time, t gives you the
absolute velocity, d/t.
____________________________________d_______________opposite wall
\ |
\ |
path \ |
of light \ |d'
\ |
\|
---------------------------------------^------->velocity of ship
light source
Subject: Re: A photon - what is it really ?
From: Robert Fung
Date: Sat, 30 Nov 1996 12:19:09 -0800
Ray Tomes wrote:
>
> Peter Diehr wrote:
>
> >I've never seen any claim made that Planck's constant can be derived
> >from classical physics ... unless one adds at least one new ingredient
> >to the pot: you have to assume quantization in some fashion.
>
> >But if you know of a way, I'd love to look at it.
>
> I cannot derive the value of Planck's constant from classical physics
> but I can show that such quantised behaviour is natural from classical
> physics. It is a long story and this account is necessarily over brief,
> but starting from only Maxwell's equations and GR (which shows that
> there is a non-linearity in Maxwell's equations due to energy bending
> space-time) it is possible to deveop my harmonics theory.
>
> It predicts that, starting from the size of the universe, at scale
> ratios of around 34560 there will be stronger e/m waves. The predicted
> values agree well with the observed distance scales of galaxies, stars,
> planets, moons, .. cells, atoms and nucleons. At several of these
> scales the observed detailed structure also supports the predictions at
> a very high significance level.
>
> For the electron the observed ratio of energy between the Rydberg/Bohr
> levels and the electron is 37558 which is 2/alpha^2. I cannot exactly
> explain why this exact value occurs (but it is repeated for the fine and
> hyperfine structures) or the ratio of the Bohr radius to the proton
> wavelength which is 40046 but they are of the correct order.
>
> The reason why energy must be absorbed in discrete amounts (I don't
> believe that "flying photons" exist, only that energy is emitted and
> absorbed in discrete amounts by matter) is best understood as similar to
> beats in music. A smaller wave must fit an exact number of times into
> the next larger wave and so any change must produce the wavelength of
> the larger wave as a beat. Or to put it another way the peaks of the
> smaller and larger waves must coincide so the number of waves of the
> smaller wave that fit into the larger wave must change by an integer.
I imagine such would be a useful means of factorization or
primality testing is it could be done quickly and accurately
enough. It would be interesting if there were some elegant
relations for prime atomic numbers like He being the only
even prime atomic number will have certain unique qualities.
There are many kinds of quantization though. There is amplitude
quantization of signals, time quantization of the samples,
quantization from integration, from normalization to unity,
and the quantization for a linear oscillator whose potential
energy is an homogeneous quadratic function, the frequency
is independant of the amplitude leads to hf in QM.
Subject: Re: Universal Coordinate System
From: Ian Robert Walker
Date: Sat, 30 Nov 1996 17:39:07 +0000
In article , Ian Robert Walker
writes
>In article <57etlc$dq9@dfw-ixnews11.ix.netcom.com>, Allen Meisner
> writes
>> Here is a thought experiment that decides the matter once and for
>>all. You are in a spaceship traveling at 1000 meters per second. There
>>is a laser in the nose of the ship that is pointed in the direction
>>perpendicular to the direction of travel. The laser operates in the
>>pulse mode. At time t=0 that laser begins emitting pulses and the
>>thrusters are turned on giving the ship a 10 meter per second squared
>>acceleration. After 1000 seconds, the ship has traveled 6,000,000
>>meters. Will the first pulse still be aligned with the nose?
>
>No.
>
>>If you say
>>yes, you must account for the horizontal component of the light by
>>inertia.
>
>I do not see how the presence, or absence of inertia can impose a
>sideways velocity on the light after it has left the emitter. This can
>no more happen with light than with a ball left behind when the ship
>begins to move.
>
>>If this is true, all the laws of electromagnetism must be
>>revised to take this inertia into account.
>
>EM already takes account of the inertia of light, see photon pressure.
>
>>If you say that special
>>relativity does not apply to accelerated frames, then special
>>relativity is wrong, or deficient, isn't it?
>
>No, no more than claiming Ohms law to be wrong or deficient because it
>does not work with a non-linear resistance.
>
>>Velocity is merely the
>>first derivative of acceleration. If you see the light curve back under
>>acceleration, you would then see the light go diagonally back in a
>>straight line under constant velocity. This is first year calculus.
>
>Do you mean the line produced by connecting the individual pulses, or
>the line representing the track of one of the pulses. I will presume the
>former. (My calculus was a long time ago.)
>
>I agree that your discription is valid, but do not see where it is
>leading. Whether we have absolute or relative motion the two lines will
>be either a curve or a straight diagonal.
Just a small correction the differential is the other way round, but
this does not change my reply.
>
>Consider instead of sending the pulses out into infinity we reflect them
>back from a mirror fixed to the space ship and note if they return to
>the same point. When the ship is accelerating they will not, when it is
>travelling at a constant velocity they will. I think that this effect is
>used to advantage in the Sagnac compass.
Also as demonstrated in the Michelson-Morley experiment.
--
Ian G8ILZ on packet as G8ILZ @ GB7SRC
I have an IQ of 6 million, | How will it end? | Mostly
or was it 6? | In fire. | harmless
Subject: Re: bincancel:24 large binaries:AR745:@@NCM
From: red@redpoll.mrfs.oh.us (Richard E. Depew)
Date: Sat, 30 Nov 1996 18:11:37 GMT
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--
Richard E. Depew, Munroe Falls, OH red@redpoll.mrfs.oh.us (home)
It's over, and can't be helped, and that's one consolation, as they
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-- Charles Dickens, _The Pickwick Papers_
Subject: Re: Creation VS Evolution
From: Judson McClendon
Date: Sat, 30 Nov 1996 12:06:15 -0600
evl@aol.com wrote:
>
> In these "religion vs science" dicussions I've seen the word "Truth" alot.
> I'm wondering if those who uses this word realize that NO ONE - no
> physicist, no philosopher, no christian, no person smart or dumb, has a
> coherent theory of truth (unless they have been keeping to to themselves).
> When I say "theory of truth" I dont mean "is the Bible True or not" I mean
> the the very idea of what "Truth" is, what constitutes it, what kinds of
> things can have the property of truth, can all truths be verified in some
> way and if so, how,... The very idea of Truth is not well understood by
> humans. But, of course, anyone who has thought about this, read a little,
> would know that this has been a topic thought about for centuries by many
> very smart people with no resolution. This isn't my little opintion, go
> ask any philosopher from the smallest community college to Harvard. That's
> why it kills me when someone goes babbling about what is or is not true -
> not only is the idea itself ill-defined, but have the audacity to think
> they somehow have more insight into how the world is than individuals past
> and present who have spend lifetimes studying topics that require more
> intelligence than anyone visiting one of these NGs (including myself) has.
'Jesus saith unto him, "I am the way, the truth,and the life: no man
cometh unto the Father, but by me."' (John 14:6)
--
Judson McClendon judsonmc@ix.netcom.com
Sun Valley Systems http://www.netcom.com/~judsonmc/sunvalley.html
Subject: Re: No Newtonian Theory of Gravitation
From: Peter Diehr
Date: Sat, 30 Nov 1996 14:11:54 -0500
In article ,
meron@cars3.uchicago.edu wrote:
>
> So, before it seems that I go to far off on a tangent, to me a new
> theory begins at such a "branching point" where decisons are made and
> new concepts and ideas introduced (or, possibly, previous concepts
> acquiring a quite different meaning). With Newton, the Three Laws are
> such a point (in physics, then you could separately point to calculus
> in math), there is no doubt that there you witness the birth of a new
> theory.
>
Agreed: this is a theory of mechanics. It gives you a method of determining
future motion based upon the knowledge of current motion _and_ the
type of interaction.
That is, you need to know the force law.
> OK, so how about gravitation. Once the laws of motion were there,
> what else was needed. An assumption that the planetary orbits have
> something to do with some force? Yes, but Newton was already
> committed to the idea that any motion where the velocity changes (i.e.
> specifically, any orbit) is the result of some force. An assumption
> of universality? Yes, but Newton was already committed to
> universality too, his laws were already stated as universal, not
> something valid only in Southern England. So, there was no need for
> new assumption or ideas, only taking the ideas that were already
> embodied in the laws of motion and applying them to the existing set
> of observations which were compiled in such an elegant form in
> Keppler's Laws (I wonder whether Keppler ever realized what an
> amazingly good job he did there). That's why I don't see Newtonian
> Gravitation as an independent theory, only as an (natural) development
> within Newtonian Mechanics.
>
Several points ... yes, Kepler did recognize how good a job he did!
He was very excited about it, and even got a bit carried away. This
isn't too surprising. But when he shared his results with Galileo,
Galileo wasn't impressed. You see, Galileo was very prejediced in
favor of the Copernican system, which retains a system of epicycles.
It took a long time for people to fully break away from the idea
that only circular motion existed in the heavens.
BTW, Kepler also worked on a force law ... and almost got it right.
But I would have to dig around to find what he had proposed.
Universality: yes, Newton's three laws of motion are supposed to
be universal in scope ... but that is not where Newton applied the
term: it is the Universal Law of Gravitation. Here the point was
that that same locally observable force which we call gravity
applies to all objects ... that is, it is not just earthly things
that are attracted to the earth, but all things, in their proper
measure. The proper measure is in their mass, and the reach of the
force is universal.
This was quite a break from Aristotelian ideas, and owes somewhat
to both Kepler and Galileo.
Now Newton knew Kepler's laws of planetary motion, and he had
(apparently) already worked out the 3 laws of motion. Your claim
is that given these, he can derive the force law. Certainly one
can make a good case for that, given lots of hindsight, and
a chalkboard. But Newton's results give a lot more than Kepler's
laws ... and Newton only used Kepler's laws as a means to validate
his own result.
Newton then goes on to use the three laws of motion, and the gravitational
force law to derive many things: non-Keplerian orbits, tides, the shape
of the earth, etc.
He, and subsequent generations of natural philosophers and astronomers,
used these results to predict what would be found, and what would happen.
Halley's comet is an example of such a prediction.
This is why people say that there is a Newtonian theory of gravitation:
because it has predictive power. It says nothing about the _cause_ of
gravitation. That takes a deeper theory.
> Lets look at another example, the Electromagnetic Theory. Does
> Coulomb's Law represent a new theory. No, it is just an empirical
> finding for yet another form of force. After all, there is no place
> in Newtonian mechanics that says "Thou shalt have no other forces".
> In fact the whole issue of what forces there can exist was left by
> Newton wide open, to be found later. So where does the EM theory
> start. To my mind, with Maxwell's Equations (though that was the
> culmination point only, Faraday deserves lots of the credit too).
> There these quantities, electric and magnetic fields, took a life of
> their own and became actual physical quantities, having independent
> existance and propagating through space, not just the "something you
> plug the charge into to obtain force".
>
Coulomb's result gives an electrostatic theory ... even combined with
the (approximate) magnetic force law, it doesn't give very much. Especially
since it doesn't tell you anything about currents. There is a lot to be
done between the 1770's and the 1830's, by which time all of the relevent
laws had been discovered. And there were many attempts to put together
an explanatory theory from these pieces ... Ampere, Gauss and Weber, Neumann,
and others. Yes, and Faraday presented his theory as well, though he
was unable to put it into mathematical form.
This leads us to Maxwell, who managed to put it all together, and get some
stunning new results from it.
Still, many people resisted Maxwell's results, because they were obviously
incompatible with Newton's three laws of motion. Among other things, there
was the velocity dependence in the forces.
> Now, I've seen claims that my concept of "theory" doesn't quite agree
> with the standard concept. Sure, it is but my opinion. There really
> is no standard definition of "theory" in science and I don't think
> there is even a need for a standard definition. So, I repeat, what I
> do is to express my opinions and they should be taken as such. You may
> recall that I wrote not long ago that "when scientist is talking about
> science, what he says is not an autoritative statement, just an opinion".
> I trust nobody thinks that I hold myself exempt from this rule.
>
> Mati Meron | "When you argue with a fool,
> meron@cars.uchicago.edu | chances are he is doing just the same"
>
I take a very simple approach: a law is something based upon experimental results.
A theory is based upon an abstraction of the laws, so that it is much more
mathematical in structure. But the theory must be able to give us back more than
the laws that were its inputs: the theory must have further predictive powers.
Best Regards, Peter
Subject: Re: Creation VS Evolution
From: Judson McClendon
Date: Sat, 30 Nov 1996 12:35:07 -0600
Phil Hetherington wrote:
>
> In article <329609F2.40DE@ix.netcom.com>, Judson McClendon
> wrote:
> >
> > Phil Hetherington wrote:
> > >
> > > I think that it would do a lot of people a lot of good if they would
> > just
> > > read something like that excellent publication "Scientific American" for
> > > twelve months or a couple of years -- some might need to read it for
> > longer!
> > [snip]
> >
> > I read Scientific American from the time I was 10 until I was 30. I was
> > completely convinced that evolution was true, and argued such many
> > times. I had to be drug, kicking and screaming, away from that position
> > by the evidence. Why don't you read the Bible for 20 years, and I'll
> > have more respect for your position.
> >
> I happen to be a retired elder in the United Reformed Church, my son is a
> minister in that Church, and I think know my Bible rather well having read
> it for something like seventy two years . In my late teens and since I have
> read widely in theology. I am 78 as indicated in my signature and when I
> retired eighteen years ago took the trouble to do a second degree with
> strong geological bias. The field work I did in the United Kingdom was
> completely convincing as to the accuracy of the geological evidence and
> geological time scale. As I have said in the Old World there doesn't seem
> to be the anti-science bias that shows up on these groups from the U.S and
> all main stream churches accept evolution as a mechanism used by God. The
> only ones who don't are minority imports from the States. My worry for a
> lifetime has been that those who fall into such anti science groups are
> sooner or later going to realise that they are building on sand. I want
> people to accept that they can accept scientific methodology and still keep
> faith in a God.
Since your response is to my message, I assume you take it that I am
anti-science. This is hardly the case. My personal belief is that
Genesis 1:28 ("And God blessed them, and God said unto them, Be
fruitful, and multiply, and replenish the earth, and subdue it: and have
dominion over the fish of the sea, and over the fowl of the air, and
over every living thing that moveth upon the earth.") encompases, among
other things, a mandate for science. But when the mind and heart of man
decides to 'explain away' the Creator, that is not science. It is what
is described in Romans 1:18:32
18 For the wrath of God is revealed from heaven against all ungodliness
and unrighteousness of men, who suppress the truth in unrighteousness,
19 because what may be known of God is manifest in them, for God has
shown it to them.
20 For since the creation of the world His invisible attributes are
clearly seen, being understood by the things that are made, even His
eternal power and Godhead, so that they are without excuse,
21 because, although they knew God, they did not glorify Him as God,
nor
were thankful, but became futile in their thoughts, and their foolish
hearts were darkened.
22 Professing to be wise, they became fools,
23 and changed the glory of the incorruptible God into an image made
like
corruptible man-- and birds and four-footed animals and creeping
things.
24 Therefore God also gave them up to uncleanness, in the lusts of
their
hearts, to dishonor their bodies among themselves,
25 who exchanged the truth of God for the lie, and worshiped and served
the creature rather than the Creator, who is blessed forever. Amen.
26 For this reason God gave them up to vile passions. For even their
women exchanged the natural use for what is against nature.
27 Likewise also the men, leaving the natural use of the woman, burned
in
their lust for one another, men with men committing what is shameful,
and
receiving in themselves the penalty of their error which was due.
28 And even as they did not like to retain God in their knowledge, God
gave them over to a debased mind, to do those things which are not
fitting;
29 being filled with all unrighteousness, sexual immorality,
wickedness,
covetousness, maliciousness; full of envy, murder, strife, deceit,
evil-mindedness; they are whisperers,
30 backbiters, haters of God, violent, proud, boasters, inventors of
evil
things, disobedient to parents,
31 undiscerning, untrustworthy, unloving, unforgiving, unmerciful;
32 who, knowing the righteous judgment of God, that those who practice
such things are worthy of death, not only do the same but also approve
of
those who practice them.
Is it strange, then, that we see these very signs about us in the world
today?
--
Judson McClendon judsonmc@ix.netcom.com
Sun Valley Systems http://www.netcom.com/~judsonmc/sunvalley.html
Subject: Re: No Newtonian Theory of Gravitation
From: meron@cars3.uchicago.edu
Date: Sat, 30 Nov 1996 19:48:53 GMT
In article <32A086FA.B78@mail.ic.net>, Peter Diehr writes:
>In article ,
>meron@cars3.uchicago.edu wrote:
>>
>> So, before it seems that I go to far off on a tangent, to me a new
>> theory begins at such a "branching point" where decisons are made and
>> new concepts and ideas introduced (or, possibly, previous concepts
>> acquiring a quite different meaning). With Newton, the Three Laws are
>> such a point (in physics, then you could separately point to calculus
>> in math), there is no doubt that there you witness the birth of a new
>> theory.
>>
>
>Agreed: this is a theory of mechanics. It gives you a method of determining
>future motion based upon the knowledge of current motion _and_ the
>type of interaction.
>
>That is, you need to know the force law.
Definitely.
>
>> OK, so how about gravitation. Once the laws of motion were there,
>> what else was needed. An assumption that the planetary orbits have
>> something to do with some force? Yes, but Newton was already
>> committed to the idea that any motion where the velocity changes (i.e.
>> specifically, any orbit) is the result of some force. An assumption
>> of universality? Yes, but Newton was already committed to
>> universality too, his laws were already stated as universal, not
>> something valid only in Southern England. So, there was no need for
>> new assumption or ideas, only taking the ideas that were already
>> embodied in the laws of motion and applying them to the existing set
>> of observations which were compiled in such an elegant form in
>> Keppler's Laws (I wonder whether Keppler ever realized what an
>> amazingly good job he did there). That's why I don't see Newtonian
>> Gravitation as an independent theory, only as an (natural) development
>> within Newtonian Mechanics.
>>
>
>Several points ... yes, Kepler did recognize how good a job he did!
>He was very excited about it, and even got a bit carried away. This
>isn't too surprising. But when he shared his results with Galileo,
>Galileo wasn't impressed. You see, Galileo was very prejediced in
>favor of the Copernican system, which retains a system of epicycles.
>It took a long time for people to fully break away from the idea
>that only circular motion existed in the heavens.
Yep, they inherited from the Greeks the belief that circular means
perfect and since everything in heavens is supposed to to be perfect,
all motion in heavens must be circular. Shows you that even Galileo,
who spent his life fighting against precoinceived notions, wasn't
immune to them.
>
>BTW, Kepler also worked on a force law ... and almost got it right.
>But I would have to dig around to find what he had proposed.
>
>Universality: yes, Newton's three laws of motion are supposed to
>be universal in scope ... but that is not where Newton applied the
>term: it is the Universal Law of Gravitation. Here the point was
>that that same locally observable force which we call gravity
>applies to all objects ... that is, it is not just earthly things
>that are attracted to the earth, but all things, in their proper
>measure. The proper measure is in their mass, and the reach of the
>force is universal.
Yeah, and there is no contradiction here. Once you assume that laws
of motion are universal, it is rather natural to assume that the same
is true for force laws.
>
>This was quite a break from Aristotelian ideas, and owes somewhat
>to both Kepler and Galileo.
>
>Now Newton knew Kepler's laws of planetary motion, and he had
>(apparently) already worked out the 3 laws of motion. Your claim
>is that given these, he can derive the force law. Certainly one
>can make a good case for that, given lots of hindsight, and
>a chalkboard. But Newton's results give a lot more than Kepler's
>laws ... and Newton only used Kepler's laws as a means to validate
>his own result.
Not quite. You seem to ignore the backwards - forward motion inherent
in the development of scientific ideas. You start with the simplest
case possible, use it in conjunction with the available empirical
data to point you in the direction of the "proper" relationship, then
once you got some relationship you check it for the more complex cases
to see whether it still makes sense.
So, your starting point in this case is "lets ignore that there are
many planets and see what happens for a single body acted upon by a
force. And lets take Kepler's laws as given". Starting with these
assumptions, the result is uniquely determined. And the "uniquely"
part is important, since it is not enough to find a relationship that
works if there are many such relationships. How do you choose?
From Newton's notes it seems that this is indeed the path he took.
Now, once he got that far, he could continue to the next step, i.e.
...
>
>Newton then goes on to use the three laws of motion, and the gravitational
>force law to derive many things: non-Keplerian orbits, tides, the shape
>of the earth, etc.
Exactly. Once you derive the force law for an idealized case, then
you proceed to apply it to real life cases, including multiple masses,
non point distributins etc. Same as after you find Coulomb's Law you
apply it to Non spherically symmetric charge distributions.
>
>He, and subsequent generations of natural philosophers and astronomers,
>used these results to predict what would be found, and what would happen.
>Halley's comet is an example of such a prediction.
Right.
>
>This is why people say that there is a Newtonian theory of gravitation:
>because it has predictive power. It says nothing about the _cause_ of
>gravitation. That takes a deeper theory.
The combination of Newton's laws with the harmonic oscillator force
law also has predictive power. I wouldn't call it an independent
theory, though.
>
>> Lets look at another example, the Electromagnetic Theory. Does
>> Coulomb's Law represent a new theory. No, it is just an empirical
>> finding for yet another form of force. After all, there is no place
>> in Newtonian mechanics that says "Thou shalt have no other forces".
>> In fact the whole issue of what forces there can exist was left by
>> Newton wide open, to be found later. So where does the EM theory
>> start. To my mind, with Maxwell's Equations (though that was the
>> culmination point only, Faraday deserves lots of the credit too).
>> There these quantities, electric and magnetic fields, took a life of
>> their own and became actual physical quantities, having independent
>> existance and propagating through space, not just the "something you
>> plug the charge into to obtain force".
>>
>
>Coulomb's result gives an electrostatic theory ... even combined with
>the (approximate) magnetic force law, it doesn't give very much.
Well, it gives exactly as much as Newton's law of gravitation does.
It provides a force law (idantical in form, by the way) and, in
conjuction with Newton's laws, enables you to generate predictions.
You just say "it doesn't give much" since you're aware that there was
morte to be found.
> Especially
>since it doesn't tell you anything about currents. There is a lot to be
>done between the 1770's and the 1830's, by which time all of the relevent
>laws had been discovered. And there were many attempts to put together
>an explanatory theory from these pieces ... Ampere, Gauss and Weber, Neumann,
>and others. Yes, and Faraday presented his theory as well, though he
>was unable to put it into mathematical form.
>
>This leads us to Maxwell, who managed to put it all together, and get some
>stunning new results from it.
Yep, that's where the real fun began.
>
>Still, many people resisted Maxwell's results, because they were obviously
>incompatible with Newton's three laws of motion. Among other things, there
>was the velocity dependence in the forces.
Well, as we know by now, these "oddities" were telling us something
very deep.
... snip ...
>
>I take a very simple approach: a law is something based upon experimental
>results. A theory is based upon an abstraction of the laws, so that it is
>much more mathematical in structure. But the theory must be able to give us
>back more than the laws that were its inputs: the theory must have further
>predictive powers.
That's sensible. But a law also has predictive powers as soon as
you're willing to use it universally, not only for the specific
experimental cases for which it was established.
Mati Meron | "When you argue with a fool,
meron@cars.uchicago.edu | chances are he is doing just the same"
Subject: Re: Creationism VS Evolution
From: Marty Zinck
Date: Sat, 30 Nov 1996 14:44:32 -0500
Literalists take the creation account literally, but we have to ask
which account they are talking about. They condemn the Pope for
accepting evolution and thus rejecting what the Bible says about it. His
Holiness may not need my support, but my Catholic friends will be happy
to see me on the Pontiff�s side for a change.
In Genesis 1, humans are created on the last day of creation and male
and female are created at the same time. In Genesis 2, which is the
older account, man is created early in the week before the animals and
woman does not appear until the end of the week as an after-thought. You
can�t have it both ways if you take it literally.
Literalists will have to believe that according to Genesis, the earth is
flat. But astronauts have brought us back pictures not of a flat earth
in the midst of waters, but of a beautiful blue and white globe swimming
in space.
Genesis says there is a skydome over the earth holding up the waters
that are above, and that are underneath the earth there are also
waters. In the flood story in Genesis 7, the skydome opened and the
waters pour down while the waters under the earth surge upward. The
covered the mountains to the depth of 18 cubits. To cover Mt. Everest,
the waters would have to be five miles deep. And where did these waters
go when the flood finally abated. The amount of water upon the earth is
a constant value, whether it is as water, ice, or atmosphere.
Joshua is said to have made the sun stand still so he could kill more
Amorites, which is a _very_ moral reason. But it is the earth that
moves around the sun and if he was able to get the earth to stop turning
on its axis, the force of gravity would have hurled everthing on the
earth, that was not nailed down, flying out into space. The sun does
not rise and set, no matter what the Bible says.
The Literalists problem does not end with the Old Testament. Read the
resurrection stories of Jesus at the end of the four Gospel to find out
who was in the empty tomb --one or two men, one or two angels? And who
got there first? and who saw the Christ first? and was it in Jerusalem
or Galilee?
It is said that Jesus ascended into heaven. But if He did ascend through
the skydome at the speed of Light, 186,000 miles per second, He would
not yet be at the edge of our galaxy.
If these questions disturb you, don�t take my word for it, just read the
first two chapters of Genesis and then make two lists of the order of
creation. Then go on to the Gospels and do the same with the birth
stories and the resurrection accounts. Put them side by side and see the
contradictions.
Thinking people have no trouble with these problems, but if you still
do, I suggest you get Bishop John Spong�s book, Rescuing the Bible from
the Fundamentalists, and work your way through it. And when you�ve done
that, I�ll suggest a tougher one.
In his final book, The Merry Heart, the late Robertson Davies writes,
�The Bible, which has now sunk to the level of a book of admonition and
law in the hands of the people who profess to take it literally, remains
perhaps the greatest compendium of history, philosophy, and faithful
reflection available to us.�
I agree. The Bible has influenced my life more than any other book and
it continues to do so. Its good influence over me increased greatly
after I stopped taking it literally.
It is not the liberals, but the literalists, who cause the Bible to be
neglected by so many people in our day. The Fundamentalists _are_ the
Anti-Christ they fear!
